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Canadian Yew

Taxus brevifolia Nutt.

Comments

provided by eFloras
The name Taxus baccata Hooker has been misapplied to this species.

The leaves of Taxus brevifolia are usually somewhat falcate.

The wood of Taxus brevifolia is hard and durable, yet easily worked, making it popular for construction of novelty items by local woodworkers. Because of this, large trees are unscrupulously poached; in some areas the species has been nearly extirpated. The bark of the tree is a promising natural source of taxol, a drug for treating various cancers; exploitation of the species for medicinal purposes is further threatening it.

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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
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Flora of North America Vol. 2 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
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Description

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Shrubs or small trees to 15(--25) m, dioecious; trunk to 6(--12) dm diam., straight to contorted, fluted; crown open-conical. Bark scaly, outer scales purplish to purplish brown, inner ones reddish to reddish purple. Branches horizontal to drooping. Leaves 1--2.9 cm ´ 1--3 mm, pale green abaxially, cuticular papillae present along stomatal bands, shiny yellow-green adaxially, epidermal cells as viewed in cross section of leaf mostly taller than wide. Seed ovoid, 2--4-angled, 5--6.5 mm.
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cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 2 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
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Distribution

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Alta., B.C.; Alaska, Calif., Idaho, Mont., Oreg., Wash.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 2 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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Habitat

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Seeds maturing late summer--fall. Open to dense forests, along streams, moist flats, slopes, deep ravines, and coves; 0--2200m.
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copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 2 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
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Synonym

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Taxus baccata Linnaeus subsp. brevifolia (Nuttall) Pilger; T. baccata var. brevifolia (Nuttall) Koehne; T. baccata var. canadensis Bentham; T. bourcieri Carrière; T. lindleyana A. Murray bis
license
cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 2 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
original
visit source
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eFloras

Common Names

provided by Fire Effects Information System Plants
Pacific yew
western yew
yew brush
yew
mountain mahogany
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Cover Value

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More info for the term: cover

Pacific yew commonly forms a dense subcanopy which provides excellent
hiding and thermal cover for large ungulates and other wildlife species
[34,68]. On riparian sites, it provides shade which maintains cool
water temperatures for salmonids and other anadromous fish [68].
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cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Description

provided by Fire Effects Information System Plants
More info for the terms: aril, dioecious, fruit, seed, shrub, tree

Pacific yew is a slow-growing evergreen shrub or tree which commonly
reaches 20 to 40 feet (6-12 m) at maturity [65,68]. On favorable
coastal lowland sites, scattered individuals can grow to 60 feet (18 m)
in height and have diameters of 2 to 3 feet or more (0l6-0.9 m) [5]. On
poor sites, such as those at higher elevations, Pacific yew grows as a
large sprawling shrub [62]. This large shrub or tree can reach maturity
at 250 to 350 years of age [62] and often survives for several centuries
[5].

Pacific yew is characterized by a conical crown and slender, drooping
horizontal branchlets [32,55]. The trunk is limby and often contorted
or malformed [29,32,62]. Twigs are slender, hairless and green, but
become dark reddish brown in the second growing season [32]. Bark is
very thin (approximately 0.25 inch [64 mm]), scaly, with purplish outer
scales covering newly formed reddish or purplish inner bark [30,32,62].
The root system is fibrous [68].

The sharp-pointed leaves are linear to lanceolate, 0.5 to 1 inch (1-3
cm) long, and spirally arranged [32,55,62]. Leaves are dark
yellow-green above and paler beneath [30,55]. Leaves persist for at
least 5 to 6 years [30,62].

Pacific yew is dioecious [30]. Globose, yellowish staminate cones
approximately 0.12 inch (3mm) in length are produced in abundance on
male plants [11,30]. Single, greenish, ovulate cones are borne on the
lower sides of branches [30,62]. Fruit is a red, fleshy, ovoid,
berrylike aril [30,55]. Each fruit is approximately 0.4 inch (1 cm) in
length and matures in one season [62]. The cup-shaped fruit surrounds a
large single, naked seed [30,70]. The seed is reddish, obvoid-oblong,
with a hard bony shell exposed at the apex [29,62].
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cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Distribution

provided by Fire Effects Information System Plants
Pacific yew grows along the Pacific Coast of southeastern Alaska
southward through western British Columbia to central California
[46,55]. In the Rocky Mountain region, it occurs from southeastern
British Columbia through northwestern Montana and northern Idaho into
eastern Washington and Oregon [46].

Dense stands of shrubby Pacific yew dominate approximately 40,000 acres
(16,000 ha) in the South Fork of the Clearwater Drainage of
north-central Idaho [14]. This plant has been essentially eliminated
from another 9,880 acres (4,000 ha) by timber harvest [14].
license
cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Fire Ecology

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More info for the terms: association, fire interval, fire regime, seed

Pacific yew is susceptible to heat damage and is most often associated
with forests characterized by long fire-free intervals. Fire is rare in
many old-growth forests of the Pacific Northwest [68]. Fire intervals
in forests containing Pacific yew have been estimated as follows:

Location Fire interval Reference

Bitterroot Mtns. ID, MT 60 years [50]
c Western Cascades, OR 100 years [52]
Siskiyous, OR 20 years [7]
nw CA - low elev. 500-600 years [68]
nw CA - mid elev. 150-200 years [68]

Mature moist-site stands in which Pacific yew grows as scattered
individuals are often considered relics from past fires [34]. In parts
of the Northwest, stand age ranges from 80 to 250 years where fire
intervals average 70 to 120 years [14]. Similarly, in parts of western
Montana, the age of Pacific yew averages approximately 210 years where
fire replacement cycles are estimated at 150 years [14]. This suggests
that the association of Pacific yew with moist microsites conveys some
protection from fire.

After fire, Pacific yew slowly reestablishes by means of bird-dispersed
seed as the overstory canopy develops.

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".
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cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Fire Management Considerations

provided by Fire Effects Information System Plants
More info for the terms: duff, prescribed fire, underburn

Fire history: Because of its sensitivity to fire, the age of Pacific
yew can be used to estimate minimum stand age [49]. However, because it
establishes after initial colonization, the oldest stem is often
significantly younger than the age of the stand itself [49].

Prescribed fire: Johnson and Simon [34] recommend against prescribed
fire in Pacific yew types. Although a light underburn will not damage
the duff layer, yew may be adversely affected. Scher and Jimerson [68]
note that "although prescribed burning reduces the probability of
catastrophic wildfires, precautions must be exercised to maintain
biodiversity by protecting temperature-sensitive species" such as
Pacific yew. In some areas, prescribed and/or wildfires can contribute
to the depletion of yew populations [68]. Broadcast burning after
clearcutting has virtually eliminated yew in some areas [61,68].
license
cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Growth Form (according to Raunkiær Life-form classification)

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More info on this topic.

More info for the term: phanerophyte

Phanerophyte
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat characteristics

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More info for the terms: shrubs, tree, vine

Pacific yew grows in a variety of cool and moist shaded habitats in
coastal lowlands and mountains [5,30,32]. It occurs in canyon bottoms,
on moist forested flats near streams, and scattered at various upland
sites [14,30,32]. At middle elevations in northern Idaho, it forms a
dense tangle of shrubs approximately 10 to 15 feet (3-5 m) in height.
Elsewhere, small groups or scattered individuals are more common [5,11].
Pacific yew grows on dry, rocky sites and in avalanche chutes west of
the Cascades [5]. However, it is commonly found in warm, humid
concavities [82]. Pacific yew is the most shade tolerant tree in the
Pacific Northwest [62]. In less humid climates, it may actually require
shade [41].

Plant communities: Pacific yew commonly grows beneath the dense shade
of western hemlock, Douglas-fir, and Pacific silver fir (Abies amabilis)
forests [5,68]. Although most often associated with relatively moist
plant associations dominated by western hemlock, Sitka spruce (Picea
sitchensis), and Pacific silver fir, it also occurs in relatively moist
microsites beneath species more typically associated with drier sites
such as ponderosa pine (Pinus ponderosa), incense cedar (Calocedrus
decurrens), Oregon white oak (Quercus garryana), Jeffrey pine (Pinus
jeffreyi), and knobcone pine (P. attenuata) [11,55,68]. In parts of
eastern Oregon and California, Pacific yew is a prominent component of
white fir forests [11,54]. In northern California and southwestern
Oregon, it is common in mixed evergreen forests dominated by white fir,
Douglas-fir, canyon live oak (Quercus chrysolepis), chinkapin
(Chrysolepis chrysophylla), and Pacific madrone (Arbutus menziesii)
[6,7,55,82]. At the extreme southern edge of its range, Pacific yew
grows beneath sequoia (Sequoia sempervirens) [11,27]. In the northern
Rockies, it is associated with grand fir and western redcedar forests
[11,56]. Pacific yew also occasionally grows in warmer subalpine fir
(Abies lasiocarpa)-Engelmann spruce communities [11].

Plant associates: Common plant associates in coniferous forests of the
northern Rocky Mountains include pachistima (Pachistima myrsinites),
northern twinflower (Linnaea borealis), menziesia (Menziesia
ferruginea), Rocky Mountain maple (Acer glabrum), blue huckleberry
(Vaccinium membranaceum), wild ginger, queencup beadlily, one-sided
wintergreen (Pyrola secunda), western rattlesnake plantain (Goodyera
oblongifolia), oneleaf foamflower (Tiarella unifoliata), and bunchberry
(Cornus canadensis) [6,13,25,81]. In southwestern Oregon and
California, vine maple (Acer circinatum), dwarf Oregon grape (Mahonia
nervosa), northern twinflower, salal (Gaultheria shallon), and hazel
(Corylus cornuta) grow with Pacific yew [6,67,82]. Elsewhere in the
Northwest, Pacific rhododendron (Rhododendron macrophyllum), vine maple,
salal, western swordfern (Polystichum munitum), Oregon oxalis (Oxalis
oregana), Pacific dogwood (Cornus nuttallii), and oceanspray (Holodiscus
discolor) are common associates [11].

Climate: Pacific yew grows in cool temperate and mesothermal climates
[40,41]. Abundance increases with increasing precipitation and
decreases with greater elevation and latitude [40]. Average annual
precipitation ranges from 18 to 116 inches (47-294 cm) [11]. Sites are
generally characterized by mild wet winters and warm dry summers [14].
Pacific yew is moderately tolerant of frost, but the protection offered
by a layer of snow is necessary in continental climates [41]. This
plant is resistant to flooding and survives temporary inundation [41].

Soils: Western yew commonly grows on deep, moist, well-drained soils
[62,77] and is well adapted to acidic conditions [41]. In British
Columbia, it tends to be most productive in alluvial habitats where
soils are nutrient-rich [41]. A study conducted in the Bitterroot
Mountains of Montana and Idaho indicated that sites dominated by Pacific
yew have high levels of nitrogen [51]. Pacific yew grows on soils
derived from a variety of parent materials including granite, diorite,
gabbro, serpentine, pre-Cambrian metasediments, schists, and gneiss
[14,42,67,79].

Elevation: Pacific yew grows at elevations ranging from 2,000 to 8,000
feet (610-2,438 m) [62]. In Oregon, it occurs at low to middle
elevations [74], and in British Columbia, it occurs from submontane to
subalpine habitats [41]. Elevational ranges by geographic location have
been reported as follows:
Reference
from 3,200 to 7,000 feet (975-2,134 m) in MT [17]
350 to 4,350 feet (104-1,329 m) in CA [11]
< 7,000 feet (2,134 m) in CA [55]
200 to 4,450 feet (60-1,350 m) in OR & WA [11]
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Cover Types

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More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

206 Engelmann spruce - subalpine fir
207 Red fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
FRES25 Larch
FRES27 Redwood
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Plant Associations

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More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K005 Mixed conifer forest
K006 Redwood forest
K007 Red fir forest
K012 Douglas-fir forest
K013 Cedar - hemlock - pine forest
K014 Grand fir - Douglas-fir forest
K015 Western spruce - fir forest
K029 California mixed evergreen forest
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cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Immediate Effect of Fire

provided by Fire Effects Information System Plants
Pacific yew has thin bark and is sensitive to heat damage [14,68].
Plants are generally killed by even light ground fires [49], and this
species is almost always eliminated from burned stands [14,50]. In
western Montana, Stickney [73] observed that all plants were eliminated
from burned stands. An abundance of Pacific yew can be equated with an
absence of fire [14].

Plants which occasionally survive fire do so because they occur in the
wettest concavities which are relatively unaffected by fire [7].
license
cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Importance to Livestock and Wildlife

provided by Fire Effects Information System Plants
More info for the terms: cover, fruit

Pacific yew provides important food and cover for many wildlife species
[34,68]. Old-growth grand fir/Pacific yew forests are often considered
critical moose winter habitat [61].

Browse: Many wild ungulates feed on Pacific yew including deer, elk,
and moose [14,21,49]. In parts of northern Idaho, it is a preferred
winter moose browse [14]. Although Pacific yew browse may be eaten
during all seasons, use is particularly heavy in fall, winter, and
spring [14,60,61]. In winter, moose eat available forage and bark which
they strip from trees [14]. Plants may be severely hedged in some areas
[60]. Use is typically greatest when other forage is buried by snow
[60]. Moose utilization by season has been documented as follows [60]:

percent aggregate use

May - July 3
July- September 0
October - November 42
December - April 41

In a winter study at a Connecticut nursery, as much as 77.1 percent of
all Pacific yew shoots were browsed by white-tailed deer [12]. Rabbits
and other small herbivores may also browse Pacific yew in many areas
[21].

Pacific yew is reportedly toxic to domestic livestock [65,77], but
conclusive evidence of toxicity is lacking [15,37]. The closely related
English yew (Taxus baccata) is poisonous to cattle, horses, sheep,
rabbits, and man [66]. Some researchers report that Pacific yew is
similarly toxic, particularly when cut, piled, and allowed to rot [32].
However, in many areas livestock appear to browse branches "with
impunity" [70]. Livestock use is generally limited to the winter months
or periods of food scarcity [15].

Fruit: Fruit of Pacific yew is sweet but reportedly poisonous to some
species [70]. It is readily eaten by many species of songbirds
including the Townsend's solitaire, varied thrush, and hermit thrush
[34]. The ring-tailed cat also feeds on the fruit of Pacific yew [77].

Foraging sites: Pacific yew snags may be used by foraging woodpeckers
[48].
license
cc-publicdomain
bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Key Plant Community Associations

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More info for the terms: association, climax, codominant, forest, habitat type, vine

Pacific yew grows as an understory dominant or codominant in a number of
coniferous forests of the Pacific Northwest and northern Rocky
Mountains. Overstory dominants include grand fir (Abies grandis), white
fir (Abies concolor), and western hemlock (Tsuga heterophylla). Vine
maple (Acer circinatum), queencup beadlily (Clintonia uniflora), and
wild ginger (Asarum caudatum) are common codominants. In parts of
northern Idaho, Pacific yew grows as a climax dominant which forms a
nearly contiguous shrublike overstory. It is listed as an indicator or
dominant in the following habitat type (hts), community type (cts), and
plant association (pas) classification schemes:

Area Classification Authority

CA mixed evergreen cts Sawyer and others 1977
CA, OR: Siskiyou Mtn. forest pas Atzet and Wheeler 1984
Province
CA, OR: e Siskiyous forest cts Waring 1969
n ID forest cts, hts Cooper and others 1987
OR: Abott Creek RNA forest cts Mitchell and Moir 1976
s OR: Cascade Mtns. forest pas Atzet and McCrimmon 1990
OR, ID: Wallowa- general veg. pas Johnson and Simon 1987
Whitman NF
n Rocky Mountains Pacific yew cts Crawford and Johnson 1985
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Life Form

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More info for the terms: shrub, tree

Tree, Shrub
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Management considerations

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More info for the terms: cover, litter, natural, selection, tree

Timber harvest: Pacific yew is uncommon on most recently harvested
sites [81]. It is sensitive to drastic changes in light and temperature
and can be severely harmed by increasing exposure to heat after tree
canopy removal [34]. Sensitivity to frost may also cause decreases in
yew after overstory removal [11]. Plants commonly turn orange or brown,
and the foliage dies back after clearcutting [5,11,49]. However,
Pacific yew often adapts to unshaded conditions through changes in twig
distribution and leaf morphology [11]. In a northern Idaho study,
approximately 78 percent of individual plants survived overstory removal
[11].

Reductions in the cover of Pacific yew are often dramatic. Antos [2]
reported 1.4 percent cover after grand fir types were clearcut in
western Montana. Prior to timber harvest, Pacific yew represented
nearly 20 percent cover. The effects of timber harvest have been
examined in a number of studies [4,18,19]. Uneven-aged individual tree
removal or group selection is much less damaging to yew than
clearcutting [34]. Broadcast burning also greatly reduces the cover of
Pacific yew [61].

Wildlife: In parts of northern Idaho, moose browse Pacific yew heavily
during winter. Browse in clearcuts is generally covered by deep snow
and inaccessible to moose. However, plants within the understory of
old-growth forests are readily accessible and heavily utilized [60].
Clearcutting in these areas does not favor moose. For best moose
habitat, timber harvest should be avoided in old-growth grand
fir/Pacific yew communities [61]. To protect Pacific yew and maintain
adequate moose browse, whole tree removal should be used where possible
to lessen the need for slash disposal [61]. Slash should be piled and
then burned rather than broadcast burned. Natural grand fir and
Engelmann spruce (Picea engelmannii) regeneration can be supplemented by
planting Douglas-fir (Pseudotsuga menziesii) in small clearings [61].

Damage: Pacific yew may be severely damaged by rabbits and deer [21].
Moose occasionally kill trees by girdling the trunk [14]. In some
locations ungulates can hedge or even remove Pacific yew from springs
and seeps [14]. In parts of northern Idaho, heavy moose browsing can
prevent Pacific yew dominance on ridges and south aspects [14]. In some
areas, yew regeneration can be significantly impacted by moose [14].

Pacific yew is resistant to damage from sulfur dioxide pollution [11]
and is resistant to insects and disease [50].

Allelopathy: Seedlings of other species are rarely found beneath yews
[49]. Pacific yew has exhibited inhibition both in laboratory
experiments and in the field [16,64]. Allelopathic compounds may be
concentrated in senescent leaves and leached into the litter [64].

Bark collection: Approximately 20,000 pounds (9,080 kg) of bark is
required to produce 2.2 pounds (1 kg) of taxol [1]. In some locations,
populations of Pacific yew are threatened by collectors gathering bark
for its anticancer properties [68]. If this demand continues, this
important species could become scarce in many areas [11].

Old growth indicator: Scher and Jimerson [68] noted that long-lived
temperature-sensitive species such as Pacific yew may serve as useful
indicators of old-growth forests.
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Occurrence in North America

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AK CA ID MT OR WA BC
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bibliographic citation
Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Other uses and values

provided by Fire Effects Information System Plants
More info for the term: serpentine soils

Pacific yew is an attractive ornamental which is frequently used as a
hedge plant [65]. It was first cultivated in 1854 [65]. According to
Kruckeberg [42], only the best foliage forms of Pacific yew can compare
with the much more widely planted English yew. A shrubby form of
Pacific yew, often associated with serpentine soils, is generally
considered the most desirable ornamental form [42]. Once established in
the garden, Pacific yew grows well in partial shade or full sun [42].

Some Native American peoples traditionally associated Pacific yew with
death and bereavement [32,75]. The fragrant foliage was used as a
deodorant and cleaning agent [75]. Tonics made from Pacific yew were
used medicinally by many peoples of the Pacific Northwest [75].
Although seeds are poisonous, the fleshy portions surrounding them were
sometimes eaten [75]. The supple, stringy underbark was sometimes used
for braiding and weaving various items [32].

Taxol, a substance obtained from the bark of Pacific yew [33], has
inhibited the growth of various types of cancer cells in experimental
tests [1,44]. Clinical trials indicate that taxol produces a definite
but limited activity against metastatic melanoma and some types of
leukemia [44]. It may also be useful in treating ovarian cancer and in
inhibiting the growth of carcinosarcoma cells [11,44,38]. Taxol
inhibits the replication of Trypanosoma cruzi, a pathogenic protozoan
which causes Chagas disease [11], as well as the disease-causing
flagellate Trichomonas vaginalis [35].

Researchers are currently working on methods to synthesize taxol in the
laboratory, but efforts to date have been only partially successful
[39]. Pacific yew yields more taxol than any other species of yew
(Taxus spp.) and remains the primary source of this substance [11].
Recent experiments suggest that it may soon be possible to obtain taxol
from the leaves rather than from the bark [39].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Palatability

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Foliage of Pacific yew is at least somewhat palatable to many large
ungulates and is highly palatable to moose, particularly during the fall
and winter [14,60]. Fruit is highly palatable to many species of small
birds and mammals [5,77].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Phenology

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Fruit of Pacific yew matures in a single season. Seeds ripen in
September and October [30], and the fruit generally falls from the plant
in October [77]. Flowering and fruiting has been documented as follows:

Location Flowering Fruit ripens Reference

CA April-May ---- [55]
n ID ---- August-October [58]
WA June August-October [65]
Pacific Northwest April-June ---- [30]
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Plant Response to Fire

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Pacific yew reoccupies burned areas through bird-dispersed off-site
seed. Although vegetative regeneration is possible after mechanical
disturbance, Pacific yew's susceptibility to heat damage makes postfire
sprouting unlikely or impossible.

This plant may require shelter provided by other species for
reestablishment [50] and typically recovers slowly. Hofman [31]
observed that seedling germination was delayed for at least 6 years
after a hot slash burn in northern Idaho. Pacific yew is rare on
recently burned sites, even where it was a common component of preburn
communities [18,20,71]. In a northern Idaho study, Pacific yew was
present on 80 percent of the preburn plots but was absent from all plots
during the first years after fire [72,73]. In parts of the northern
Rocky Mountains, it is described as the "only principal residual species
eliminated by fire" [73].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Post-fire Regeneration

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Secondary colonizer - offsite seed
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regeneration Processes

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More info for the terms: forest, layering, natural, seed, series, stratification

Pacific yew can establish beneath a closed forest canopy by seed or by
vegetative means [49]. In many areas, layering is the primary mode of
reproduction, but seedlings are also common on some sites [2].

Seed: Most species of yew (Taxus spp.) produce at least some seed
annually [65]. Seeds can remain viable for 5 or 6 years if properly
stored [65]. Conclusive evidence is lacking, but some researchers have
suggested that seed may be stored in the soil [31]. Seed is commonly
dispersed by birds, and some long-distance transport is possible [50].
Passage through avian digestive tracts may affect seed dormancy [11].

Germination: Seeds of Pacific yew have a "strong but variable" dormancy
[65] and generally require stratification before germination can begin
[53]. In laboratory experiments, seeds germinated well after prolonged
warm and cold stratification [65]. Seed can be planted 0.4 to 0.5 inch
(10-13 mm) in depth and subjected to alternating day (86 degrees
Fahrenheit [30 deg C]) and night (68 degrees Fahrenheit [20 deg C])
temperatures for at least 28 days. However, even when properly treated,
some seed may not germinate until the second spring. Results of an
experimental test were as follows [65]:

stratification temp. duration germ. capacity
warm cold day night (days) (avg. %) (range)

--- --- 86 F 68 F 60 55 50-99

In other laboratory tests, average germination ranged from 50 to 60
percent [77]. Under natural conditions, germination may not take place
until the second year [65].

Seedling establishment: Seedling establishment is generally more
favorable beneath a canopy than in canopy gaps [14]. Means [52]
observed seedling densities of 0.4 per acre (1/ha) in gaps but noted 47
per acre (115/ha) beneath a canopy in the western Cascades of Oregon.
Seedlings are reportedly uncommon in undisturbed situations but are
often abundant in partially cut areas where yew is present [11].

Vegetative regeneration: Branches and stems of Pacific yew commonly
root when in contact with the soil [14,49]. Plants are generally
unharmed after being flattened by large conifers during canopy break-up
[14,49]. Crushed yews often form a series of layered branches that give
rise to numerous individual plants [14,49]. Regeneration of Pacific yew
is favored by falling debris [49]. Layering enables Pacific yew to
quickly expand into gaps created as senescent conifers fall. Sprouts
generally develop from cut or broken stumps [14]; epicormic branching is
also common [11].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regional Distribution in the Western United States

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
4 Sierra Mountains
8 Northern Rocky Mountains
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Successional Status

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More info for the terms: climax, competition, cover, fire-sensitive species, mesic, phase, tree

Pacific yew is present in many climax or near climax communities of the
Pacific Northwest and northern Rocky Mountains [9,51,59,81]. It is a
particularly common component of old-growth grand fir, western redcedar,
and Douglas-fir-western hemlock communities [23,49,51,68]. Pacific yew
increases in cover up to a stand age of at least 500 years in
northwestern old growth Douglas-fir forests which are characterized by
long fire-free intervals [68]. This fire-sensitive species is absent
from areas characterized by high fire frequencies.

Pacific yew does occur on disturbed sites, including previously logged
stands [11], but reaches greatest abundance in undisturbed areas
[19,68]. Plants often grow as suppressed individuals in undisturbed
stands [26]. After timber harvest, this residual species expands as the
overstory develops [5], but where residual plants have been removed,
such as by broadcast burning, plants do not generally develop until a
protective overstory canopy has formed [50].

Pacific yew was common in mature stands 230 years or older but was
absent in second-growth communities (50- to 80-year-old stands) in
Washington [57]. Similarly, it represented 15 to 20 percent cover in
various old-growth stands in the northern Rocky Mountains but was rare
(1.4 to 2 percent cover) in immature stands (7 to 16 years old and 30 to
90 years old) [2,3,4]. Percent cover of Pacific yew in different aged
stands in western hemlock-Douglas-fir forests of the western Cascades
was documented as follows [69]:

stand age
(years) 2 5 10 15 20 30 40 undist. old growth
% cover 0.05 0.18 0.16 1.51 0.66 2.26 0.49 9.56

Mesic old-growth forests in canyons of the Bitterroot Mountains in Idaho
and Montana are commonly dominated by Pacific yew, western redcedar,
and/or grand fir [49]. Pacific yew typically establishes after the
initial colonization period, and is described as the only "relay"
species not colonizing these sites in early seral stages [49]. The
ultimate composition of these forests (dominance by Pacific yew, grand
fir, or western redcedar) is largely attributable to random events which
occur during stand establishment rather than to a sequential replacement
process [49,50].

In parts of the northern Rocky Mountains, the short tree, Pacific yew,
"expresses climax sociological dominance over tall conifers" such as
grand fir [14]. This situation differs from the classical pattern in
which progressively taller taxa gradually assume dominance over shorter
forms [14]. The successional role of Pacific yew in these forests has
been subject to a number of interpretations. However, Pacific yew is
generally considered the climax dominant because, in the absence of
disturbance, it successfully replaces itself "to the near exclusion of
tall conifers" [14]. Evidence suggests that grand fir may be slowly
eliminated where Pacific yew is replacing itself successfully [14,34].
"At climax, other tree species occur primarily as a result of gap-phase
replacement in the yew canopy and definitely do not have as great an
influence on the community as [Pacific yew]" [14]. Gap phase
replacement or microsuccession prevents the development of an exclusive
canopy of Pacific yew because other conifer seedlings tend to outcompete
yew in the canopy openings. Elsewhere, grand fir and other conifer
seedlings may be eliminated by dense yew competition [68]. However, on
sites where Pacific yew occurs only sporadically, grand fir often
reproduces more successfully.
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Synonyms

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Taxus baccata var. brevifolia
Taxus baccata ssp. brevifolia
Taxus boursieri
Taxus lindleyana
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Taxonomy

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The currently accepted scientific name of Pacific yew is Taxus
brevifolia Nutt. [36]. Pacific yew is a member of the family Taxaceae
[29].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Value for rehabilitation of disturbed sites

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More info for the term: seed

Potential rehabilitation value of Pacific yew is unknown. However,
plants can be easily propagated from cuttings [5,42] or seed [65].
Cleaned seed averages approximately 17,600 per pound (39/g) [65].
Techniques for propagation from seed have been examined in detail
[21,28,65].

The fibrous root system of Pacific yew can aid in stabilizing stream
channels [68].
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Wood Products Value

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The nonresinous wood of Pacific yew is fine grained, heavy, hard, and
very strong [5,32,55,62]. It is elastic but very durable, and resists
decay [5,32]. The sapwood is light yellow and thin, and the heartwood
is bright orange or rose red [5]. The wood responds well to finishing
and turns well on lathes [5,30]. This attractive wood has been used to
make canoe paddles, tool handles, poles, and fence posts [32,62]. It is
sometimes used in carving, cabinet-making, and for turned articles
[5,65] but has little or no commercial importance [30,32].

Native Americans traditionally used Pacific yew for constructing
harpoons, spear handles, eating utensils, wedges, paddles, and clubs
used in battle and for hunting seals [5]. Pacific yew is renowned for
its value in making bows and was formerly referred to as "bow plant" by
the Salish people [75]. Bows made from Pacific yew tended to be broad,
short, and flat [80]. Pacific yew is still used to craft some of the
finest archery bows. The best bows are made from wood which has been
cured for several decades [5] and are, not surprisingly, quite costly.
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Tirmenstein, D. A. 1990. Taxus brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Associated Forest Cover

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Pacific yew commonly occurs as an understory species in several forest cover types. It is a major component in some stands, but in most it is minor to rare. In some types, it tends to be found mostly on microsites. Some examples: In stands of ponderosa pine (Pinus ponderosa), grand fir (Abies grandis), and western larch (Larix occidentalis) in the drier interior forests, yew is found in moist areas near streams and springs (but on well drained soil); on wet, hummocky sites west of the Cascades, yew can be found in Oregon white oak (Quercus garryana)-Oregon ash (Fraxinus latifolia) stands (ash occupies the low, wet spots and yew grows with the oak on slightly raised hummocks); scattered large yew trees grow along the Clackamas River in northwest Oregon on berms and banks between first and second bottomlands in stands of black cottonwood (Populus trichocarpa), red alder (Alnus rubra), hawthorn (Crataegus spp.), crab apple (Malus spp.), and willow (Salix spp.) (3,47). By far, Pacific yew is most common in dense conifer forests. Among the major Society of American Foresters (16) cover types in which Pacific yew is found are: Engelmann Spruce-Subalpine Fir (206), Interior Douglas-Fir (210), White Fir (211), Grand Fir (213), Black Cottonwood-Willow (222), Western Hemlock (224), Western Redcedar-Western Hemlock (227), Western Redcedar (228), Pacific Douglas-Fir (229), Douglas-Fir-Western Hemlock (230), Port-Orford-Cedar (231), Redwood (232), Oregon White Oak (233), Douglas-Fir-Tanoak-Pacific Madrone (234), Sierra Nevada Mixed Conifer (243), and Pacific Ponderosa Pine-Douglas-Fir (244) (4,8,11,17,24,25,35,45,47).

In western Oregon, Douglas-fir was present on 89 percent of the forest inventory plots in which yew was tallied. A list of plants found most frequently with Pacific yew on these plots (table 1) indicates the broad range of conditions to which the species can adapt.

Table 1- Plants frequently found on plots with Pacific yew present, western Oregon.
Species Percentage
of plots
Indicator value¹ Pseudotsuga menziesii 89 Common Berberis nervosa 75 Common Polystichum munitum 75 Mesic, common Acer circinatum 70 Common Tsuga heterophylla 59 Cool, common Gaultheria shallon 59 Warm, mesic to dry Corylus cornuta var. californica 43 Warm, dry Acer macrophyllum 39 Warm Vaccinium parvifolium 39 Warm, common Thuja plicata 36 Moist, common Alnus rubra 36 Warm, moist Rhododendron macrophyllum 34 Cool, mesic Cornus nuttallii 32 Warm, dry Holodiscus discolor 27 Hot, dry Linnaea borealis 27 Mesic Arbutus menziesii 25 Warm, dry Abies grandis 23 Warm, dry Xerophyllum tenax 23 Cool, dry Rhus diversiloba 20 Hot, dry Oxalis oregana 20 Warm, moist ¹Based on information from 4,24, and 45.
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Climate

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Pacific yew is found over a wide range of moisture and temperature conditions (8,11,19,35,40,44). In dry, subhumid areas with an average annual precipitation as low as 470 mm (19 in), it is confined to streamside areas and the lower third of north-facing slopes. Some large specimens can be found in such environments; for example, the largest known yew tree in Idaho- 84.8 cm (33.4 in) d.b.h. and 8.5 m (28 ft) tall- is at the bottom of Hell's Canyon in an area that receives about 500 mm (20 in) of precipitation annually (21). On the Queen Charlotte Islands, Pacific yew is confined to the borders of inlets (44). Throughout much of its range within humid and superhumid forests (precipitation of 1400 to 4000 mm [55 to 157 in]), it can be found on all slopes, benches, and ridgetops. For example, a large yew tree in Oxbow County Park near Troutdale, Oregon (precipitation about 1450 mm [57 in]), is on the highest point in the park, a 210-m (690-ft) ridge overlooking the Sandy River 168 m (550 ft) below (3). Pacific yew is found from sea level in coastal areas to 2440 m (8,000 ft) in the Sierra Nevada. Length of growing season ranges from 60 to 300 days, with annual minimum temperatures from -15° to -12° C (5° to 10° F) (4,8,11,24,25,35,45).

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Damaging Agents

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Pacific yew is sensitive to damage from fire, and, where the overstory has been removed, it is sometimes damaged by exposure to the sun, wind, and cold (10,11,26,35,44). It resists damage from sulfur dioxide and was the least sensitive of 12 coniferous species to smelter fumes at Trail, British Columbia (26). Diseases of Pacific yew seedlings have not been studied, but Rhizoctonia solani, Phytophthora cinnamoni, and Pythium sp.have caused damping-off and seedling root rot in yews in the East. No serious leaf diseases have been reported. Snow blights- Neopeckia coulteri and Herpotrichia juniperi- have caused localized damage, and four needle blights are caused by Macrophoma taxi, Mycosphaerella taxi, Phoma hystrella, and Sphaerulina taxi. A stem canker is caused by Diplodia taxi, and twig blights by P. hystrella and Physalopspora gregaria. Two root diseases- Armillaria ostoyae (obscura) and Phaeolus schweinitzii have been reported on Pacific yew in Idaho (26).

Although seasoned heartwood of Pacific yew is extremely durable, large living Pacific yew trees often have heartrot or hollow boles (11,23). Many of the yew trees over 50 cm (20 in) d.b.h. tallied on non-Federal land in California, Oregon, and Washington could not be bored to determine age because of rotten or hollow trunks (47). Heartrot fungi infecting Pacific yew include Phellinus nigrolimitatus, P. pini, P. robustus, and Fomitopsis rosea (26).

Several insects cause damage to yews in the eastern United States, including Lecanium fletcheri (called Fletcher scale or taxus lecanium), Pseudococcus comstocki (Comstock mealybug), Dysmicoccus wistariae, Pseudococcus maritimus (grape mealybug), and Maladera castanea (Asiatic garden beetle) (2). No damage to Pacific yew in forested settings has been confirmed. Reported damage to Pacific yew foliage by budworms (Choristoneura spp.) in areas of heavy budworm infestation is thought to be heat or frost damage resulting from the defoliation of the overstory (5,41).

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Flowering and Fruiting

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Pacific yew is dioecious. Male strobili are stalked, bud-like, pale yellow, and composed of 6 to 12 filamentous stamens, each with 5 to 9 anthers. They are abundant on the underside of branch sprays and usually appear in May or June. Female strobili are less abundant, greenish, and composed of several scales. They also are borne on the underside of branches. The fruit is an ovoid-oblong seed about 8 mm (0.3 in) long, partially enveloped by a fleshy, berrylike, scarlet, cup-shaped disk called an aril. Pollen is dispersed by wind in the spring (6,11,19,22).

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Genetics

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Pacific yew occurs in nature as a shrub or a tree, but whether the two forms are distinct subspecies, races, or varieties is not known. Three cultivars have been reported: cv erecta, a columnar form; cv nana, a dwarf form; and cv nutallii, a drooping form. A hybrid between Taxus brevifolia and T. cuspidata (Japanese yew) has been reported, but has no botanical standing. Pacific yew was originally classified as a variety of T. baccata (European yew), which it closely resembles; some botanists grouped all seven of the currently recognized species of Taxus worldwide as varieties of T. baccata. Where different species grow near each other, interspecific hybrids frequently occur, lending support to the view that there is but one species (13,22,23,34,44). Further evidence of the close similarity of the species of Taxus is provided by bark analyses which show that most species contain taxol (9), and by an analysis of heartwood constituents of T. baccata, T. brevifolia, T. cuspidata, and T. floridana: the four species were found to be "chemically almost indistinguishable" (15)

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Growth and Yield

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Pacific yew, unlike most woody plants that grow in heavily shaded forest understories, often has a straight bole. Although yew trees are reported to have typically fluted, ridged, and asymmetrical trunks, often with tightly spiraled grain (6,11,23,37,44), yew cutters in southwest Oregon reported that many yew trunks were round and unfluted above the base section, and straight-grained (7). Large limbs are common in the mid and upper bole. The crown tends to be ragged and lopsided. Pacific yew "reaches" for light by way of limbs that may be as long as the tree is tall. Young trees often have an umbrella-shaped crown of flat branches, and old trees have long drooping spray-like branches. Pacific yew is sometimes shrub-like, forming dense thickets. In western Montana, parts of Idaho, northeastern California, the Blue Mountains of eastern Oregon and southeastern Washington, and at high elevations throughout its range, the shrub form of yew often occurs in the absence of tree-size specimens (3,8,10,11,20,27,30,31,35,44,49,50). In other areas, large tree-size yews may occasionally be found in or near yew shrub thickets (3). Whether the differences in size and form are genetic traits or the results of environment and stand history is not known.

The needles of Pacific yew are dark green on the underside, two ranked, and spirally arranged on twigs. The bark is purplish, papery thin, and scalelike. New bark is rose red (6,19,22,40). The wood is fine grained, hard, and heavy: at 712 kg/m³ (about 44 lb/ft³) (8 percent moisture content), it is the heaviest of U.S. conifers, comparable in weight to high-density hardwoods such as ash, oak, and hard maple (46). Heartwood is red to brownish red, and sapwood is whitish yellow to bright yellow.

Pacific yew grows slowly, taking about the same time to grow to 30 cm (12 in) in d.b.h. as other conifers in the same stand take to grow to several times that size. Height growth is correspondingly slow. Trees larger than 50 cm (20 in) in d.b.h. and taller than 12 m (40 ft) are rare within most of the species' range: they account for less than 2 percent of the yew trees tallied on inventory plots on non-Federal land in California, Oregon, and Washington. The following tabulation shows average height by diameter class as determined from 55 Pacific yew trees randomly selected in Oregon and Washington (47):

D.b.h Total height 10 cm (4 in) 6 m (20 ft) 20 cm (8 in) 8 m (26 ft) 30 cm (12 in) 10 m (31 ft) 40 cm (16 in) 11 m (37 ft) 50 cm (20 in) 13 m (43 ft) 60 cm (24 in) 15 m (49 ft) Because of the slow growth of individual trees and because the species is typically found as an occasional tree in stands of other tree species, volumes and yields of Pacific yew are low. Stands with 125 yew trees/ha (50/acre) that are 20 cm (8 in) in d.b.h. and larger have been observed, but always in association with other species (3). The theoretical volume of yew wood in such stands could be as much as 140 m³/ha (2,000 ft³/acre), including the volume in main stems from ground level to tip. The greatest volume of Pacific yew found in randomly located plots on non-Federal land in California, Oregon, and Washington was 28 m³/ha (400 ft³/acre) (47). These are gross volume estimates. Because heart rot is prevalent in large yew trees, net volume would be considerably less.

In Idaho, analyses of increment cores and stem sections of yew trees from mature stands showed annual growth in diameter at 15 cm (6 in) above ground to range from 0.05 cm (0.02 in) to 0.25 cm (0.10 in). The following tabulation shows diameters by age class (1l):


Age in years Diameter at 15 cm (6 in)
above ground 25 2.5 cm (1.0 in) 50 5.0 cm (2.0 in) 75 11.4 cm (4.5 in) 100 15.2 cm (6.0 in) 125 22.9 cm (9.0 in) The largest known Pacific yew tree is found in a cool, moist valley in western Washington (28). Large yew trees are, however, more prevalent on somewhat drier sites with warm, moist winters. Forty-seven percent of all the yew trees larger than 30 cm (12 in) tallied on inventory plots on non-Federal land in California, Oregon, and Washington were in a 4-county area in southwestern Oregon at mid to low elevations in the drier interior valleys and slopes between the Cascade and Coast Ranges, and in the Klamath Mountains (47).

Although Pacific yew is sometimes damaged by heat, frost, and wind, especially after overstory trees have been removed (10 , 11,35,44), it can sometimes respond to release. On permanent plots in western Oregon measured 12 years apart, diameters of undamaged yew trees left after removal of overstory trees grew an average of 0.18 cm/yr (0-07 in/yr) and trees under dense overstories grew 0.06 cm (0.02 in) (47).

The adaptation of Pacific yew to overstory removal is made possible through morphological changes in the needles-length, cuticle thickness, and deflection from the horizontal-and development of epicormic twigs (10,11).

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Reaction to Competition

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Pacific yew is very tolerant of shade (1,11,44). It appears to require shade for establishment and can grow and develop under heavy forest canopies. On many sites, it is able to adapt to overstory removal (10,11), and large, old trees can be found that have been in the open much of their lives (3).

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Rooting Habit

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The root system of Pacific yew is deep and wide-spreading (22).

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Seed Production and Dissemination

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Fruits ripen from August to October of the same year that flowering occurs. Fruits either drop to the ground or are taken from trees by birds or rodents. Birds devour the fleshy arils and void the seeds which remain viable. Chipmunks and squirrels often take only the seeds. Rodents and some birds-nuthatches, for example-cache yew seeds, thus creating the clusters of yew seedlings observed in some areas (11). The seed is about 6 mm (0.24 in) long with a depressed hilum, bony inner coat, and membranous outer seedcoat. Pacific yew is a prolific seeder (19,43). Seeds average about 33,100/kg (15,000/1b) after cleaning (39). The frequency of good seed crops is unknown.

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Seedling Development

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Seeds of Pacific yew germinate slowly and require stratification. Germination tests indicate that 30° C (86° F) day and 20° C (68° F) night temperatures are desirable (11,19,43). Germination is epigeal, and usually in heavy organic matter. In a study in Idaho, wild yew seedlings were distributed in seedbeds as follows (1l):

Type of seedbed Percentage of seedlings Forest litter 61 Decaying wood 20 Bird and rodent caches 16 Mineral soil _3_ 100 Yew seeds sown in nursery beds in late spring require mulching. Beds require shading during the summer and again in December. Some seeds do not germinate until the second spring after sowing (39).

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Soils and Topography

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Pacific yew grows best on deep, moist or rich, rocky or gravelly soils. In dry interior forests, the species develops best along mountain streams, and in shady canyons, ravines, and coves. Within the moist maritime climate of the Pacific Northwest, it grows most abundantly in drier, warmer environments. A partial list of soils on which Pacific yew grows includes those in the orders Ultisols, Alfisols, and Inceptisols (4,11,20,24,25,27,30,37,45,50).

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Special Uses

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The wood of Pacific yew has been used for archery bows, canoe paddles, tool handles, gunstocks, boat decking, furniture, musical instruments, carved figurines, and miscellaneous novelty items. (In a recent western State gubernatorial election, campaign buttons were made of yew wood.) Japanese have used Pacific yew for ceremonial "Toko" poles, which they place next to entrances of their homes (6,19,23,29,44). Pacific yew's resistance to decay makes it useful for fenceposts. Of seven northwest species tested for use as untreated fenceposts, Pacific yew was the second most durable, with an average service life of 25 years (33). In the mid-1980's Japanese purchasers paid $3,600 per thousand board feet (Scribner scale) for Pacific yew logs, mostly for wood carvings. In 1989, Japanese buyers agreed to pay $4,150 per thousand for grade 1 yew logs, and a Taiwanese buyer paid $6,100 (7).

Among Native Americans, Saanich Tribal women used Pacific yew to remove underarm hair; Okanagans made a red paint from ground yew wood mixed with fish oil; several tribes smoked dried yew needles, which was said to cause dizziness; Haidas believed that women who ate yew berries would not conceive. Yew was valued as an item of trade and used in making instruments for hunting, fishing, and warring; tools, such as mauls and splitting wedges; household utensils, such as bowls and spoons; and medicine for a broad range of ailments (23,29,44).

Pacific yew is again being used for medicinal purposes. In the late 1960's, taxol-a complex compound extracted from yew bark-was identified as a possible anticancer agent (18,48). The National Cancer Institute (NCI) has found taxol to be one of the most promising of more than 120,000 plant compounds tested for anticancer properties. Taxol appears to be effective against a wide range of tumors, and good responses have been obtained in the treatment of refractory ovarian cancer (9,38).

In 1988, the NCI acquired 27 700 kg (60,000 lb) of dried Pacific yew bark, collected from trees cut down in southwestern Oregon. On average, one yew tree yielded 18 kg (40 lb) of green bark, which weighed about 9 kg (19 lb) dried (7). From the 27 700 kg of dried bark, about 4 kg (9 lb) of dry, crystalline taxol was extracted. Clinicians in several locations across the country have asked for increased supplies of taxol to expand tests to a broader range of cancer types. In January 1989, the NCI solicited another 27 700 kg of yew bark (9).

The 27 700 kg of yew bark already collected and the second 27 700 kg ordered represent 6,000 to 7,000 trees. Most of these trees were cut or will be cut on Federal forest land where yew has not been inventoried. On non-Federal lands in California, Oregon, and Washington, where inventories have been made, there are an estimated 700,000 Pacific yew trees 28 cm (11 in) d.b.h. and larger, the size of most trees cut for bark collection. Almost all the yew trees on non-Federal land are survivors of logging operations that removed the old-growth overstory (47). On Federal land where old-growth forests still exist, many more yew trees are thought to be present, but trees of the size needed to produce large quantities of bark are not abundant in most areas. An unknown but unquestionably significant percentage of the original yew resource has already been destroyed in logging. In the process of harvesting Douglas-fir and other timber species, mostly by clearcutting, yew trees were either cut or knocked over and broken up by machinery. Yew trees were seldom taken in primary logging operations, but some yew wood was later salvaged by firewood cutters and gleaners gathering wood for specialty products. Most of the yew trees that existed in logged areas were burned in slash-disposal fires. In many logged areas, the rootstocks have survived and resprouted, so, although the wood and bark of many yew trees were destroyed, there seems to have been little threat to the existence of the yew germ plasm.

Continued or increased demand for yew bark for taxol production could further decrease a resource that has already been greatly reduced. Attempts to synthesize taxol in the laboratory have failed, and prospects for success in the future are considered to be poor. The only known source of taxol now is yew bark. Taxol has been found in most of the several other species of Taxus that exist, but Pacific yew is the only one that is considered to be a practical source of quantities sufficient for clinical use (9,12). At least one private organization has begun to investigate alternative ways of producing taxol, through tissue culture and by growing vegetatively propagated seedlings in a controlled environment (7).

The several species of yew in both the western and eastern hemispheres are thought to have poisonous seeds and foliage. Incidents of livestock poisoning by yew have been reported in Europe and North America. Conversely, in both Europe and North America, domestic and wild animals are known to browse yew foliage without ill effects. If and under what conditions yew foliage is poisonous are not known (13,14,22,32). Pacific yew is browsed by moose in the South Fork of the Clearwater River basin in Idaho, where the tree is considered critical to the animals' survival (36). Pacific yew is also browsed heavily by elk and occasionally by deer in Oregon and Washington (20,23,30).

Sprouts and epicormic branches that form in response to stand disturbance are favored by browsing animals. Repeatedly browsed yews in clearcut areas sometimes develop compact bushy crowns resembling the yew topiary of English gardens. Some limited use of T. brevifolia as an ornamental indicates it also has potential as a shade tree, for hedges, and for topiary (23,44).

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Vegetative Reproduction

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Pacific yew is capable of layering and often sprouts from stumps or rootstocks after the top has been killed or the tree cut (3,11,23,44). Layering usually occurs after branches or tree tops have been pressed to the ground for a prolonged period by large fallen trees or limbs (11), although occasional old yew trees can be found surrounded by a ring of well rooted branches that were apparently held down only by their own weight and the weight of snow in the winter.

Although Pacific yew is sensitive to heat (11,26,44), sprouts that originated from the bases of burned stumps were reported from the Rogue River National Forest in southern Oregon (23). Young yew trees that originated by layering and sprouting were observed in a sunny, south-facing clearcut on the Mount Hood National Forest in northern Oregon. From one cut yew tree with a stump diameter of 30 cm (12 in), seven new trees had originated by layering before cutting, and a clump of vigorous stump sprouts had originated after cutting. Sprouts emerged from one side of the 36-cm-high (14 in) stump (the opposite side had been debarked during logging) from ground level to the top. The layers were 1.0 m to 2.5 m (3 ft to 8 ft) from the stump. Most of the layers had been damaged by logging and lacked the vigor of the stump sprouts (3).

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Distribution

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Pacific yew grows in forests from the southern tip of southeast Alaska- including Annette and Prince of Wales Island- south through the Pacific Coast region of British Columbia, Vancouver and the Queen Charlotte Islands, and the Olympic Peninsula of Washington. It is rare in the Coast Range south of the Olympic Peninsula in Washington and north of the Umpqua River in Oregon, but occurs with greater frequency in the Coast Range in southern Oregon and northern California. Isolated occurrences are found as far south as Marin and San Mateo Counties in California. Yew occurs in scattered localities in the valleys between the Coast Range and Cascade Ranges of Oregon and Washington. In the Cascade Range, it is fairly common at low to moderate elevations, and on some sites in southern Oregon it is abundant. Pacific yew extends south through the Klamath Mountains of California, then southeasterly to the western slopes of the Sierra Nevada. Its southern limit is in Calaveras County. Farther inland, it grows on the western slopes of the Rocky Mountains in British Columbia, south into northern Idaho and western Montana, the Lewis Range in Montana, and isolated areas in eastern Washington and northeastern Oregon. In the South Fork of the Clearwater River basin in Idaho, Pacific yew deviates from its role as a minor forest component and becomes a dominant on about 16 000 hectares (40,000 acres) (8,19,20,27,30,31,35,40,42,43, 44,47,49).


- The native range of Pacific yew.

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Brief Summary

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Taxaceae -- Yew family

Charles L. Bolsinger and Annabelle E. Jaramillo

Pacific yew (Taxus brevifolia), also called western yew, is a coniferous tree associated with several conifer and hardwood tree species on a variety of sites. Pacific yew tolerates shade, and in undisturbed stands is usually found as an understory tree. Growth of such trees is slow, but where the overstory has been removed or thinned, diameter growth on undamaged yew trees may increase considerably. Pacific yew rarely exceeds 60 cm (24 in) in d.b.h., and 15 m (49 ft) in height. The largest on record is 142 cm (56 in) in d.b.h., and 18 m (60 ft) in height (28). The wood is hard, heavy, and resistant to decay. Although not of great interest to the forest products industry, it has many special uses. The bark of Pacific yew contains a drug, taxol, that is being used in cancer research, so demand for yew bark by the National Cancer Institute has increased dramatically in recent years (9).

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Physical Description

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Tree, Shrub, Evergreen, Dioecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots in flat sprays, Young shoots 3-dimensional, Buds not resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins entire (use magnification), Leaf apex acute, Leaf apex mucronulate, Leaves < 5 cm long, Leaves < 10 cm long, Leaves yellow-green below, Leaves not blue-green, Scale leaves without raised glands, Needle-like leaves flat, Needle-like leaves not twisted, Needle-like leaf habit erect, Needle-like leaf habit drooping, Needle-like leaves per fascicle mostly 1, Twigs glabrous, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Seeds within cone, Aril light green, Aril red to orange to purple, Berry-like cones reddish, Bracts of seed cone included, Seeds brown, Seeds wingless.
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Taxus brevifolia

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Taxus brevifolia, the Pacific yew[4] or western yew, is a conifer native to the Pacific Northwest of North America. It ranges from southernmost Alaska south to central California, mostly in the Pacific Coast Ranges, but with isolated disjunct populations in southeast British Columbia (most notably occurring on Zuckerberg Island near Castlegar) and in north to central Idaho.[5][6][7][8][9][10]

Characteristics

The Pacific yew is a small to medium-sized evergreen tree, growing 10–15 m tall and with a trunk up to 50 cm diameter, rarely more. In some instances, trees with heights in excess of 20 m occur in parks and other protected areas, quite often in gullies. The tree is extremely slow growing, and has a habit of rotting from the inside, creating hollow forms. This makes it difficult and sometimes impossible to make accurate rings counts to determine a specimen's true age. Often damaged by succession of the forest, it usually ends up in a squat, multiple leader form.

It has thin scaly brown bark, covering a thin layer of off-white sap wood with a darker heartwood that varies in color from brown to a magenta/purplish hue to deep red. The leaves are lanceolate, flat, dark green, 1–3 cm long and 2–3 mm broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem except on erect leading shoots where the spiral arrangement is more obvious.

The seed cones are highly modified, each cone containing a single seed 4–7 mm long partly surrounded by a modified scale which develops into a soft, bright red berry-like structure called an aril, 8–15 mm long and wide and open at the end. The arils are mature 6–9 months after pollination. The seeds contained in the arils are eaten by thrushes and other birds, which disperse the hard seeds undamaged in their droppings; maturation of the arils is spread over 2–3 months, increasing the chances of successful seed dispersal. The male cones are globose, 3–6 mm diameter, and shed their pollen in early spring. It is mostly dioecious, but occasional individuals can be variably monoecious, or change sex with time.

Habitat

Pacific yew grows in varying types of environments; however, in drier environments it is mostly limited to stream side habitats, whereas in moist environments it will grow up onto slopes and ridgetops.[5] Pacific yew is shade tolerant; however it can also grow in sun.[11] The tree's shade tolerance allows it to form an understory, which means that it can grow along streams providing shade to maintain water temperature.[12]

Varieties of Pacific yew (Taxus brevifolia)

Taxus brevifolia var. reptaneta. Although T. brevifolia is typically a tree as described above, T. brevifolia var. reptaneta is a shrub variety that generally occurs in the mid to upper elevation range of the typical variety, 3,500 to 4,000 ft (1000–1219 m) at its southernmost occurrence in the Klamath Mountains region, and at lower elevations further north.[13] It is distinguished from young trees of the typical variety (var. brevifolia) by its stems initially creeping along the ground for a short distance before ascending (curving) upwards and by the branches growing off to one side of the stem, usually the upper side.[14] The epithet reptaneta is from the Latin reptans which means “creeping, prostrate, and rooting,”[15] which is exactly what this variety does; in rooting it forms yew thickets; hence, the epithet reptaneta (etum means collective place of growth) and hence the common name, thicket yew. Unlike the typical variety, thicket yew grows in abundance on open sunny avalanche shoots or ravines as well as in the forest understory. It also occurs along forest margins. In northwestern Montana, a variant of the thicket yew does not ascend upwards; rather, it remains along the ground.[13] This is probably the ancestral form; the upright form with branches along the upper side would be the expected growth pattern that might evolve from one with stems that strictly creep along the ground since branches can only arise from the upper surface.

Taxus brevifolia var. reptaneta has been arbitrarily indicated synonymous with typical yew, T. brevifolia (var. brevifolia); there are no studies to support this view. Even though the two varieties may be genetically distinct, some botanists recognize species or varieties only if they have different geographically ranges. For example, T. mairei var. speciosa, which occurs with the typical variety in southern China in 10 of 13 provinces, was rejected because “there is no geographic reason” for recognizing it[16] even though it appears genetically distinct.[17]

Taxus brevifolia var. reptaneta has also been proposed to be elevated to subspecies status without justification or explanation. Such a change would likely cause considerable confusion in view of the subspecies rank having already been used in the genus Taxus for defining geographically separated subspecies of a single species (T. baccata).[18] Further, it has been recommended that taxonomists be strongly discouraged from “elevating a ‘variety’ to a ‘subspecies’ unless there is sufficient scientific evidence to warrant such an elevation,” and that “it is crucial to provide continuity.”[19]

Taxus brevifolia var. polychaeta. Typical Taxus brevifolia, like most species in the genus, usually produces a single ovule on a complex scaly shoot, composed of a primary shoot and a secondary short shoot. To the casual observer they appear as one funnelform shoot with an ovule at the apex.[20] However, Taxus brevifolia var. polychaeta differs from var. brevifolia in producing a relatively longer primary shoot[13] with as many five secondary shoots.[21] The epithet, polychaeta, is in reference to the primary shoot resembling a polychaete worm; hence, its common name 'worm cone yew'. Variety polychaeta appears to be relatively rare. It may have been extirpated from the type locality—around Mud Bay near Olympia, Washington—as a result of urban expansion. It is also known from northern Idaho and Sonoma County, California.[13][22]

As in the case with thicket yew, worm yew has been indicated to be the same as the typical variety, but again there are no specific studies to support this conclusion. The authority of thicket yew and worm cone yew has been involved in the study of the genus Taxus for 25 years at the time the varieties were described.[13][23]

Uses

Traditionally, the wood was used by Native Americans to make bows and paddles for canoes, in addition many other items from daily life.[24] The Japanese have also used the wood for decorative purposes.[5]

Members of the Pit River Tribe would sell this plant to the Ukiah.[25]

The Concow tribe calls the tree yōl’-kō (Konkow language)[26]

While many parts of yews are poisonous and can be fatal if eaten, the juicy red cup around the seed seems to be edible as long as the seed within is not chewed or swallowed. Birds eat such cups and spread the seeds.[27]

Discovery of taxol

The chemotherapy drug paclitaxel (taxol), used in breast, ovarian, and lung cancer treatment, is derived from Taxus brevifolia. As it was already becoming scarce when its chemotherapeutic potential was realized, the Pacific yew was never commercially harvested from its habitat at a large scale; the widespread use of the paclitaxel (taxol) was enabled when a semi-synthetic pathway was developed from extracts of cultivated yews of other species.[28] Unlicensed pharmaceutical production use of closely related wild yew species in India and China may be threatening some of those species.[29]

Gallery

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    Pacific Yew foliage underside

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    Pacific Yew form

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    Pacific Yew foliage

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    Pacific Yew mat form

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    Pacific Yew bark

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    Color variations of bark on Pacific yew

References

  1. ^ Conifer Specialist Group (1998). "Taxus brevifolia". IUCN Red List of Threatened Species. IUCN. 1998. Retrieved 5 May 2006.old-form url
  2. ^ Tropicos
  3. ^ The Plant List
  4. ^ "Taxus brevifolia". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 8 December 2015.
  5. ^ a b c Bolsinger, Charles; Jaramillo, Annabelle (1990). Russell M Burns; Barbara H. Honkala (eds.). "Taxus brevifolia Nutt. - Pacific Yew". Silvics of North America (Agriculture Handbook #654). USDA, USFS. 1 - Conifers: 573–579. Retrieved April 26, 2018."Free
  6. ^ Hitchcock, C. H., A.J. Cronquist, F. M. Ownbey & J. W. Thompson. 1969. Vascular Cryptogams, Gymnosperms, and Monocotyledons. 1: 1–914. In C. L. Hitchcock Vascular Plants of the Pacific Northwest. University of Washington Press, Seattle.
  7. ^ Hultén, E. 1968. Flora Alaska i–xxi, 1–1008. Stanford University Press, Stanford.
  8. ^ Moss, E. H. 1983. Flora of Alberta (ed. 2) i–xii, 1–687. University of Toronto Press, Toronto.
  9. ^ Munz, P. A. & D. D. Keck. 1959. California Flora 1–1681. University of California Press, Berkeley.
  10. ^ Welsh, S. L. 1974. Anderson's Flora of Alaska and Adjacent Parts of Canada i–xvi, 1–724. Brigham Young University Press, Provo.
  11. ^ Mitchell, A. "Acclimation of Pacific yew (Taxus brevifolia) foliage to sun and shade". Tree Physiology. 18.
  12. ^ Scher, Stanley; Schwarzschild, Bert (1989). "Pacific Yew: a Faculative Riparian Conifer with an Uncertain Future" (PDF).
  13. ^ a b c d e Spjut, R. W. 2007. Taxonomy and nomenclature of Taxus. J. Bot. Res. Inst. Texas 1(1): 203–289.
  14. ^ Web page, World Botanical Associates, Taxus brevifolia var. reptaneta; http://www.worldbotanical.com/taxus_brevifolia_var_reptaneta.htm. Retrieved 9 Dec 2014
  15. ^ Stearn, W. T. 1983. Botanical Latin. 3rd ed. David & Charles, London
  16. ^ Möller M, Gao L-M, Mill RR, Liu J, Zhang D-Q, Poudel RC, Li D-Z, 2013. A multidisciplinary approach reveals hidden taxonomic diversity in the morphologically challenging Taxus wallichiana complex. Taxon 62: 1161–1177.
  17. ^ Gao L-M, Möller M, Zhang X-M, Hollingsworth ML, Liu J, Mill RR, Gibby M, Li D-Z, 2007. High variation and strong phylogeographic pattern among cpDNA haplotypes in Taxus wallichiana (Taxaceae) in China and North Vietnam. Molec. Ecol. 16: 4684–4698.
  18. ^ Pilger R, 1903. Taxaceae-Taxoideae—Taxeae. Taxus. In: Das Pflanzenreich IV (Engler A. ed.): 110–116.
  19. ^ Ellison AM, Davis CC, Calie PJ, Naczi RFC, 2014. Pitcher plants (Sarracenia) provide a 21st-century perspective on infraspecific ranks and interspecific hybrids: A modest proposal for appropriate recognition and usage. Syst. Bot. 39: 939–949.
  20. ^ Florin R, 1951. Evolution in cordaites and conifers. Acta Horti Berg. 16: 285–388, plate
  21. ^ Web page, World Botanical Associates, Overview of the genus Taxus, http://www.worldbotanical.com/TAXNA.HTM, retrieved 9 Dec 2014
  22. ^ Web page, World Botanical Associates, Taxus brevifolia var. polychaeta; http://www.worldbotanical.com/taxus_brevifolia_var_polychaeta.htm; retrieved 9 Dec 2014
  23. ^ Spjut, R. W. 1977. USDA, ARS Memorandum, July 14]. Taxus brevifolia (Taxaceae) reviewed by GMC (Gudrun M. Christensen). A review of literature on taxonomy, ecology, and geographical distribution of the species, including its description, summary of geographical distribution by state or province, and literature reviewed. Distributed periodically during 1981-1992 by the National Cancer Institute to prospective suppliers, without reference to the author, for solicitations of contract bids on up to 30 tons of bark.
  24. ^ Hansen, Robert (ed.). "Taxus and Taxol - A Compilation of Research Findings".
  25. ^ Chestnut, V. K. 1902 Plants Used by the Indians of Mendocino County, California. Contributions from the U.S. National Herbarium 7:295-408. (p. 305)
  26. ^ Chesnut, Victor King (1902). Plants used by the Indians of Mendocino County, California. Government Printing Office. p. 408. Retrieved 24 August 2012.
  27. ^ Whitney, Stephen (1985). Western Forests (The Audubon Society Nature Guides). New York: Knopf. p. 364. ISBN 0-394-73127-1.
  28. ^ Young; et al. (2017). "Evaluating the impact of paclitaxel on Tacus brevifola distribution". Journal of Applied Ecology. 34 (11): 87–95.
  29. ^ BGCI, ‘Miracle’ Cures Face Extinction, retrieved 2008-07-21
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Taxus brevifolia: Brief Summary

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Taxus brevifolia, the Pacific yew or western yew, is a conifer native to the Pacific Northwest of North America. It ranges from southernmost Alaska south to central California, mostly in the Pacific Coast Ranges, but with isolated disjunct populations in southeast British Columbia (most notably occurring on Zuckerberg Island near Castlegar) and in north to central Idaho.

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