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Brief Summary

Hound's tongue produces flat barbed seedlings. Many fur-coated animals, such as rabbits, help spread these burrs. People's clothing also serves this purpose well. Hound's tongue is poisonous and was used in earlier days for healing infections. Due to its toxicity, the plant and as well as the seeds are not grazed by animals. However, that doesn't keep away various moths and trunk beetles. Hound's tongue grows in sunny, light areas and loose, calcium-rich soil. In the Netherlands, it is limited to the dunes in North and South Holland.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Copyright Ecomare

Source: Ecomare


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National Distribution


Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe


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More info for the term: natural

The center of origin of houndstongue is thought to be the mountains of western Asia and eastern Europe. Houndstongue also occurs in apparently natural communities in Great Britain. It is widely distributed through Europe, where its northern limit is approximately 60°N, though there are isolated occurrences up to 68°N in Sweden. Towards the Mediterranean region it becomes rare. Houndstongue does not grow in the southernmost regions of Europe [26].

A review by Upadhyaya and others [99] suggests houndstongue was introduced to North America as a crop seed contaminant from Europe. Herbarium specimens of houndstongue were collected in Ontario as early as 1859 and in the western provinces between 1922 and 1934. Houndstongue was noted in 1884 as "common" around Montreal, and as "a pest" in Ontario. As of 1988, houndstongue occurred in all provinces in Canada except Prince Edward Island and Newfoundland, and appeared to be most abundant in southern British Columbia and Ontario. Houndstongue occurs throughout the contiguous U.S., in all but 6 southern states. Its occurrence has not been reported in Alaska or Hawaii [96]. Houndstongue is reported as a problem plant in natural areas and parks in several states including Michigan, Missouri, Indiana [73], Colorado, and Oregon [80]. The Plants database provides a distribution map of houndstongue in the United States.

The following biogeographic classification systems are presented as a guide to demonstrate where houndstongue may be found. Precise distribution information is limited. Because it is so widespread and has broad ecological tolerances, it is difficult to exclude many ecosystems as potential hosts of houndstongue plants or populations. Therefore, these lists are speculative and not necessarily exhaustive.


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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

3 Southern Pacific Border

4 Sierra Mountains

5 Columbia Plateau

6 Upper Basin and Range

7 Lower Basin and Range

8 Northern Rocky Mountains

9 Middle Rocky Mountains

10 Wyoming Basin

11 Southern Rocky Mountains

12 Colorado Plateau

13 Rocky Mountain Piedmont

14 Great Plains

15 Black Hills Uplift

16 Upper Missouri Basin and Broken Lands


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Occurrence in North America

STATES [49]:




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Physical Description



More info for the term: forb

Houndstongue is a biennial or short-lived perennial forb. The following description of houndstongue is based on reviews by Upadhyaya and others [99] and de Jong and others [26]. It presents characteristics of houndstongue that may be relevant to fire ecology, and is not meant to be used for identification. Keys for identification are available [17,35,37,42,43,63,104,107]. A detailed discussion of the biology of houndstongue is provided by de Jong and others [26].

Houndstongue forms a rosette in its 1st year with softly pubescent leaves 4 to 12 inches (10-30 cm) long and 0.8 to 2 inches (2-5 cm) wide. It has a thick, black, branching taproot, extending to depths > 40 inches (100 cm). An individual plant consists of 1 or several rosettes on a single root system. Flower stems, 12 to 48 inches (30-120 cm) tall, are produced the 2nd year, or sometimes later. The upper part of the stem is branching. Stem leaves are generally broadest near the base and narrower towards the tip. Houndstongue inflorescences have up to 35 but usually no more than 10 flowers each and are axillary to leaves or terminating short branches. Each flower can produce up to 4 fruits. The fruits are nutlets, the surfaces of which are flat and densely covered with small, barbed hooks (glochidia) that facilitate dispersal by animals.

Houndstongue rosettes can withstand drought stress, enabling the plant to survive water deficits and to delay flowering until conditions are favorable. The thick, deep taproot can exploit lower soil strata for water and nutrients. The root also serves as an underground food reserve which may offer protection against winter injury [11,98,99].

Houndstongue often occurs in dense stands, but may also occur as a small but regular proportion of regional flora. Seedlings are usually strongly clustered around parent plants in densities of up to 405 seedlings per ft2 (4500/m2) [26]. Houndstongue may grow as an isolated plant or at densities up to 1 individual per ft2 (8/m2) on dunes in England. On coastal dunes in the Netherlands, its abundance ranges from rare to abundant. Vesicular-arbuscular mycorrhizae are usually present on houndstongue roots [26,39].


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Habitat characteristics

More info for the term: peat

In North America, houndstongue often occurs in "waste" areas [63,104] and disturbed sites (especially roadsides) [17,37,42,67], including logging roads and heavily grazed areas [20,60], disturbed woods and forest clearings [104,106], and lake shores [104]. Dense infestations of houndstongue are found in clearcut areas in northern British Columbia [99], and Upadhyaya and Cranston [98] suggest that houndstongue thrives and has great potential for spread in areas disturbed by logging operations and road construction.

Houndstongue is most abundant in areas with more than 10% bare ground (review by [99]). Studies in Europe also indicate that houndstongue requires open, disturbed ground and that it is most common in dry, open habitats [26], such as the dune grasslands in England. Houndstongue can exploit bare ground around rabbit warrens, benefiting from the high nitrogen levels from rabbit excreta, and the fact that rabbits do not usually eat houndstongue. Houndstongue is often found in areas grazed by livestock and wildlife [20,74,81].

In England and in the Netherlands, houndstongue occurs on sand dunes and calcareous substrates. These calcareous, sandy soils have high nitrate levels that favor houndstongue establishment, and abundant calcium that houndstongue accumulates to a marked degree, especially in its leaves [11]. Houndstongue is absent from acid coastal dunes and from acid sandy soils and does not occur on peat or clay soils [99]. In Germany houndstongue grows on both calcium-rich and weakly-acid soil, and is classified as both a drought and nitrogen indicator [26]. In British Columbia it is found on soils ranging from well-drained, relatively coarse material to clay subsoils in the open coniferous and deciduous forests. In Eastern Canada, houndstongue is often associated with rocky pastures in limestone regions [98].

Houndstongue is found in temperate regions. In British Columbia it is found on sites that are characterized by hot, dry summers and cold winters, with annual precipitation in the range of 11 to 18 inches (268-448 mm), and mean January and July temperatures of approximately 21 and 72 degrees Fahrenheit (-6 and 22 ºC), respectively. In Ontario, houndstongue-infested regions have annual precipitation and mean January and July temperature variations in the range of 31 to 41 inches (770-1020 mm), 39 to 52 degrees Fahrenheit (3.9-10.9 ºC) and 67 to 72 degrees Fahrenheit (19.2-22.2 ºC), respectively [99]. On droughty sand dunes in the Netherlands, the amount of rainfall during the growing season greatly affects growth, survival and seed production in houndstongue. Here the species may disappear from the most exposed sites after several dry years, and recolonize these areas again after a number of wet years. Plants grow poorly and eventually die after waterlogging [26]. Houndstongue is not well adapted to dry grassland sites with less than 12 inches (300 mm) annual precipitation in British Columbia. It survives well in wetter grasslands and moist draws in drier sites [98].

The distribution pattern of houndstongue in Europe suggests that at its northern limits its temperature requirements during the growing season, rather than the occurrence of winter frost, restrict the species to warmer microsites. On sand dunes in England, it occurs mostly on south or south-east facing slopes [26]. Houndstongue is completely absent from areas above 495 feet (150 m) in England. In continental Europe, it reaches the subalpine but only rarely the alpine (4,950 to 7,920 feet (1,500-2,400 m)). Some elevational ranges at which houndstongue occurs are given below:

State Elevation range Reference
UT 4,880 to 9,900 feet (1,480-3,000 m) [107]
CA 2,800 to 3,300 feet (850-1,000 m) [42]
NM 5,000 to 8,000 feet (1,500-2,400 m) [63]


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Habitat: Rangeland Cover Types

More info on this topic.

This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, hardwood, shrub, vine


101 Bluebunch wheatgrass

102 Idaho fescue

103 Green fescue

104 Antelope bitterbrush-bluebunch wheatgrass

105 Antelope bitterbrush-Idaho fescue

106 Bluegrass scabland

107 Western juniper/big sagebrush/bluebunch wheatgrass

108 Alpine Idaho fescue

109 Ponderosa pine shrubland

110 Ponderosa pine-grassland

201 Blue oak woodland

202 Coast live oak woodland

203 Riparian woodland

204 North coastal shrub

205 Coastal sage shrub

206 Chamise chaparral

207 Scrub oak mixed chaparral

208 Ceanothus mixed chaparral

209 Montane shrubland

210 Bitterbrush

211 Creosote bush scrub

212 Blackbush

213 Alpine grassland

214 Coastal prairie

215 Valley grassland

216 Montane meadows

301 Bluebunch wheatgrass-blue grama

302 Bluebunch wheatgrass-Sandberg bluegrass

303 Bluebunch wheatgrass-western wheatgrass

304 Idaho fescue-bluebunch wheatgrass

305 Idaho fescue-Richardson needlegrass

306 Idaho fescue-slender wheatgrass

307 Idaho fescue-threadleaf sedge

308 Idaho fescue-tufted hairgrass

309 Idaho fescue-western wheatgrass

310 Needle-and-thread-blue grama

311 Rough fescue-bluebunch wheatgrass

312 Rough fescue-Idaho fescue

313 Tufted hairgrass-sedge

314 Big sagebrush-bluebunch wheatgrass

315 Big sagebrush-Idaho fescue

316 Big sagebrush-rough fescue

317 Bitterbrush-bluebunch wheatgrass

318 Bitterbrush-Idaho fescue

319 Bitterbrush-rough fescue

320 Black sagebrush-bluebunch wheatgrass

321 Black sagebrush-Idaho fescue

322 Curlleaf mountain-mahogany-bluebunch wheatgrass

323 Shrubby cinquefoil-rough fescue

324 Threetip sagebrush-Idaho fescue

401 Basin big sagebrush

402 Mountain big sagebrush

403 Wyoming big sagebrush

404 Threetip sagebrush

405 Black sagebrush

406 Low sagebrush

407 Stiff sagebrush

408 Other sagebrush types

409 Tall forb

410 Alpine rangeland

411 Aspen woodland

412 Juniper-pinyon woodland

413 Gambel oak

414 Salt desert shrub

415 Curlleaf mountain-mahogany

416 True mountain-mahogany

417 Littleleaf mountain-mahogany

418 Bigtooth maple

419 Bittercherry

420 Snowbrush

421 Chokecherry-serviceberry-rose

422 Riparian

501 Saltbush-greasewood

502 Grama-galleta

503 Arizona chaparral

504 Juniper-pinyon pine woodland

505 Grama-tobosa shrub

506 Creosotebush-bursage

507 Palo verde-cactus

508 Creosotebush-tarbush

509 Transition between oak-juniper woodland and mahogany-oak association

601 Bluestem prairie

602 Bluestem-prairie sandreed

603 Prairie sandreed-needlegrass

604 Bluestem-grama prairie

605 Sandsage prairie

606 Wheatgrass-bluestem-needlegrass

607 Wheatgrass-needlegrass

608 Wheatgrass-grama-needlegrass

609 Wheatgrass-grama

610 Wheatgrass

611 Blue grama-buffalo grass

612 Sagebrush-grass

613 Fescue grassland

614 Crested wheatgrass

615 Wheatgrass-saltgrass-grama

701 Alkali sacaton-tobosagrass

702 Black grama-alkali sacaton

703 Black grama-sideoats grama

704 Blue grama-western wheatgrass

705 Blue grama-galleta

706 Blue grama-sideoats grama

707 Blue grama-sideoats grama-black grama

708 Bluestem-dropseed

709 Bluestem-grama

710 Bluestem prairie

711 Bluestem-sacahuista prairie

712 Galleta-alkali sacaton

713 Grama-muhly-threeawn

714 Grama-bluestem

715 Grama-buffalo grass

716 Grama-feathergrass

717 Little bluestem-Indiangrass-Texas wintergrass

718 Mesquite-grama

720 Sand bluestem-little bluestem (dunes)

721 Sand bluestem-little bluestem (plains)

722 Sand sagebrush-mixed prairie

723 Sea oats

724 Sideoats grama-New Mexico feathergrass-winterfat

725 Vine mesquite-alkali sacaton

727 Mesquite-buffalo grass

729 Mesquite

733 Juniper-oak

801 Savanna

802 Missouri prairie

803 Missouri glades

804 Tall fescue

805 Riparian

809 Mixed hardwood and pine


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Habitat: Cover Types

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):

More info for the term: cover


1 Jack pine

5 Balsam fir

12 Black spruce

13 Black spruce-tamarack

14 Northern pin oak

15 Red pine

16 Aspen

17 Pin cherry

18 Paper birch

19 Gray birch-red maple

20 White pine-northern red oak-red maple

21 Eastern white pine

22 White pine-hemlock

23 Eastern hemlock

24 Hemlock-yellow birch

25 Sugar maple-beech-yellow birch

26 Sugar maple-basswood

27 Sugar maple

28 Black cherry-maple

30 Red spruce-yellow birch

31 Red spruce-sugar maple-beech

32 Red spruce

33 Red spruce-balsam fir

34 Red spruce-Fraser fir

35 Paper birch-red spruce-balsam fir

37 Northern white-cedar

38 Tamarack

39 Black ash-American elm-red maple

40 Post oak-blackjack oak

42 Bur oak

43 Bear oak

44 Chestnut oak

46 Eastern redcedar

49 Pitch pine

50 Black locust

51 White pine-chestnut oak

52 White oak-black oak-northern red oak

53 White oak

55 Northern red oak

57 Yellow-poplar

58 Yellow-poplar-eastern hemlock

59 Yellow-poplar-white oak-northern red oak

60 Beech-sugar maple

61 River birch-sycamore

62 Silver maple-American elm

63 Cottonwood

64 Sassafras-persimmon

65 Pin oak-sweetgum

71 Longleaf pine-scrub oak

72 Southern scrub oak

78 Virginia pine-oak

82 Loblolly pine-hardwood

85 Slash pine-hardwood

93 Sugarberry-American elm-green ash

94 Sycamore-sweetgum-American elm

95 Black willow

107 White spruce

108 Red maple

109 Hawthorn

110 Black oak

201 White spruce

202 White spruce-paper birch

203 Balsam poplar

204 Black spruce

205 Mountain hemlock

206 Engelmann spruce-subalpine fir

207 Red fir

208 Whitebark pine

209 Bristlecone pine

210 Interior Douglas-fir

211 White fir

212 Western larch

213 Grand fir

215 Western white pine

216 Blue spruce

217 Aspen

218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

221 Red alder

222 Black cottonwood-willow

223 Sitka spruce

224 Western hemlock

225 Western hemlock-Sitka spruce

226 Coastal true fir-hemlock

227 Western redcedar-western hemlock

228 Western redcedar

229 Pacific Douglas-fir

230 Douglas-fir-western hemlock

231 Port-Orford-cedar

232 Redwood

233 Oregon white oak

234 Douglas-fir-tanoak-Pacific madrone

235 Cottonwood-willow

236 Bur oak

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

240 Arizona cypress

241 Western live oak

243 Sierra Nevada mixed conifer

244 Pacific ponderosa pine-Douglas-fir

245 Pacific ponderosa pine

246 California black oak

247 Jeffrey pine

248 Knobcone pine

249 Canyon live oak

250 Blue oak-foothills pine

251 White spruce-aspen

252 Paper birch

253 Black spruce-white spruce

254 Black spruce-paper birch

255 California coast live oak

256 California mixed subalpine


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Habitat: Plant Associations

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

More info for the term: shrub


K001 Spruce-cedar-hemlock forest

K002 Cedar-hemlock-Douglas-fir forest

K003 Silver fir-Douglas-fir forest

K004 Fir-hemlock forest

K005 Mixed conifer forest

K006 Redwood forest

K007 Red fir forest

K008 Lodgepole pine-subalpine forest

K009 Pine-cypress forest

K010 Ponderosa shrub forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K013 Cedar-hemlock-pine forest

K014 Grand fir-Douglas-fir forest

K015 Western spruce-fir forest

K016 Eastern ponderosa forest

K017 Black Hills pine forest

K018 Pine-Douglas-fir forest

K019 Arizona pine forest

K020 Spruce-fir-Douglas-fir forest

K021 Southwestern spruce-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K025 Alder-ash forest

K026 Oregon oakwoods

K027 Mesquite bosques

K028 Mosaic of K002 and K026

K029 California mixed evergreen forest

K030 California oakwoods

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K033 Chaparral

K034 Montane chaparral

K035 Coastal sagebrush

K036 Mosaic of K030 and K035

K037 Mountain-mahogany-oak scrub

K038 Great Basin sagebrush

K039 Blackbrush

K040 Saltbush-greasewood

K041 Creosote bush

K042 Creosote bush-bur sage

K043 Paloverde-cactus shrub

K044 Creosote bush-tarbush

K045 Cenzia shrub

K046 Desert: vegetation largely lacking

K047 Fescue-oatgrass

K048 California steppe

K050 Fescue-wheatgrass

K051 Wheatgrass-bluegrass

K052 Alpine meadows and barren

K053 Grama-galleta steppe

K054 Grama-tobosa prairie

K055 Sagebrush steppe

K056 Wheatgrass-needlegrass shrubsteppe

K057 Galleta-threeawn shrubsteppe

K058 Grama-tobosa shrubsteppe

K059 Trans-Pecos shrub savanna

K063 Foothills prairie

K064 Grama-needlegrass-wheatgrass

K065 Grama-buffalo grass

K066 Wheatgrass-needlegrass

K067 Wheatgrass-bluestem-needlegrass

K068 Wheatgrass-grama-buffalo grass

K069 Bluestem-grama prairie

K070 Sandsage-bluestem prairie

K072 Sea oats prairie

K074 Bluestem prairie

K075 Nebraska Sandhills prairie

K076 Blackland prairie

K077 Bluestem-sacahuista prairie

K081 Oak savanna

K082 Mosaic of K074 and K100

K083 Cedar glades

K084 Cross Timbers

K085 Mesquite-buffalo grass

K088 Fayette prairie

K089 Black Belt

K093 Great Lakes spruce-fir forest

K095 Great Lakes pine forest

K096 Northeastern spruce-fir forest

K097 Southeastern spruce-fir forest

K098 Northern floodplain forest

K099 Maple-basswood forest

K100 Oak-hickory forest

K101 Elm-ash forest

K102 Beech-maple forest

K103 Mixed mesophytic forest

K104 Appalachian oak forest

K106 Northern hardwoods

K107 Northern hardwoods-fir forest

K108 Northern hardwoods-spruce forest

K109 Transition between K104 and K106

K110 Northeastern oak-pine forest


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Habitat: Ecosystem

More info on this topic.

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):


FRES10 White-red-jack pine

FRES11 Spruce-fir

FRES14 Oak-pine

FRES15 Oak-hickory

FRES16 Oak-gum-cypress

FRES17 Elm-ash-cottonwood

FRES18 Maple-beech-birch

FRES19 Aspen-birch

FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES22 Western white pine

FRES23 Fir-spruce

FRES24 Hemlock-Sitka spruce

FRES25 Larch

FRES26 Lodgepole pine

FRES27 Redwood

FRES28 Western hardwoods

FRES29 Sagebrush

FRES30 Desert shrub

FRES33 Southwestern shrubsteppe

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES36 Mountain grasslands

FRES37 Mountain meadows

FRES38 Plains grasslands

FRES39 Prairie

FRES40 Desert grasslands

FRES42 Annual grasslands

FRES44 Alpine


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Key Plant Community Associations

In British Columbia, houndstongue occurs predominantly in the Interior
Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus
ponderosa)-bunchgrass biogeoclimatic zones [99].

In Utah, houndstongue may be found in
sagebrush (Artemisia spp.), pinyon-juniper (Pinus spp.-Juniperus
spp.), cottonwood (Populus spp.),
mountain brush, quaking aspen (Populus tremuloides), ponderosa pine, and spruce-fir
(Picea spp.-Abies spp.) communities [107]. It is a minor component in
Gambel oak
(Quercus gambelii) communities in central and northern Utah [58]. On preserves in Colorado, houndstongue has been reported in
shortgrass prairie, narrowleaf cottonwood/red-osier dogwood (Populus
angustifolia/Cornus sericea) riparian forests, and riparian meadows.

In northeastern Oregon, houndstongue invades Idaho fescue (Festuca
idahoensis), bluebunch wheatgrass (Pseudoroegneria spicata), and
prairie Junegrass (Koeleria macrantha) grasslands, and riparian habitats
In Iowa, houndstongue was found on an upland site dominated by white oak (Q.
alba), northern red oak (Q. rubra), and shagbark hickory (Carya ovata) [54].


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Flower-Visiting Insects of Common Hound's Tongue in Illinois

Cynoglossum officinale (Common Hound's Tongue) introduced
(Bees suck nectar; this observation is from Robertson)

Bees (long-tongued)
Megachilidae (Megachilini): Megachile brevis brevis sn
Insect activities:
sn = sucks nectar


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Flower-Visiting Insects of Common Hound's Tongue in Illinois

Cynoglossum officinale (Common Hound's Tongue) introduced
(Bees suck nectar; this observation is from Robertson)

Bees (long-tongued)
Megachilidae (Megachilini): Megachile brevis brevis sn


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In Great Britain and/or Ireland:
Foodplant / parasite
cleistothecium of Golovinomyces cynoglossi parasitises live Cynoglossum officinale

Foodplant / open feeder
adult of Longitarsus anchusae grazes on leaf of Cynoglossum officinale

Foodplant / open feeder
adult of Longitarsus exoletus grazes on leaf of Cynoglossum officinale

Foodplant / open feeder
adult of Longitarsus quadriguttatus grazes on leaf of Cynoglossum officinale
Other: major host/prey

Foodplant / feeds on
Mogulones asperifoliarum feeds on Cynoglossum officinale

Foodplant / spot causer
mainly epiphyllous colony of Ramularia hyphomycetous anamorph of Ramularia cynoglossi causes spots on live leaf of Cynoglossum officinale
Other: major host/prey


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General Ecology

Fire Management Considerations

More info for the terms: cover, fire management, frequency, invasive species, natural, phenology, prescribed burn, restoration, wildfire

Fire as a control agent: Observations by managers suggest that a lack of normal ecological processes such as fire and flood can promote establishment by invasive plants such as houndstongue [80]. In some ecosystems, re-establishing historic FIRE REGIMES can be effective at controlling invasive species by encouraging growth and vigor of native species (e.g. [19,29,44,79]). Research is needed regarding the potential of prescribed burning to control houndstongue.

Postfire colonization potential: General precautions should be followed to prevent houndstongue establishment after fire. The USDA Forest Service's "Guide to noxious weed prevention practices" [95] provides several fire management considerations for weed prevention in general that can be applied to houndstongue. Wildfire managers might consider including weed prevention education and providing weed identification aids during fire training; avoiding known weed infestations when locating firelines, monitoring camps, staging areas, and helibases to be sure they are kept weed free; taking care that equipment is weed free; incorporating the cost of weed prevention and management into fire rehabilitation plans; and acquiring restoration funding. Careful postfire vigilance to identify and record the establishment of new populations is critical. About 1 month after fire, survey for signs of new or resprouting weeds. Repeat surveys will be needed, with the frequency and intensity of the survey guided by local conditions [7].

Potential weed problems must be addressed during prefire planning of prescribed burns, and following both wild and prescribed fires. When planning a prescribed burn, preinventory the project area, evaluate cover and phenology of any houndstongue present on or adjacent to the site, and evaluate the potential for increased houndstongue populations in the area [7]. Avoid ignition and burning in areas at high risk for weed establishment or spread, and/or plan for follow-up treatments in succeeding years. Avoid creating soil conditions that promote weed germination and establishment. Discuss weed status and risks in burn rehabilitation plans [95].

To prevent new infestations, re-establish vegetation on bare ground as soon after fire as possible, using either natural recovery or artificial techniques as appropriate to site conditions and objectives. When reseeding after wildfires and prescribed burns, use only certified weed-free seed. Monitor the burn site and associated disturbed areas after the fire and the following spring for emergence of houndstongue, and treat to eradicate any emergent houndstongue or other pestiferous plants. Regulate human, pack animal, and livestock entry into burned areas at risk for weed invasion until desirable site vegetation has recovered sufficiently to resist weed invasion. Additional guidelines and specific recommendations and requirements are available [7,36,95].


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Broad-scale Impacts of Plant Response to Fire

More info for the terms: prescribed fire, restoration

The Research Project Summary
Vegetation response to restoration treatments in ponderosa pine-Douglas-fir forests of western Montana
provides information on prescribed fire and postfire response of plant community species including


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Plant Response to Fire

More info for the terms: fire severity, invasive species, severity, wildfire

Response of invasive species such as houndstongue to fire will depend on the conditions of the fire such as fire severity, time of burning, prior and subsequent weather conditions [18], and composition of the preburn community and seed bank. Fire creates conditions that are suitable to houndstongue establishment; however, it is unclear how houndstongue plants or populations would respond to historic FIRE REGIMES on sites where it occurs. On a western juniper (J. occidentalis)/mountain mahogany (Cercocarpus spp.)/bluebunch wheatgrass site in northeastern Oregon, houndstongue established 5 years after a wildfire of moderate severity, and did not establish on a similar site that was severely burned [46].


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Immediate Effect of Fire

More info for the term: severity

Fire probably top-kills houndstongue plants. A high severity fire would probably be necessary to kill houndstongue because of its hardy taproot. Research is needed regarding the effects of fire on both houndstongue plants and seeds.


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Post-fire Regeneration

More info for the terms: crown residual colonizer, ground residual colonizer, initial off-site colonizer, secondary colonizer

Ground residual colonizer (on-site, initial community)
Crown residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community)
Secondary colonizer (on-site or off-site seed sources)


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Fire Ecology

More info for the terms: competition, fire exclusion, fire regime, historical fire regime, natural, presence, shrub

Fire adaptations: Houndstongue reproduces by seed, some of which may be dispersed over moderate to long distances by animals. Fire creates conditions that are favorable for establishment of houndstongue (i.e. open canopy, reduced competition, areas of bare soil), so if houndstongue seeds are present and competition minimal, it may be favored in the postfire community. Houndstongue plants may also survive fire, since nutrient reserves in the taproot acquired during the 1st year are sufficient for normal seed production the following year, even if the plants are completely defoliated early in the spring [11,98]. More research is needed regarding adaptations of houndstongue to fire.

FIRE REGIMES: Introduced species can alter the rate of spread of fire, the probability of occurrence of fire, and the intensity of fire in an ecosystem [18]. It is unclear how the presence of houndstongue may alter the fire regime of a given site, and it is unclear how a historical fire regime might affect the presence or abundance of houndstongue at a given site. It has been suggested that the exclusion or alteration of natural processes, such as fire and flooding, can encourage the establishment and persistence of houndstongue on prairie sites in Colorado [80]. Houndstongue did not occur in any of these communities at the time in which historic fire regimes were functioning, but has established since fire exclusion began. More information is needed about ecosystems in which houndstongue is likely to be invasive in North America.

The following table provides some fire return intervals for communities or ecosystems in which houndstongue may be found. Because houndstongue is widespread, it is difficult to exclude many ecosystems as potential hosts of houndstongue plants or populations.

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii > 200
grand fir A. grandis 35-200 [3]
maple-beech-birch Acer-Fagus-Betula > 1000
silver maple-American elm A. saccharinum-Ulmus americana
sugar maple A. saccharum > 1000
sugar maple-basswood A. s.-Tilia americana > 1000 [105]
California chaparral Adenostoma and/or Arctostaphylos spp. 72]
bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium 55,72]
Nebraska sandhills prairie A. g. var. paucipilus-S. s.
bluestem-Sacahuista prairie A. littoralis-Spartina spartinae
sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [72]
basin big sagebrush A. t. var. tridentata 12-43 [84]
mountain big sagebrush A. t. var. vaseyana 15-40 [4,13,66]
Wyoming big sagebrush A. t. var. wyomingensis 10-70 (40**) [103,109]
coastal sagebrush A. californica
desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 
plains grasslands Bouteloua spp.
blue grama-needle-and-thread grass-western wheatgrass B. gracilis-Hesperostipa comata-Pascopyrum smithii
blue grama-buffalo grass B. g.-Buchloe dactyloides
grama-galleta steppe B. g.-Pleuraphis jamesii
blue grama-tobosa prairie B. g.-P. mutica
cheatgrass Bromus tectorum
California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [72]
sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica 105]
paloverde-cactus shrub Cercidium microphyllum/Opuntia spp. 72]
curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1000 [6,85]
mountain-mahogany-Gambel oak scrub C. l.-Quercus gambelii
blackbrush Coleogyne ramosissima
Arizona cypress Cupressus arizonica
northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [72]
beech-sugar maple Fagus spp.-Acer saccharum > 1000 [105]
California steppe Festuca-Danthonia spp. 72]
black ash Fraxinus nigra 105]
juniper-oak savanna Juniperus ashei-Quercus virginiana
Ashe juniper J. a.
western juniper J. occidentalis 20-70 
Rocky Mountain juniper J. scopulorum
tamarack Larix laricina 35-200 [72]
western larch L. occidentalis 25-100 [3]
creosotebush Larrea tridentata
Ceniza shrub L. t.-Leucophyllum frutescens-Prosopis glandulosa 72]
yellow-poplar Liriodendron tulipifera 105]
wheatgrass plains grasslands Pascopyrum smithii 72]
Great Lakes spruce-fir Picea-Abies spp. 35 to > 200 
northeastern spruce-fir Picea-Abies spp. 35-200 [30]
Engelmann spruce-subalpine fir P. engelmannii-A. lasiocarpa 35 to > 200 [3]
black spruce P. mariana 35-200 [30]
blue spruce* P. pungens 35-200 [3]
red spruce* P. rubens 35-200 [30]
pine-cypress forest Pinus-Cupressus spp. 3]
pinyon-juniper Pinus-Juniperus spp. 72]
whitebark pine* P. albicaulis 50-200 [3]
jack pine P. banksiana 30]
Mexican pinyon P. cembroides 20-70 [68,93]
Rocky Mountain lodgepole pine* P. contorta var. latifolia 25-300+ [2,3,83]
Sierra lodgepole pine* P. c. var. murrayana 35-200 [3]
shortleaf pine P. echinata 2-15
shortleaf pine-oak P. e.-Quercus spp. 105]
Colorado pinyon P. edulis 10-49 [72]
slash pine P. elliottii 3-8 [105]
Jeffrey pine P. jeffreyi 5-30 
western white pine* P. monticola 50-200 
Pacific ponderosa pine* P. ponderosa var. ponderosa 1-47 [3]
interior ponderosa pine* P. p. var. scopulorum 2-30 [3,8,61]
Arizona pine P. p. var. arizonica 2-15 [8,16,86]
Table Mountain pine P. pungens 105]
red pine (Great Lakes region) P. resinosa 10-200 (10**) [30,33]
red-white-jack pine* P. r.-P. strobus-P. banksiana 10-300 [30,40]
pitch pine P. rigida 6-25 [12,41]
pocosin P. serotina 3-8 
eastern white pine P. strobus 35-200 
eastern white pine-eastern hemlock P. s.-Tsuga canadensis 35-200 
eastern white pine-northern red oak-red maple P. s.-Quercus rubra-Acer rubrum 35-200 
loblolly pine P. taeda 3-8 
Virginia pine P. virginiana 10 to
sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana 105]
galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea
eastern cottonwood Populus deltoides 72]
aspen-birch P. tremuloides-Betula papyrifera 35-200 [30,105]
quaking aspen (west of the Great Plains) P. t. 7-120 [3,38,65]
mesquite Prosopis glandulosa 64,72]
black cherry-sugar maple Prunus serotina-Acer saccharum > 1000 [105]
mountain grasslands Pseudoroegneria spicata 3-40 (10**) [2,3]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [3,4,5]
coastal Douglas-fir* P. m. var. menziesii 40-240 [3,69,82]
California mixed evergreen P. m. var. m.-Lithocarpus densiflorus-Arbutus menziesii
California oakwoods Quercus spp. 3]
oak-hickory Q.-Carya spp. 105]
oak-juniper woodland (Southwest) Q.-Juniperus spp. 72]
northeastern oak-pine Q.-Pinus spp. 10 to 105]
coast live oak Q. agrifolia 3]
white oak-black oak-northern red oak Q. alba-Q. velutina-Q. rubra 105]
canyon live oak Q. chrysolepis
blue oak-foothills pine Q. douglasii-Pinus sabiniana 3]
northern pin oak Q. ellipsoidalis 105]
Oregon white oak Q. garryana 3]
bear oak Q. ilicifolia 105]
California black oak Q. kelloggii 5-30 [72
bur oak Q. macrocarpa 105]
oak savanna Q. m./Andropogon gerardii-Schizachyrium scoparium 2-14 [72,105]
chestnut oak Q. prinus 3-8
northern red oak Q. rubra 10 to
post oak-blackjack oak Q. stellata-Q. marilandica
black oak Q velutina
live oak Q virginiana 10 to105]
interior live oak Q. wislizenii 3]
blackland prairie Schizachyrium scoparium-Nassella leucotricha
little bluestem-grama prairie S. s.-Bouteloua spp. 72]
redwood Sequoia sempervirens 5-200 [3,32,92]
pondcypress Taxodium distichum var. nutans 70]
western redcedar-western hemlock Thuja plicata-Tsuga heterophylla > 200 [3]
eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis > 200 [105]
western hemlock-Sitka spruce T. heterophylla-Picea sitchensis > 200 
mountain hemlock* T. mertensiana 35 to > 200 [3]
elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. 30,105]
*fire return interval varies widely; trends in variation are noted in the species summary


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Successional Status

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More info for the terms: cover, density, litter, nonnative species, presence, shrubs

Houndstongue is an opportunistic species that exploits conditions suitable for its establishment and growth. In the variable environment of dune habitats, houndstongue populations are usually in decline, and only in rare years are conditions favorable for growth and/or seed production. For this reason, one may see large fluctuations in population density in a single locality [24]. As is typical of biennials, large population increases are observed following reproductive success and large decreases or even local extinctions following reproductive failure. Annual disturbances as well as absence of disturbance can be fatal for biennial plant development; therefore most habitats are only temporarily suitable for biennials. Grazed range provides an environment where gaps are repeatedly created and therefore suitable sites for establishment are usually available [101]. Where it has established on disturbed sites such as roads and around old buildings, it may persist indefinitely, as is evidenced by its continued presence in abandoned mining towns in southwestern Montana, even after 45 to 77 years of recovery [52].

Houndstongue is shade tolerant [98] but grows best in full sunlight, if sufficient water and nutrients are available. In sand dunes it may occur in both open and shaded sites (5-10% of full daylight). Its establishment in open sites may depend on spring and summer rainfall. In half-open habitats, at the edges of the canopies of shrubs or trees, plants are less susceptible to drought [26]. Houndstongue was significantly (p<0.05) positively associated with closed canopies at Mammoth campground in Yellowstone National Park. Here it was more consistently found under high canopy cover than any other nonnative species. Similarly, Lacey and Lacey [59] describe occurrences of houndstongue in areas of thick litter accumulation (as might be found under a forest with high canopy cover) [1].


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Regeneration Processes

More info for the terms: autogamy, competition, cover, perfect, presence, shrubs, vernalization

Houndstongue is a biennial or short-lived perennial that reproduces only by seed. An annual life cycle apparently does not occur anywhere in the entire range of the species [26]. The following discussion of the regeneration processes in houndstongue derives primarily from research in British and Dutch coastal dune areas. More research is needed on houndstongue regeneration on sites where it is invasive in North America.

Breeding system: A review by Upadhyaya and others [99] suggests that houndstongue flowers are perfect (having both male and female parts), and that seed production occurs via autogamy. However, de Jong and others [26] report that houndstongue plants produce only very few nutlets if pollinators are excluded, and that bagging inflorescences in the field generally results in reduced seed set per flower. This suggests some mechanism that prevents self-pollination within the flower. Seed set per flower is greatly increased by exchanging pollen between flowers on the same plant.

Pollination: Houndstongue is pollinated by bumblebees [75]. Flowers are also visited by other bees, thrips, and butterflies [26].

Seed production: Estimates of total seed number per plant in houndstongue range from 50 to more than 2,000 [99]. In Montana, houndstongue seed production ranges from 300-675 seeds per plant [50].

Houndstongue plants typically have 1 or 2 stems, although up to 8 stems per plant have been reported on plants growing in dune grasslands in England. In this ecosystem, a single stem could produce around 300 seeds, and seed number per stem was correlated with stem basal diameter (r=0.84, p<0.01) [11]. In a sand dune area in the Netherlands, larger plants produce more seed per flower, and smaller plants produce more flowers per plant [51]. Researchers there found that watering houndstongue plants had a positive effect on seed set [26].

Each flower has the potential to produce 4 nutlets. A review by Upadhyaya and others [99] reports an average 2.75 nutlets per flower. In Dutch sand dunes, 5.2 to 7.8% of the nutlets produced in a population formed seedlings in the following spring [26]. Boorman and Fuller [11] estimated this figure at 25% on coastal dunes in England.

Seed dispersal: Houndstongue seeds are covered in a spiny husk and possess a protruding barb that enables the seed to adhere to wild and domestic animals thus promoting long-distance dispersal [50]. European studies, however, suggest that animal dispersal is rare in houndstongue [11,26], and wind is considered to be the primary dispersal mechanism [100]. In one study, the majority of houndstongue seeds (75%) fell into an area of radius 5 inches (12 cm) around the parent plant. The greatest recorded dispersal distance was 4.6 feet (1.4 m). With such limited primary dispersal range, even rare dispersal events by animals could be important [11].

It has been proposed that the presence of houndstongue around rabbit warrens in European ecosystems is the result of rabbits cleaning seeds off their fur before entering the warrens. However, seeds do not adhere well to fine rabbit fur [11]. Evidence from a study in British Columbia indicates that cattle are important dispersers of houndstongue seed, picking up about 65% of seeds per stalk in grazed paddocks [23]. Some houndstongue seeds remain on plants well into the winter [11,23,26]. These seeds are dispersed slowly over time by attaching to animal wool and hair. Dispersal via streams and irrigation ditches is unlikely due to the high specific gravity of houndstongue seeds [99]. Although seed dispersal occurs slowly over time, colonization of disturbed sites can take place very quickly [50].

Seed banking: A review by Upadhyaya and others [99] cites several studies that indicate that houndstongue does not produce a large, persistent bank of buried seeds, and that seeds remain viable no longer than 2-3 years. Newly ripened seeds of houndstongue exhibit an innate dormancy [26,99]. Most seeds fall from the plant soon after ripening; however, some seeds remain on plants for up to 2 years, especially in sheltered habitats (e.g. scrub), thus creating an above-ground seed bank. A fraction (less than 5 to 10% in exposed habitats) of seeds that fall to the ground do not germinate in the 1st year [11,100]. A small percentage of these seeds (4-7 %) may remain viable after 1 year [26]. In the Netherlands, viable seeds were found to occur almost entirely within the top 0.4 inch (1 cm) of soil, and viable seeds did not occur deeper than 2 inches (5 cm). Experimentally, all buried seeds had germinated within 9 months at both 0.8-inch (2 cm) and 6-inch (15 cm) depths [100].

Germination: Seed burial depth, ambient temperature, moisture, soil nitrate levels, and light have been shown to affect seed germination in houndstongue (reviews by [26,99]).

The viability of freshly harvested houndstongue seeds exceeds 90%, although newly ripened seeds of houndstongue exhibit an innate dormancy [26,99]. Thus, houndstongue seeds remain ungerminated throughout the fall and winter and germinate uniformly in the spring, suggesting a vernalization requirement for dormancy release. In Dutch coastal dunes, almost all houndstongue seedlings emerge in March and April, the main germination period being March, with very little to no germination in any other month [11,100].

Germination in houndstongue generally requires some form of scarification or softening of the seed coat. Seeds are likely to remain dormant until they can take up sufficient water [11]. Nitrate also breaks seed dormancy [11,100]. In laboratory studies, germination rate was highest after 6-12 weeks of moist-chilling at 32 to 50 degrees Fahrenheit (0-10 ºC). Germination of dispersed seeds depends strongly on burial. Of the viable houndstongue seeds buried 0.4 inch (1 cm) in sand, almost 100% germinated before and during the 1st spring, while germination on the surface was less than 4% [26,100]. Darkness may either stimulate or have no effect on germination of houndstongue seeds [100].

Seedling establishment/growth: Large temporal and spatial variation in the number of surviving seedlings per reproductive individual has been observed for houndstongue [24]. It is estimated that less than 1% of dispersed seed survives to produce more seed (review by [26]). Reports of 7 to 40% of dispersed houndstongue seeds were retrieved as seedlings in spring. The remaining seeds may have been dispersed secondarily or lost through predation, although death of seeds or seedlings immediately after germination was the most plausible explanation [24,75]. First year survival of seedlings from spring to fall ranged from 22 to over 50% on Dutch coastal dunes [24].

Houndstongue seedlings have a low growth rate and are not strongly competitive. Plants do well when their competitors are kept in check (e.g. grazed by rabbits) [11]. Small-scale disturbances are important for houndstongue establishment. Houndstongue occurs only in areas of the Dutch coastal dunes where grazing by horses and cows is allowed [20]. Prins and Nell [74] compared population dynamics of houndstongue with and without protection from generalist herbivores (insects, rabbits and mice). Houndstongue mortality was significantly higher in protected populations for 3 consecutive years (p<0.05). Germination, seedling establishment and number of flowering plants were also lower inside exclosures. Similar results were observed in exclosure studies in northeastern Oregon, where percent canopy cover of houndstongue increased over a 30 year period under grazing pressure from both cattle and wildlife [81]. Generalist herbivores seem to play a positive role in the population dynamics of houndstongue by reducing competition from grasses [74]. Seedling growth and survival are also reduced by intraspecific competition at high population densities [26].

Seeds of houndstongue have large nutrient reserves that allow rapid seedling root growth so that plants can be well established before drier weather begins (reviews by [26,99]). Most seedling mortality, however, is attributed to water deficit in the early summer months, before the development of a deep and extensive root system [11,20]. Seedling survival is lowest in dry summers and on exposed sites [24]. Seedling mortality was negatively correlated with the water content in the top 4 inches (10 cm) of soil (r=-0.65, p<0.001) in Dutch coastal dunes. Early seedling mortality (April to May) was also negatively correlated with the cover of shrubs and trees (r=-0.70, p<0.001) and soil humus content, (r=-0.63, p<0.01). Variation in rainfall may cause yearly differences in houndstongue survival and growth, and also affects its distribution over shaded and exposed habitats on dune sites [25]. A large proportion of houndstongue rosettes that delayed reproduction buffered the population against low seedling recruitment in some years (a bud bank versus a seed bank) [24].

Asexual regeneration: Houndstongue reproduces only by seed.


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Growth Form (according to Raunkiær Life-form classification)

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Life Form

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Life History and Behavior



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More info for the terms: monocarpic, natural, vernalization

Houndstongue seeds overwinter predominantly in the top (1 cm) of soil, although some seeds may remain attached to the parent plant throughout the winter [99]. Houndstongue germination starts in late winter and early spring, when soil temperature rises above the freezing point. Houndstongue plants then develop from seedling to rosette within the 1st year of growth. When night frosts begin in autumn, rosette leaves die back and the taproot remains. Houndstongue requires a vernalization period before stem elongation can occur. Stem elongation is probably stimulated by day length [26]. Flowering is strongly size-dependent, with the probability of flowering increasing with the size of the plant. There may also be a critical size below which plants do not flower [27]. The main period of flowering is about 55 days, with seed ripening requiring an additional 70 days. Most ripened seeds fall to the ground within 4 months of ripening [99].

Typical flowering dates are reported by area as follows:

Area Flowering dates Reference
Carolinas May-July [76]
Great Plains May to July [37]
IL May-July [67]
Intermountain West May to July [17]
IA May-June [54]
MT mid-June [50]
NM May-August [63]
BC May-July [98]

Although usually a biennial, houndstongue can behave as a short-lived perennial. Under fertile conditions plants typically flower in their 2nd year. Under adverse environmental conditions, flowering can be delayed until the plants reach a sufficient size for vernalization [26]. Delay of flowering is common in natural populations of houndstongue on Dutch coastal dunes. Over a 7-year period, the percentage of rosettes that flowered ranged from 2 to 25%. The proportion of rosettes flowering was positively correlated (r=0.62, p=0.05) with rainfall in the previous year and was reduced after a very cold winter [27].

While most houndstongue plants die after flowering, houndstongue is not strictly monocarpic. Of 55 houndstongue plants studied, 7 flowered again in both the 2nd and 3rd years and 2 in their 3rd and 4th years [11]. Repeated flowering has also been observed in houndstongue not only after damage to the flowering plant, but also in undamaged plants under both natural and garden conditions [26].


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Molecular Biology and Genetics

Molecular Biology

Barcode data: Cynoglossum officinale

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)


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Statistics of barcoding coverage: Cynoglossum officinale

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 8
Specimens with Barcodes: 9
Species With Barcodes: 1
Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)


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Conservation Status

National NatureServe Conservation Status


Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe


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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

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At the time of this writing (2002), houndstongue is classified as a noxious, restricted or prohibited weed or weed seed in 6 states in the United States and 2 Canadian provinces [97]. See the Invaders or Plants databases for more information.


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Impacts and Control

More info for the terms: competition, cover, density, fire management, frequency, fresh, invasive species, litter, natural, restoration, root crown, succession

Impacts: Houndstongue can establish rapidly and form dense monocultures in disturbed habitats. Populations of houndstongue displace native plant species and hinder the re-establishment of valuable range species, thereby decreasing availability of forage to wildlife and livestock [80]. It is most detrimental on rangelands and hayfields because of its toxicity to livestock, although, in most cases, the fresh plant is considered unpalatable by livestock and is generally avoided (see Importance to Livestock and Wildlife) [50,99].

The barbed seeds of houndstongue readily attach to wool and fur. This can create marketing problems and require extra time and money for removal, thus reducing the value of livestock. The seeds can also attach to the eyelashes of animals and cause eye damage, and the foliage may cause dermatitis [50,99].

Control: Houndstongue can be controlled by killing plants and/or preventing seed production. Long-term control of houndstongue requires an integrated management approach [50].

Prevention: Prevention is the most effective method for managing invasive species, including houndstongue [50,88]. Preventing or dramatically reducing seed production and dispersal, detecting and eradicating weed introductions early, containing current infestations, minimizing soil disturbances, establishing competitive grasses, and managing grazing properly will all help decrease the spread of infestations.

Cleaning livestock when they are moved from an infested area to an uninfested area is critical to prevent seed spread [23]. Houndstongue seeds also readily adhere to shoes and clothing and need to be removed and carefully disposed of (burned or bagged). It is important to clean mowers, vehicles, and tillage equipment after operating in an infested area. When seeding is necessary, use clean, certified weed-free seed and mulch to ensure that these or other weeds are not being sown.

Place a priority on controlling small infestations so they do not expand. Conducting aggressive monitoring and treatment several times each year can help with early detection and containment of infestations when they are small. Monitoring efforts are best concentrated on the most disturbed areas in a site, particularly along roadsides, parking lots, fencelines, and waterways. When an infestation is found, the location can be recorded and the surrounding area surveyed to determine the size and extent of the infestation, so these sites can be revisited on follow-up surveys. For more on monitoring see Johnson [47].

Historic overgrazing by livestock and native ungulates encourages invasion by houndstongue [80]. In areas susceptible to invasion, proper livestock grazing should include altering timing, frequency and level of defoliation to allow a full recovery of desirable grass species. This grazing regime promotes litter accumulation to allow proper nutrient cycling and enhances vigor of desirable grasses which limits invasion by rangeland weeds [50]. For more information on grazing management for weed control see Olson [71].

Weed prevention and control can be incorporated into all types of management plans, including logging and site preparation, management of grazing allotments, recreation management, research projects, road building and maintenance, and fire management. See the "Guide to noxious weed prevention practices" [95] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

Integrated management: The goal of any management plan should be to not only control invasive plants, but also to improve the affected community by maximizing forage quality and quantity and/or preserving ecosystem integrity, and preventing reinvasion or invasion by other invasive species. This must be done in a way that is complementary to the ecology and economics of the site [28,45]. Effective long-term control requires that invasive plants be removed and replaced by more desirable and weed-resistant plant communities [45]. Once the desired plant community has been determined, an integrated weed management strategy can be developed to direct succession toward that plant community by identifying key mechanisms and processes directing plant community dynamics (site availability, species availability, and species performance) and predicting plant community response to control measures [87]. This requires a long-term integrated management plan.

Most often, a single method is not effective for controlling an invasive plant, but there are many possible combinations of methods that can achieve the desired objectives. Methods selected for removal or control of houndstongue on a specific site will be determined by land use objectives, desired plant community, extent and nature of the infestation(s), environmental factors (nontarget vegetation, soil types, climatic conditions, important water resources), economics, and effectiveness and limitations of available control techniques [78].

Managers are encouraged to use combinations of control techniques in a manner that is appropriate to the site objectives, desired plant community, available resources, and timing of application. For information on integrated weed management without herbicides, see the Bio-Integral Resource Center (BIRC) website.

Physical/mechanical: Tillage, hoeing, and hand-pulling may provide effective control of houndstongue, providing these operations are done before the reproductive growth stages to prevent seed production. Mechanical methods may not be practical on rangeland and natural areas, but could be useful in improved pastures or roadsides.

First-year houndstongue plants are difficult to control by aboveground cutting, as the prostrate rosette resists mowing and grazing [99], and nutrient reserves of the taproot acquired during the 1st year are sufficient for normal seed production the following year, even if the plants are completely defoliated early in the spring [11,98]. Furthermore, defoliation at the rosette stage may cause the plant to delay flowering for a year and thus result in a larger plant with a greater seed output [102]. Mowing or clipping 2nd year plants can reduce seed production in houndstongue provided that it is done before seeds are formed and that defoliation is severe enough to prevent regrowth and subsequent flowering [80]. Clipping 2nd year houndstongue plants 0 to 3 inches (0-7 cm) above ground in late June reduced but did not eliminate seed production in houndstongue (Dickerson and Fay 1982, as cited by [26,98]). Sixty percent of cut plants failed to regrow, and seed production of the plants that resumed growth declined to about 25 seeds per plant compared to 364 seeds per plant in the unclipped controls. Boorman and Fuller [11], on the other hand, found that removing the leaves from 2nd year plants had little effect on seed number or seed weight. Additionally, if the flowering stalk is cut off or if flower buds are removed, axillary buds lower on the stem may be activated and develop into cymes; or the plant may respond by forming vegetative side-rosettes from the axils of old leaf-bases [26]. Response of houndstongue after serious defoliation depends on the vigor of plants and the fertility of the site, especially nitrogen availability. Plants with low growth rates respond quite poorly to defoliation, while vigorous plants may recover and set seed [102].

Plowing is said to control houndstongue [99]. However, tillage is not usually appropriate in wildlands and rangelands since it can damage important desirable species, increase erosion, alter soil structure, and expose the soil for rapid reinfestation by houndstongue and other invasive species [62]. Cutting the root crown of either young rosettes or older houndstongue plants (before seed set) 1 to 2 inches (2.5-5 cm) below the soil surface in autumn or early spring and removing top-growth can be effective in controlling small infestations [50,99]. Hand-pulling of houndstongue on the Dunstan Homestead in northeastern Oregon reduced houndstongue populations by 85% [80]. For very large infestations, it may be difficult to get enough labor for cutting or hand-pulling. The Salmon River Restoration Council (SRRC) provides an example of watershed-scale weed control using primarily mechanical control methods and volunteer labor.

Fire: See Fire Management Considerations.

Biological: Biological control of invasive species has a long history; many important considerations need to be made before implementation of a biological control program. The reader is referred to other sources [78,108] and the Weed Control Methods Handbook [94] for background information on biological control. Additionally, Cornell University and NAPIS websites offer information on biological control.

As of 1999, 5 biological control agents were being screened for their potential use on houndstongue. These include a root weevil (Mogulones cruciger), a seed weevil (M. borreginis), a stem weevil (M. trisignatus), a root beetle (Longitarsus quadriguttatus), and a root fly (Cheilosia pasquorum) [50]. Recent research on the host specificity of Mogulones cruciger indicates that this agent can complete full development on several plant species within closely related genera in the Boraginaceae, but prefers houndstongue as a host. This is a matter of concern since at least one species in the genus Cryptantha (C. crassipes) is listed as endangered in the U.S., and 6 of the 12 Cryptantha species tested supported full development of the root weevil (C. crassipes was not tested) [22]. As of the time of this writing, no further information is available regarding the status of the other biocontrol agents. Erysiphe cynoglossi is a commonly encountered pathogen on houndstongue in western North America that is being studied for its impact on vegetative plant growth and reproduction [21].

Chemical: Herbicides are effective in gaining initial control of a new invasion or a severe infestation, but are rarely a complete or long-term solution to weed management [15]. Herbicides are more effective on large infestations when incorporated into long-term management plans that include replacement of weeds with desirable species, careful land use management, and prevention of new infestations. Control with herbicides is temporary, as it does not change those conditions that allow infestations to occur [110]. See the Weed Control Methods Handbook for considerations on the use of herbicides in natural areas and detailed information on specific chemicals.

Picloram, dicamba, chlorsulfuron, metsulfuron and 2,4-D amine can kill houndstongue plants. Repeated applications may be necessary for several years to maintain adequate control [50,59,99]. Herbicide choice and rates are influenced by growth stage, stand density, and environmental conditions (e.g. drought or cold temperatures). Check with state or county weed specialists for appropriate local use rates and timing.

Cultural: No matter what method is used to kill weeds, re-establishment of competitive, desirable plant cover is imperative for long-term control. Fertilization and reseeding with competitive, adapted species is often necessary in areas without a residual understory of desirable plants [78].

Houndstongue seedlings have a comparatively low growth rate and are not strongly competitive. Interspecific competition severely reduces the dry weight of 1st and 2nd year houndstongue plants [99]. Generalist herbivores play a positive role in the population dynamics of houndstongue by reducing competition from grasses in coastal dunes in the Netherlands [20,74]. Similarly, in exclosure studies in northeastern Oregon, percent canopy cover houndstongue increased over a 30-year period under grazing pressure from both cattle and wildlife [81]. These studies suggest, therefore, that planting and maintaining competitive species can effectively control houndstongue, although more research is needed.


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Relevance to Humans and Ecosystems


Importance to Livestock and Wildlife

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Houndstongue causes poisoning in horses and cattle [9,14,48,53,90]. Houndstongue contains various pyrrolizidine alkaloids (PAs), whose concentrations are highest during its rosette stage and decrease as the plant matures [9,53]. PAs are known to cause liver damage or failure in livestock [90]. Kedzie-Webb and Sheley [50] suggest that PAs are toxic to horses and cattle but not to domestic sheep. Poisoning can occur when houndstongue is cut and dried with harvested hay, or when animals are confined to a small area lacking desirable forage. Most livestock poisonings occur from ingestion of contaminated hay or feed [90]. The acute or chronic nature of poisoning depends on the PA concentration, amount eaten, and rate of ingestion [9,50]. Any level of houndstongue contamination in feed should be considered potentially lethal for all livestock [90].

Kufeld and others [57] report light use of houndstongue by Rocky Mountain mule deer in winter in Montana. Domestic sheep commonly graze houndstongue leaves [26]. There are few direct effects of herbivores on houndstongue where it occurs on coastal dunes in England and the Netherlands. It is not normally eaten by rabbits [11], although rabbits have been observed digging up taproots in winter [26]. A 3-year study by Prins and Nell [74] indicates only low levels of leaf herbivory on houndstongue in coastal dunes in the Netherlands. Rabbits caused some leaf damage in early spring, and no root consumption by rabbits was found. From June to November, larvae of the oligophagous Lepidopteran, Ethmia bipunctella, are the most important herbivores on houndstongue. Captive mice eat nutlets, but it is unknown whether this occurs in the field. Ring-necked pheasants graze on the cotyledons and on whole seedlings of houndstongue (review by [26]).

Palatability/nutritional value: Green houndstongue plants have a distinctive odor that discourages animals from eating it, but when dried it becomes more palatable [9,53].

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Other uses and values

A review by Upadhyaya and others [99] suggests the following traditional uses of plants in the borage family such as houndstongue. Extracts of Boraginaceous roots have been used for centuries as "folk" remedies for a variety of disorders such as eczema, fever, acne, corn callus, dermatophytosis, burns and hemorrhoids. Lipophilic red pigments associated with the outer surface of the roots of many members of the Boraginaceae are antibacterial, antitumorogenic and possess wound-healing activity. These pigments have also been used as food and wine colorants in at least 12 European countries. Roots and leaves of houndstongue have been used as "folk" pesticides; their herbage has been reported to repel moles in gardens and to protect stored fruits and vegetables from rodents.


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Cynoglossum officinale

Flowers and leaves

Cynoglossum officinale[1][2] (houndstongue, houndstooth, dog's tongue, gypsy flower, and rats and mice due to its smell) is a herbaceous plant of the family Boraginaceae, found in most parts of Europe, and also North America where it was accidentally introduced.[3]


It can be either annual or biennial, with reddish-purple flowers blooming between May and September. It lives in wet places, waste land and hedges.


The name houndstongue comes from the belief that it could ward off dog attacks if a leaf was worn in the shoe.[citation needed]


Herbalists use the plant as a treatment for piles, lung diseases and persistent coughs.[4] Houndstongue ointment is said to cure baldness and be used for sores and ulcers.[4] These uses are not supported by scientific evidence.[4]

In 1725, houndstooth was presented in the family dictionary, Dictionaire oeconomique, as part of a cure for madness.[5] In that book, madness was viewed as "a distemper, not only of the understanding, but also of the reason and memory, proceeding from a cold, which drys up everything it meets with that is humid in the brain."[5] To cure madness, Dictionaire oeconomique noted:

You must shave the head of the unhappy patient, and after that, apply to it a pidgeon, or a hen quite alive; or else bathe it with some brandy distilled with rosemary, elder, hounds tooth, and the roots of bugloss[disambiguation needed], or with the oyl of elder flowers: they rub their heads and wash their feet with a decoction of the flowers of camomile, melilot, balm gentle and laurel; they put into their noses the juice of comfrey, with either two or three spoonfuls of honey-water, broth, or white-wine, wherein wormwood[disambiguation needed] and sage are infus'd ; or else they do for five and twenty days together, mix with their broth in the morning, halt a dram of the allies of tortoise, and they put into the pot bugloss, borage, with a pinch of rosemary to season it.[5]

In the 1830s, houndstooth was known in France to be made into an emollient and diuretic for daily use in inflammatory diseases, especially of the urinary organs.[6] To prepare as a diuretic, the houndstooth leaves were mashed, and then boiled in water to extract oils, volatile organic compounds, and other chemical substances.[6] The mix could be sweetened with liquoriee to create Ptisan of Dog's-grass.[6] After decoction, the herbal tea was taken internally a cupful at a time.[6] In 1834, the Hospital of Paris provided a formula of 2/3 ss—J to Oij of water for houndstooth tea.[6] By the end of the 1830s, doctors in England were using houndstooth as an antiaphrodisiac to combat venereal excesses.[7]

In 1891, the U.S. state of Michigan identified hounds tooth, along with flea-bane, rag weed, burdock, cockle-bur, and stickseed, as some of the worst weeds in the state.[8]


Cynoglossum officinale contains tumorigenic pyrrolizidine alkaloids.[9]


  1. ^ "Cynoglossum officinale". Integrated Taxonomic Information System. 
  2. ^ Cynoglossum officinale at USDA PLANTS Database
  3. ^ "Invasive Species: Houndstongue". United States National Agricultural Library. 
  4. ^ a b c Howard, Michael. Traditional Folk Remedies (Century, 1987); p.161
  5. ^ a b c Chomel, Noel; Richard Bradley (1725). Dictionaire oeconomique: or, The family dictionary. Printed for D. Midwinter. Retrieved October 8, 2011. 
  6. ^ a b c d e Ryan, Michael (1835). "Collection of Formula of the Civil and Military Hospitals of France, Germany, Italy, Great Britain and Ireland". London Medical and Surgical Journal (G. Henderson) 7: 527. OCLC 13350693. Retrieved October 8, 2011. 
  7. ^ Ryan, Michael (1839). Prostitution in London, with a comparative view of that of Paris and New York, with an account of the nature and treatment of the various diseases, caused by the abuses of the reproductive function. H. Bailliere. p. 385. Retrieved October 8, 2011. 
  8. ^ Michigan Dairymen's Association (1891). Seventh Annual Report of the Secretary of the Michigan Dairymen's Association. Robert Smith & Co. p. 23. Retrieved October 8, 2011. 
  9. ^ Fu, P.P., Yang, Y.C., Xia, Q., Chou, M.C., Cui, Y.Y., Lin G., "Pyrrolizidine alkaloids-tumorigenic components in Chinese herbal medicines and dietary supplements", Journal of Food and Drug Analysis, Vol. 10, No. 4, 2002, pp. 198-211 [1]


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Names and Taxonomy


The currently accepted scientific name for houndstongue is Cynoglossum officinale L.
(Boraginaceae) [17,35,37,42,43,63,76,104,107]. Hybridization of houndstongue has been reported in Europe
[26], but not in North America [99].


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Common Names




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