White Bursage

Shrubs, 10–40(–60+) cm. Stems erect. Leaves mostly alternate; petioles 2–8(–12+) mm; blades (white) ovate to elliptic, 10–25(–45) × 8–15(–30) mm, (1–)2–3-pinnately lobed, abaxial and adaxial faces densely strigillose. Pistillate heads intermixed with staminates (sometimes wanting or staminates sometimes wanting, plants unisexual); florets (1–)2. Staminate heads: peduncles 0–1(–2) mm; involucres shallowly cup-shaped, 3–5 mm diam., ± strigillose; florets 8–15+. Burs: bodies ± globose, 3–5+ mm, pilosulous and/or gland-dotted, spines 12–25+, scattered, ± subulate (± navicular at bases), 2–4 mm, tips straight. 2n = 36, 72, 108, 126.

Franseria dumosa A. Gray in J. C. Frémont, Rep. Exped. Rocky Mts., 316. 1845

More info for the term: shrub

burrobush
bursage
burroweed
white bursage

TAXONOMY:
The scientific name for burrobush is Ambrosia dumosa (Gray) Payne [35].
It is a member of the aster family (Asteraceae). There are no recognized
infrataxa.


LIFE FORM:
Shrub

FEDERAL LEGAL STATUS:
No special status

OTHER STATUS:
NO-ENTRY




DISTRIBUTION AND OCCURRENCE
SPECIES: Ambrosia dumosa
GENERAL DISTRIBUTION:
Burrobush occurs throughout the Sonoran and Mojave deserts although
it is typically considered a Mojave Desert species [1].  It ranges north
to Death Valley, California, southern Nevada, and southwestern Utah.  It
extends along the Gulf in Baja California as far south as Bajia Los
Angeles and into Sonora as far south as Tiburon Island [41].

Burrobush occurs throughout the Sonoran and Mojave deserts although
it is typically considered a Mojave Desert species [1].  It ranges north
to Death Valley, California, southern Nevada, and southwestern Utah.  It
extends along the Gulf in Baja California as far south as Bajia Los
Angeles and into Sonora as far south as Tiburon Island [41].



Distribution of burrobush in the United States. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, June 28] [48].

More info for the term: fuel

Biomass production and thus fuel loadings vary seasonally and annually
for burrobush.  In 1971 and 1974 in Rock Valley, Nevada, estimated
abovegound stem dry mass of burrobush was 31 and 41 grams per square
meter, respectively.  Net aboveground production was consistently higher
in spring than in fall.  In 1973, after an above average year of
rainfall, flowers and fruits made up almost half of the new tissue
produced by burrobush [47].

More info for the terms: association, codominant, cover, density, natural, tree

Burrobush is a dominant or codominant member of most plant
communities in the Sonoran and Mojave deserts.  It usually occurs in
open, species-poor communities with creosote bush (Larrea tridentata).

At the northern boundary of burrobush, in the transition zone
between the Mojave and Great Basin deserts, associated species of the
creosote bush-burrobush community include wolfberry (Lycium spp.),
range ratany (Krameria parvifolia), Mojave yucca (Yucca schidigera),
California jointfir (Ephedra funera), spiny hopsage (Grayia spinosa),
and winterfat (Krascheninnikovia lanata) [38,47].  The density of white
bursage is about 2,500 plants per hectare [3,47].

Approximately 70 percent of the Mojave Desert is covered with open or
very open stands of creosote bush and burrobush [15,29,40].
Associated species in the Mojave Desert include desertsenna (Cassia
armata), Nevada ephedra (Ephedra nevadensis), white burrobrush
(Hymenoclea salsola), and wolfberry [22].

In the Sonoran Desert, associated members of the creosote bush-white
bursage community are acacia (Acacia paucipina), fourwing saltbush
(Atriplex canescens), ocotillo (Fouquieria splendens), big galleta
(Hilaria rigida), cholla (Opuntia spp.) and western honey mesquite
(Prosopis glandulosa var. torreyana) [40].  In the Arizona Upland
Subdivision of the Sonoran Desert, the density of burrobush is 549.7
plants per hectare and burrobush cover is 2.7 percent.  In the Lower
Colorado River Valley, the density of burrobush is 84 plants per
hectare and burrobush cover is 0.1 percent [29].

In addition to the creosote bush-burrobush association, burrobush
is a member of the following associations:  Joshua tree (Yucca
brevifolia)-big galleta [24], saguaro (Carnegiea gigantea)-paloverde
(Cercidium spp.) [39], Sonoran creosote bush scrub, Mojave creosote bush
scrub, and Mojave mixed woody scrub [22].

Publications listing burrobush as a dominant or codominant species
include:

Sonoran Desert [10]
Preliminary descriptions of the terrestrial natural communities of California
  [22]
Vegetation of the Santa Catalina Mountains: community types and
  dynamics [34]
Mojave Desert scrub vegetation [60]

More info for the term: shrub

Shrub

More info for the term: cover

Creosote bush-burrobush communities are poorly suited for livestock
grazing because of low productivity and low water availability [23].

Burrobush is sensitive to browsing.  Browsing significantly
decreased the cover and volume of burrobush by 27 and 21 percent,
respectively, in the Mojave Desert [51].  In the Lower Colorado River
Valley, overbrowsing decreased the cover of burrobush from 2.26 to
0.04 percent [21].

Pollution from electric power generating facilities may also decrease
burrobush.  Burrobush showed intermediate sensitivity to sulphur
dioxide and nitrogen dioxide fumigation [45].

More info on this topic.

Burrobush leafs out in February or March; the mean leafing-out date
in Rock Valley, Nevada, was February 23.  The mean flowering date was
May 2 [46].  Burrobush seeds usually germinate following heavy
September precipitation [6].  A minimum amount of rainfall is required
to induce germination.  For instance, a 1971 rain of 1 to 1.96 inches
(25-49 mm) was sufficient but neither an August 1972 rain of 0.68 inch
(17 mm) nor a July rain of 0.84 inch (21 mm) promoted germination [2].

Burrobush has a drought dormancy period in the summer and may have
an induced dormancy period during the winter if freezing night
temperatures kill its leaves [1].

More info for the terms: fire regime, rhizome, root crown, shrub

   Small shrub, adventitious-bud root crown
   Rhizomatous shrub, rhizome in soil
   Initial-offsite colonizer (off-site, initial community)

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".

The scientific name for burrobush is Ambrosia dumosa (Gray) Payne [35].
It is a member of the aster family (Asteraceae). There are no recognized
infrataxa.

Franseria dumosa A. Gray; Torr. in From. Rep. Calif. 316
1845.
Gaerlneria dumosa Kuntze, Rev. Gen. 339. 1891.
A shrubby perennial, with divaricate subspinose branches, 3-6 dm. high; young branches cinerous, strigose; leaves 1-2 cm. long, ovate in outline, pinnately or bipinnately divided, grayish-strigose on both sides, both primary and secondary divisions obovate or elliptic, the latter about 2 mm. wide; inflorescence racemose, the pistillate heads often intermixed with the staminate ones, the latter on short peduncles; involucre about 5 mm. broad, saucer-shaped, canescent; lobes 5-8, oval or ovate; paleae of the receptacle with broad dilated rhombic-spatulate tips, villous; corolla pubescent; anthers acutish; pistillate flowers and fruit similar to those of F. albicaulis, but the spines usually broader, lance-subulate.
Type locality: Sandy uplands of the Mojave River.
Distribution: Mojave Desert, southern California and southern Nevada; near Yuma, Arizona.

Ambrosia dumosa, the burro-weed or white bursage, a North American species of plants in the family Asteraceae. It is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California, Nevada, and Utah and the Sonoran Desert of Arizona and northwestern Mexico (Baja California, Baja California Sur, Sonora, Chihuahua).

Ambrosia dumosa has been studied to determine allelopathic interactions with creosote bush, Larrea tridentata, which produces a chemical that inhibits the growth of A. dumosa. Other studies have suggested that A. dumosa roots produce a chemical that causes them to grow away from conspecific roots, preventing competition for water resources. In addition to burro-weed, A. dumosa is also commonly called white bursage, and burrobush.