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Wildlife, Animals, and Plants
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Introductory
SPECIES: Flourensia cernua | Tarbush
ABBREVIATION :
FLOCER
SYNONYMS :
NO-ENTRY
SCS PLANT CODE :
FLCE
COMMON NAMES :
tarbush
hojase
blackbrush
varnishbush
TAXONOMY :
The currently accepted scientific name for tarbush is Flourensia cernua
DC. It is a member of the Compositae family.
LIFE FORM :
Shrub
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
COMPILED BY AND DATE :
Sara Lynn Korthuis, September 1988
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Korthuis, Sara Lynn. 1988. Flourensia cernua. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Flourensia cernua | Tarbush
GENERAL DISTRIBUTION :
Tarbush is essentially restricted to the Chihuahuan Desert, where it may
be locally or generally abundant [14]. It occurs in Arizona,
California, New Mexico, Texas, and Mexico at elevations ranging from
1,312 feet (400 m) to 6,500 feet (1,981 m) [1,4,12].
ECOSYSTEMS :
FRES30 Desert shrub
FRES33 Southwestern shrubsteppe
FRES40 Desert grasslands
STATES :
AZ CA NM TX MEXICO
ADMINISTRATIVE UNITS :
BIBE CACA FOBO GUMO WHSA
BLM PHYSIOGRAPHIC REGIONS :
7 Lower Basin and Range
12 Colorado Plateau
13 Rocky Mountain Piedmont
KUCHLER PLANT ASSOCIATIONS :
K044 Creosotebush - tarbush
K059 Trans-Pecos shrub savanna
SAF COVER TYPES :
NO-ENTRY
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Tarbush is associated with creosotebush (Larrea tridentata), mesquite
(Prosopis spp.), burrograss (Scleropogon brevifolius), and tobosa
(Hilaria mutica). It readily replaces native grasses in desert
grasslands [1,28,32].
VALUE AND USE
SPECIES: Flourensia cernua | Tarbush
WOOD PRODUCTS VALUE :
NO-ENTRY
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Tarbush is occasionally eaten by jackrabbits and other wildlife. It is
not generally used by livestock unless little else is available [26].
Mature fruit while still on the plant is poisonous to sheep, goats, and
other livestock [9,10,16,26]. Cattle have reportedly died after eating
the flowers and green or mature fruits [5,10]; nonfruiting plants can
apparently be grazed with no ill effect [10]. Tarbush fruit and browse
may also be toxic to wildlife, particularly if forced to feed on it
exclusively.
PALATABILITY :
The peppery, bitter quality of tarbush herbage makes it unpalatable to
livestock and wildlife [15,16,28].
NUTRITIONAL VALUE :
Tarbush forage in an arid New Mexico range showed relatively high
protein, ash, lignin, and ether extract levels. Calcium content was
high and phosphorus levels met the requirements for livestock. However,
goats fed a diet consisting solely of tarbush leaves became severely
emaciated, indicating low nutrient content for this forage in some areas
[10].
COVER VALUE :
Tarbush provides much-needed shade in summer for range animals [16]. It
is used for cover by the western whiptail and side-blotched lizard [23].
VALUE FOR REHABILITATION OF DISTURBED SITES :
NO-ENTRY
OTHER USES AND VALUES :
In northern Mexico, the leaves and flower heads were used historically
to make a decoction for treating indigestion [17,26].
MANAGEMENT CONSIDERATIONS :
Tarbush increases in response to overgrazing. It is considered a weed
in desert rangelands where it is increasing in acreage. Invasion of
grasslands by tarbush and other shrubs decreases their productivity and
value to livestock and wildlife, and promotes wind and sheet erosion and
the formation of arroyos [9,30,31]. Biological control methods have
been considered but as of 1985 no such methods had been implemented
either in the United States or Mexico [9].
Low density stands (less than 80 plants/acre [200 plants/ha]) can be
controlled by individual shrub treatment with herbicides. Aerial
applications of dicambra or tebuthiuron have produced good results.
Picloram and 2,3,6-TBA have proven less effective [11,13].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Flourensia cernua | Tarbush
GENERAL BOTANICAL CHARACTERISTICS :
Tarbush is a much-branched, densely leafy shrub. It grow from less than
1 foot (0.30 m) to 3 to 7 feet (1-2 m) tall. This native perennial
produces a tarlike odor, hence its common name [8,16,26].
Tarbush leaves are alternate, simple, and elliptical, and are covered
with small black glands.. The sticky leaves grow up to 1 incg (2.5 cm)
long. The scaly stem appears white because of hairs and dried resin
[16,20,26].
The composite flower heads are small, solitary, and inconspicuous. The
disked flower heads lack ray flowers and are pendant [8,16,26]. The
fruit is an achene. Densely hairy, relatively motile seeds are produced
in small pendant clusters [2,5].
RAUNKIAER LIFE FORM :
Phanerophyte
Therophyte
REGENERATION PROCESSES :
Tarbush grows at a slow rate and can spread vegetatively. This shrub
produces a relatively motile seed that can be dispersed by wind [5,6].
SITE CHARACTERISTICS :
Tarbush thickets inhabit deserts, and dry soils of valleys, mesas,
flats, and foothills [16,26]. It reaches its best development in heavy
clay loam soils with some gravel near the surface on sites that receive
some flood water. It is often found in limestone or calcareous soils.
Although it grows intermixed with creosotebush, it prefers soils that
are deeper (24 inches [60 cm]) than those in areas where creosotebush
dominates. It also grows into fringe areas of tobosa swales
[5,7,16,20]. Although only 1 foot (0.30 m) tall or less in dry areas,
tarbush may reach heights of 6 feet (1.8 m) or more on favorable sites
[16].
Elevations range from 3,000 to 6,500 feet (1,067-1,981m) [16].
Primarily an inhabitant of the Chihuahuan Desert, tarbush is adapted to
an average annual precipitation of 9.4 inches (24 cm), 70 percent of
which falls in the summer when desert plants tend to be dormant and only
20 percent of which falls in the winter [2]. Temperatures are extreme;
June has an average high of 97 degrees F (36 deg C), January averages a
high of 56 degrees F (13 deg C). Temperatures exceeding 89 degrees F
(32 deg C) can occur on 115 or more days in a year, but temperatures can
also fall below 32 degrees F (0 deg C) on 66 days [2,22].
SUCCESSIONAL STATUS :
Tarbush occurs in the desert shrub ecosystem, a system which may fall
outside traditional ideas of succession. Extreme events or
"disturbances" of the classical deciduous forest model of succession do
not necessarily produces changes in species composition in the desert.
The desert may be "autosuccessional" in this regard. In addition, if
species composition does change, no predictable sequence of successional
events can be made. The concept of climax as the final phase in a
predictable, relatively unidirectional sequence of change in species
composition may not be a valid element of desert succession [32].
Disturbance, even to the point of total destruction of aboveground
vegetation, does not drastically alter soil or water conditions in the
desert. The "climax" or stable vegetation type is well adapted to the
extremes of desert climate whether a site is bare or vegetated, unlike
mesic counterparts. However, if long-term disturbance has led to
species composition change, this may not be reversed by a simple
cessation of disturbance. Reinvasion by species of the original
community may necessitate unusual and extreme conditions. Because the
pace of regrowth is slow in deserts, successional stages may appear to
occur, but these may not be necessary for establishment of the stable
community that will emerge over time [19].
Campbell [6] considered tarbush to be characteristic of the late seral
stage on clay soils and of climax on gravelly clay loams in southern New
Mexico. Muller [21] stated that no seral stages occurred in
creosotebush-tarbush climax types since disturbance did not result in
invasion of new species. Such communities did not develop along
classical successional lines.
Tarbush is part of the desert grassland disclimax in which shrubs invade
the herbaceous community following grazing. Tarbush primarily invades
tobosa grasslands. Quickly reinvading, this shrub frustrates attempts
to convert such rangeland back to grassland [22,27].
SEASONAL DEVELOPMENT :
Tarbush is a rather unusual desert shrub because new growth occurs in
midsummer and flowers appear in late fall. Fruit matures from January
to March [26].
FIRE ECOLOGY
SPECIES: Flourensia cernua | Tarbush
FIRE ECOLOGY OR ADAPTATIONS :
Very little has been published on the effects of fire on tarbush. In
general the open zones and low herbaceous cover in tarbush communities
prevent hot fires unless there is a year of exceptional winter rains
resutling in a heavy stand of annuals to serve as fuels [14].
POSTFIRE REGENERATION STRATEGY :
off-site colonizer; seed carried by wind; postfire years one and two
FIRE EFFECTS
SPECIES: Flourensia cernua | Tarbush
IMMEDIATE FIRE EFFECT ON PLANT :
Killing fires rarely occur in desert communities because of low fuel
loads [14]. However, when such fires do occur, the effect on ecosystem
may be extreme because of the harsh environment and low rate of
productivity [14]. Little is known about specific fire effects on
tarbush.
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
NO-ENTRY
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
Although their study site did not include tarbush, Rogers and Steele
[25] recommended a conservative view toward fire management in deserts
in general because of slow recovery rates in such communities.
REFERENCES
SPECIES: Flourensia cernua | Tarbush
REFERENCES :
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continuous and rotation grazing. Journal of Range Management. 41(1):
78-83. [2878]
2. Barbour, Michael G. 1968. Germination requirements of the desert shrub
Larrea divaricata. Ecology. 49: 915-923. [4212]
3. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals,
reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's
associations for the eleven western states. Tech. Note 301. Denver, CO:
U.S. Department of the Interior, Bureau of Land Management. 169 p.
[434]
4. Brown, David E. 1982. Chihuahuan desertscrub. In: Brown, David E., ed.
Biotic communities of the American Southwest--United States and Mexico.
Desert Plants. 4(1-4): 169-179. [3607]
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semidesert grassland range from 1858 to 1963. Ecological Monographs. 35:
139-164. [3383]
6. Campbell, R. S. 1931. Plant succession and grazing capacity on clay
soils in southern New Mexico. Journal of Agricultural Research. 43(12):
1027-1051. [4035]
7. Chew, Robert M.; Chew, Alice Eastlake. 1965. The primary productivity of
a desert-shrub (Larrea tridentata) community. Ecological Monographs. 35:
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8. Correll, Donovan S.; Johnston, Marshall C. 1970. Manual of the vascular
plants of Texas. Renner, TX: Texas Research Foundation. 1881 p. [4003]
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Weeds common to Mexican and U.S. rangelands: proposals for biological
control and ecological studies. In: Patton, David R.; Gonzales V.,
Carlos E.; Medina, Alvin L.; [and others], technical coordinators.
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Flourensia cernua (tarbush) (blackbrush). Southwestern Veterinarian.
28(2): 113-117. [4323]
11. Emmerich, W. E.; Helmer, J. D.; Renard, K. G.; Lane, L. J. 1984. Fate
and effectiveness of tebuthiuron applied to a rangeland watershed.
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Arizona. Washington, DC: U.S. Department of Agriculture: 957. [3932]
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of the conterminous United States. Special Publication No. 36. New York:
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off-road vehicles. New York: Springer-Verlag: 113-152. [5133]
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for classification and management of native vegetation for food
production in arid zones: Proceedings; 1987 October 12-16; Tucson, AZ.
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Index
Related categories for Species: Flourensia cernua
| Tarbush
|
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