Regularity: Regularly occurring
States or Provinces
(key to state/province abbreviations)
populations of catclaw acacia [49,161]. Catclaw acacia is common in southern California,
Arizona, western Texas, Baja California, and northern Mexico. Distributions in Nevada, Utah,
and New Mexico are limited [76,121,157]. Catclaw acacia occurs only in the most southwestern
portion of Utah [32,121,157]. Some authors describe catclaw acacia in southern Colorado as
The 2 catclaw acacia varieties have partially overlapping ranges.
Arizona acacia occurs throughout the entire range of catclaw acacia, while Wright acacia
is restricted to New Mexico, western Texas, and Sonora, Tamaulipas, and Nuevo
Leon, Mexico .
A distributional map of catclaw acacia can be accessed through the U.S. Geological Survey.
Regional Distribution in the Western United States
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):
BLM PHYSIOGRAPHIC REGIONS :
6 Upper Basin and Range
7 Lower Basin and Range
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
This description provides characteristics that may be relevant to fire ecology,
and is not meant for identification. Keys for identification are available
Catclaw acacia is a native, long-lived, deciduous, spreading shrub or small tree
[31,104,161]. Depending on the harshness of site conditions, catclaw acacia typically
ranges from 3.3 to 29.5 feet (1-9 m) tall [104,161]. On the Lower Rio Grande River,
catclaw acacia trees measured 35 feet (10.7 m) . The main trunk can be 12 inches
(30.5 cm) in diameter; the bark is commonly 3.2 mm thick, developing cracks and becoming
scale-like with age . Catclaw acacia is heavily armed with stout, curved spines (3-4
mm long) distributed along branches at the internodes [28,71,90,104,167].
Alternate leaves are bipinnate with 4 to 7 leaflet pairs. Leaves measure 0.8 to 2 inches
(2-5 cm) long. Leaflets are between 2 and 12 mm long and are normally hairy
[28,104,167]. Catclaw acacia has extrafloral nectaries on the primary rachis that are
thought to promote mutualistic interactions between catclaw acacia and insects, commonly ants.
The ants provide protection from other insect herbivores, while the extrafloral nectaries provide
the ant with food and water . Catclaw acacia's legume fruits are straight to
twisted, constricted between the seeds, and measure 2 to 4.7 inches (5-12 cm) long by
0.4 to 0.8 inches (1-2 cm) wide [28,54,71,90,104]. Seeds are round and typically 5-7 mm
in size . Although catclaw acacia is a legume, in controlled experiments nodulation has
not occurred [33,178].
Catclaw acacia is highly adapted to harsh desert conditions. A deep root
system, high water use efficiency, high photosynthetic capacity, and use of the
C3 photosynthetic pathway allow catclaw acacia to thrive in harsh desert
climates [12,31,42,65,81]. Zimmerman  observed catclaw acacia roots greater
than 18 feet (5.5 m) deep in southeastern Arizona. On a wash site in the Gold Valley of
the Mohave Desert, 55% of the total catclaw acacia dry weight was root
Catclaw acacia is long lived. Catclaw acacia shrubs were aged from repeat photographs
of Grand Canyon sites. Photographs indicate that 85% of the plants on the sites were at
least 104 years old. Other pictures showed that 5 of 6 plants were at least 120 years old.
Researchers estimated 15% mortality and 27% recruitment in 100 years from the photographs
More info for the term: caliche
Catclaw acacia occupies dry gravelly mesas, canyons, arroyo banks,
rocky hillsides, desert flats, washes, floodplains, and riparian areas in arid
to semiarid southwestern regions [15,86,98,161,172].
|Arizona||below 4,500 feet (1,372 m) [15,71]|
|California||below 6,000 feet (1,829 m) |
|New Mexico||3,500 to 5,000 feet (1,067-1,524 m) |
|Texas||1,000 to 6,000 feet (305-1,829 m) [25,122,161,166]|
|Utah||2,490 to 2,850 feet (760-870 m) [32,167]|
Soils: The desert soils typical of catclaw acacia habitat are low in organic matter, can
be slightly acidic to slightly alkaline, are often shallow (< 12 inches (30.5 cm) deep),
and commonly contain calcium carbonate in the upper 6.6 feet (2 m) of soil. The caliche layer
can be thick and impenetrable [87,89].
Climate: The climate regimes described for catclaw acacia habitats range from
mild to severe. In southwestern semiarid deserts, winters are often mild and
summers are warm to hot. Annual average precipitation predominantly ranges
from 8 to 20 inches (203-508 mm) . Precipitation levels can be much lower in the
Sonoran and Chihuahuan deserts where annual precipitation levels range from 2 to 12
inches (51-305 mm) and 3 to 16 inches (76-406 mm), respectively .
In the lower Colorado Desert of southern California, precipitation is between 2.5 and
4 inches (63.5-102 mm) annually, relative humidity is extremely low, and high
summer temperatures can reach 120 Â°F (49 Â°C) . The chaparral-desert ecotone of southern
California on average receives 12.6 inches (321 mm) of precipitation annually, 69-78% of which
falls from October through April . A bimodal rain pattern is typical for Arizona deserts.
The 14.5 to 17 inches (368-434 mm) of annual rain falls in the winter and early spring and again
in mid- to late summer; late spring and early summer are arid [1,12]. April
through June in Tucson received little over 0.5 inch (12.7 mm) for a recorded 27 year
average . In central Arizona, winter temperatures are between 32
Â°F and 68 Â°F (0 Â°C-21 Â°C) and summer temperatures range from 70 Â°F to 109 Â°F (21 Â°C-43 Â°C).
Southern Nevada weather is also characterized by bimodal precipitation with widespread
winter rain and intense summer monsoons . Maximum high and low temperatures in Clark County,
Nevada, are wide ranging. The winter minimum can be 32 Â°F (0 Â°C) and summer maximums are often
as high as 102 Â°F (39 Â°C) . Temperatures are more extreme for the Desert Plains of
Brewster County, Texas, where lows and highs range from 10 Â°F (-12 Â°C) to 120 Â°F
(49 Â°C). This area receives less than 10 inches (254 mm) of precipitation/year
Key Plant Community Associations
Catclaw acacia, desert willow (Chilopsis linearis), and smoketree (Psorothamnus spinosus)
are typical of southern California's Mohave wash scrub and Mohave Desert wash scrub habitat types.
Wash scrub vegetation also includes cattle saltbrush (Atriplex polycarpa), mesquite
(Prosopis spp.), Mohave rabbitbrush (Ericameria paniculata), white burrobrush
(Hymenoclea salsola), Schott's pygmycedar (Peucephyllum schottii), desert almond
(Prunus fasciculata), and skunkbush sumac (Rhus trilobata var. anisophylla).
Associated with desert wash scrub habitats are California jointfir (Ephedra californica),
stretchberry (Forestiera pubescens var. pubescens), and red barberry (Mahonia haematocarpa) .
In drainages and minor waterways of the Lower Colorado Desert and parts of
the Mohave Desert, catclaw acacia occurs in burrobush (Hymenoclea spp.)-dominated communities with
Anderson wolfberry (Lycium andersonii), desertbroom (Baccharis sarothroides),
cattle saltbush, and Mohave rabbitbrush [65,152].
Creosotebush (Larrea tridentata)-dominated communities are also typical in southern California.
White bursage (Ambrosia dumosa), desert ironwood (Olneya tesota), blue paloverde
(Parkinsonia florida), saguaro (Carnegiea gigantea), and catclaw acacia typify these communities
[88,175]. Catclaw acacia is also typical of desert microphyll woodlands. Blue paloverde, smoketree,
honey mesquite (Prosopis glandulosa), screwbean mesquite (P. pubescens), desert lavender
(Hyptis emoryi), and creosotebush are typical of microphyll woodlands .
The Sonoran mixed woody and succulent scrub vegetation often includes catclaw acacia as well as desert agave
(Agave deserti), brittle bush (Encelia farinosa), ocotillo (Fouquieria splendens), Schott's
pygmycedar, Mohave yucca (Yucca schidigera), and prickly-pear (Opuntia spp.) .
Desert shrub communities of Nevada are dominated by smoketree, desert willow, Mohave desertrue
(Thamnosma montana), brittle bush, triangle goldeneye (Viguiera deltoidea), pale
wolfberry (Lycium pallidum), and catclaw acacia. Typical forb associates are strigose bird's-foot
trefoil (Lotus strigosus var. tomentellus), foothill deervetch (L. humistratus),
whitemargin sandmat Chamaesyce albomarginata, and desert globemallow (Sphaeralcea ambigua) .
Catclaw acacia occurs with desert wash vegetation. Common desert wash shrubs are desert willow,
pale wolfberry, desertsenna (Senna armata), white burrobrush, bladdersage (Salazaria mexicana),
and desert almond .
In Clark County, riparian areas are characterized by saltcedar (Tamarix ramosissma), velvet
mesquite (P. velutina), desertbroom, and catclaw acacia .
Catclaw acacia is typical of several juniper (Juniperus spp.)-dominated communities.
In Pinchot juniper (J. pinchotii) communities of western and north-central Texas,
catclaw acacia, velvet mesquite, and sideoats grama (Bouteloua curtipendula) are common.
In the Rolling Plains of western Texas, common associates are prickly-pears, soapweed yucca
(Y. glauca var. glauca), lotebush (Ziziphus obtusifolia), catclaw mimosa
(Mimosa biuncifera), Texas tussockgrass (Nassella leucotricha), and Arizona cottontop
(Digitaria californica) [94,95]. A similar community in the Rolling Plains of north-central Texas
includes fragrant sumac (R. aromatica), littleleaf sumac (R. microphylla), agarito
(Mahonia trifoliolata), lotebush, threeawn grasses (Aristida spp.), and little bluestem
(Schizachyrium scoparium) .
In the Big Bend region of Texas, catclaw acacia is interspersed in sotol (Dasylirion spp.)-
juniper-lechuguilla (Agave lechuguilla) and shortgrass/juniper communities characterized by the
presence of oneseed juniper (J. monosperma). Other vegetation can include ocotillo, oaks
(Quercus spp.), sumacs (Rhus spp.), gramas (Bouteloua spp.), and threeawns .
Northwest of Uvalde, Texas, catclaw acacia occurs with Ashe juniper (J.
ashei), Texas persimmon (Diospyros texana), mescalbean sophora
(Sophora secundiflora), agarito, and coyotillo (Karwinskia humboldtiana) .
Catclaw acacia also occurs in several mesquite-dominated communities. In the
southern Texas Plains, catclaw acacia is found in mesquite-bunchgrass-annual forb
savannas, mesquite-bristlegrass (Setaria spp.)-forb woodland communities,
and mesquite-granjeno (Celtis pallida)-dominated communities [29,146]. The
mesquite-granjeno community, considered indicative of disturbance, commonly includes
ocotillo, Brazilian bluewood (Condalia hookeri var. hookeri), lime pricklyash
(Zanthoxylum fagara), and sweet acacia (Acacia farnesiana) . In the Chisos
Mountains, the arroyo-mesquite-acacia association includes catclaw acacia, mesquite, mule's fat
(Baccharis salicifolia), and desert willow .
Desert chaparral communities of the Rio Grande Plains and Texano-Mexican desert regions
of Texas also include catclaw acacia [39,50]. Other species common to these desert chaparral
communities are whitethorn acacia (A. constricta), fragrant mimosa (Mimosa borealis), catclaw mimosa, featherplume (Dalea formosa), Brazilian bluewood, knifeleaf condalia
(C. spathulata), and ocotillo .
Tarbush (Flourensia cernua) is often associated with catclaw acacia. In the
creosote-tarbush association in Big Bend, catclaw acacia occurs with mariola
(Parthenium incanum), white ratany (Krameria grayi), Big
Bend barometerbush (Leucophyllum minus), longleaf jointfir (Ephedra trifurca),
crown of thorns (Koeberlinia spinosa), yuccas, and javelin bush (C. ericoides).
In the tobosa (Pleuraphis mutica)-tarbush habitat of Big Bend, grass cover
is sparse. Acacias, velvetpod mimosa (M. dysocarpa), barometerbushes (Leucophyllum spp.),
and snakeweeds (Gutierrezia spp.) dominate the community .
Catclaw acacia is also described with shortgrass-yucca communities. The shortgrasses are
typically sideoats grama, muhly grasses (Muhlenbergia spp.), lovegrasses (Eragrostis
spp.), and bluestems (Andropogon spp.) .
Catclaw acacia is typical in Chihuahuan desert scrub and woodlands. Creosote, tarbush, viscid acacia
(Acacia neovernicosa), barometerbushes, mesquite, desert honeysuckles (Anisacanthus spp.),
and catclaw acacia characterize the creosote scrub vegetation. Apacheplume (Fallugia paradoxa),
splitleaf brickellbush (Brickellia laciniata), granjeno, guajillo (Acacia berlandieri),
little walnut (Juglans microcarpa), and American pistachio (Pistacia mexicana) characterize
sandy arroyo scrub vegetation .
In both mesquite scrub and creosotebush desert communities catclaw acacia is
Catclaw acacia is associated with desert shrub, desert grassland, and arroyo riparian vegetation
[18,26,169]. In the Guadalupe Mountains, catclaw acacia occurs with Pinchot juniper,
lechuguilla, smooth sotol (Dasylirion leiophyllum), mariola, featherplume, threeawns,
sideoats grama, and purple muhly (M. rigida) . In the southern Great Plains of Lea
County, black grama (Bouteloua eriopoda), tobosa, mesquite, whitethorn acacia,
snakeweeds, and catclaw acacia are common .
In the Chihuahuan and Sonoran deserts, catclaw acacia populates the edges of secondary
and lesser riparian systems .
In the Utah juniper (Juniperus osteosperma)/tobosa and redberry juniper (J.
coahuilensis/shrub live oak (Q. turbinella) vegetation types of the
Mogollon Rim, mesquite, redberry juniper, Utah juniper, and catclaw acacia are common.
Singleleaf pinyon (Pinus monophylla), catclaw mimosa, broom snakeweed
(G. sarothrae), and sacahuista (Nolina microcarpa) characterize the
Utah juniper/tobosa community. Yellow paloverde (Parkinsonia microphylla), red
barberry, and Fremont mahonia (Mahonia fremontii) occur in the redberry juniper/shrub live oak community .
Catclaw acacia is recognized in many grassland and shrub/grassland community
types [23,56]. Grass-dominated communities include grassland-mesquite and grassland-desert
shrub vegetation types. Typical grass species in both the grass and shrub dominated vegetation
include gramas, threeawns, bullgrass (Muhly emersleyi), needlegrasses (Achnatherum spp.),
dropseeds, and sacatons (both are Sporobolus spp.). Mesquite-grassland, desert shrub,
desert shrub grassland, and desert shrub-half shrub vegetation types represent the shrub
dominated communities. Mesquite, ocotillo, and acacias can be present in all the aforementioned
shrub-dominated communities. The desert shrub-half shrub community has an understory of
Desert wash and riparian vegetation described for south-central Arizona commonly includes
catclaw acacia, paloverde, and mesquite [59,165,171]. Desert riparian communities are also habitat for
whitethorn acacia, bursage (Ambrosia spp.), Berlandier's wolfberry, desert
ironwood, Drummond's clematis (Clematis drummondii), and fingerleaf gourd
(Cucurbita digitata) .
In central Arizona, catclaw acacia is associated with juniper- and shrub live oak-dominated
vegetation. In the Coconino National Forest, catclaw acacia is found with Utah juniper, shrub
liveoak, manzanitas (Arctostaphylos spp.), bitterbrushes (Purshia spp.), desert
ceanothus (Ceanothus greggii), and mountain-mahogany (Cercocarpus spp.) .
Catclaw acacia is also present in shrub live oak-birchleaf mountain mahogany (C. betuloides),
shrub live oak-mixed shrub, and pointleaf manzanita (A. pungens) communities .
Catclaw acacia in southeastern Arizona associates with desert scrub vegetation types. In the Santa
Catalina Mountains, low densities of catclaw acacia are found in creosotebush desert scrub communities.
Bursage desert scrub vegetation includes fishhook pincushion (Mammillaria grahamii var. grahamii),
triangle bursage (Ambrosia deltoidea), and catclaw acacia. The arroyo margin woodland vegetation is
often characterized by the presence of singlewhorl burrobush (Hymenoclea monogyra), honey mesquite,
and catclaw acacia. Increased densities of catclaw acacia occur in disturbed desert scrub communities with
burroweed (Isocoma tenuisecta) and brittle brush and in spinose suffrutescent desert
scrub communities with slender janusia (Janusia gracilis), yellow paloverde,
and ocotillo .
Habitat: Rangeland Cover Types
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, shrub
SRM (RANGELAND) COVER TYPES :
206 Chamise chaparral
207 Scrub oak mixed chaparral
209 Montane shrubland
211 Creosote bush scrub
412 Juniper-pinyon woodland
416 True mountain-mahogany
503 Arizona chaparral
504 Juniper-pinyon pine woodland
505 Grama-tobosa shrub
507 Palo verde-cactus
611 Blue grama-buffalo grass
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
711 Bluestem-sacahuista prairie
727 Mesquite-buffalo grass
735 Sideoats grama-sumac-juniper
Habitat: Cover Types
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
SAF COVER TYPES :
66 Ashe juniper-redberry (Pinchot) juniper
241 Western live oak
Habitat: Plant Associations
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
KUCHLER  PLANT ASSOCIATIONS:
K023 Juniper-pinyon woodland
K027 Mesquite bosques
K028 Mosaic of K002 and K026
K031 Oak-juniper woodland
K041 Creosote bush
K042 Creosote bush-bur sage
K043 Paloverde-cactus shrub
K044 Creosote bush-tarbush
K045 Ceniza shrub
K053 Grama-galleta steppe
K054 Grama-tobosa prairie
K058 Grama-tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K060 Mesquite savanna
K061 Mesquite-acacia savanna
K062 Mesquite-live oak savanna
K085 Mesquite-buffalo grass
K086 Juniper-oak savanna
K087 Mesquite-oak savanna
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):
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES38 Plains grasslands
FRES40 Desert grasslands
Fire Management Considerations
More info for the terms: cover, fire management, fire-sensitive species, natural, nonnative species, shrub, shrubs
Much of the management regarding fire and catclaw acacia surrounds the reduction
of woody vegetation in once grassland-dominated communities. Also important, and
addressed to a lesser extent, is the fire management of altered ecosystems and
the postfire utilization of catclaw acacia.
Using fire to decrease shrub cover, increase herbaceous cover, and/or alter stream
flows requires repetitive burning and integrated management. Hibbert and others 
suggest prescription burns in chaparral-dominated brush communities alone do not
often significantly reduce shrub cover. Many shrubs in this community, including
catclaw acacia, sprout following fire, and likely only fire-sensitive species are killed.
A combination of fire and other control methods is necessary to substantially
reduce the shrub component from chaparral communities . Humphrey  suggests
that fires every 5-10 years in desert grasslands could control woody vegetation
The effectiveness of fire as a tool to combat increases in nonnative species
is unknown for many desert areas. In saguaro-paloverde dominated Sonoran Desert
communities, postfire rehabilitation measures are necessary following any
prescription fires designed to control nonnative species, as these communities are
not fire adapted . In southeastern Arizona, hawk's eye (Euryops multifidus)
displaced native grasses and shrubs (including catclaw acacia). The response
of hawk's eye monocultures to fire or other natural disturbance processes is
When considering the postfire response of vegetation, postfire utilization is
important. In Anza-Borrego Desert State Park of California, researchers assessed
the utilization of catclaw acacia by herbivores following a July fire. The number
of catclaw acacia sprouts per hectare browsed by wildlife varied by season. For the
number of sprouts produced postfire, see the Fire alone
section above. The utilization of new sprouts was greatest in the fall and winter months.
Sprout browsing results are provided below :
Broad-scale Impacts of Plant Response to Fire
More info for the terms: cover, density, prescribed fire, tree
The majority of fire effects studies indicate that catclaw acacia recovery is rapid.
Postfire sprouting typically makes pre- and postburn densities and coverages similar
for catclaw acacia. However, following a 6,175 acre (2,500 ha) August fire that burned
the Mohave Desert in southern California, catclaw acacia did not recover by the
1st postfire sampling season. On unburned sites within a blackbrush (Coleogyne
ramosissima) community, catclaw acacia cover was 1.7%; on burned sites cover of
catclaw acacia was 0%. In a Joshua tree (Yucca brevifolia)-desert needlegrass
(Achnatherum speciosa)-big galleta (Pleuraphis rigida) community, cover of
catclaw acacia was 0.8% on unburned sites and 0% on burned sites the 1st postfire year.
Below average temperatures were likely a factor in the poor postfire perennial vegetation
The following studies illustrate the more typical postfire response for catclaw
acacia. Following a fire in the Santa Rita Mountains of Arizona, 90%
of catclaw acacia plants in wash areas were sprouting and 100% in the upland
sites were sprouting. The timing of this fire was not clear . Following an
early May fire in a south-central Arizona giant saguaro community, the density
of catclaw acacia on burned and unburned sites was compared. Catclaw acacia
density (plant/0.5 ha) was 44 on unburned sites and 42 on burned sites .
In south-central Arizona following a June fire, the percentage of postfire catclaw
acacia sprouts ranged from 75% to 100% .
In a study of the recovery of Sonoran Desert vegetation following fire, burned areas
were sampled and compared to nearby unburned areas. Given below are the mean heights,
canopy covers, and densities for catclaw acacia on 21-year-old burns, repeatedly burned
sites (4 fires in 30 years), and unburned sites. Both canopy coverage and density
increased with repeated burning :
|Fire history||Height (m)||Canopy cover (%)||Density (number/ha)|
|Repeated fires (4 in 30 yrs.)||2.1||1.9||0.2||0.9||28||57|
After a July fire in Los Angeles County, California, the postfire recovery of
chaparral-desert ecotone vegetation was assessed. Catclaw acacia averaged 166
sprouts per plant following the fire, and survival by postfire sprouting
was high. Density on the ridge sites was lower than on canyon sites. The postfire
response for catclaw acacia is provided below :
|Site||Estimated prefire density (plants/ha)||Postfire density (plants/ha)|
|Site||2 months postfire (sprouts/ha)||4 months postfire (sprouts/ha)||7 months postfire (sprouts/ha)||10 months postfire (sprouts/ha)|
Fire in conjunction with other disturbances:
The following studies involve use of fire and other disturbances as a means
of reducing woody vegetation. The prescribed fire timing for these studies often
differs from presettlement FIRE REGIMES for the areas. In the Rolling Plains and Edwards
Plateau regions of Texas, sites chained then burned reduced catclaw acacia cover by 40%.
Chaining occurred 4 to 5 years prior to a late winter prescription fire, and coverage
change measurements occurred 2 years postfire .
In the San Simon Valley of southeastern Arizona, researchers assessed the effects of grazing
and fire in a shrub-invaded grassland. The average ground cover (number of counts/500 census
locations) for catclaw acacia on all plots was 3.7% prior to any treatments. Fires occurred on
the 20th or 21st of June 1993. Catclaw acacia coverage decreased on burned and grazed plots.
Coverage initially decreased on unburned grazed plots but decreases were short lived. The resulting
changes in ground cover for catclaw acacia are presented below (note: Burned, B; Unburned, UB;
Grazed, G; Ungrazed, UG) :
|Postburn sampling year||1993||1995|
|Ground cover (%)||1.8||6.2||0.4||0.6||3.0||7.8||13.6||8.4|
Another method used to control woody vegetation is repetitive burning. Catclaw
acacia seems tolerant of repeated fires that allow for at least a year between fires;
however, fires that burn within the same year resulted in decreased catclaw acacia cover
and density. In the Rio Grande Plains of Texas, researchers annually and biennially burned
mesquite-acacia savannahs during the dormant (January-February) and growing (July-August)
seasons. Growing season fires burned when air temperatures were between 95
Â°F and 104 Â°F (35 Â°C-40 Â°C), wind speeds were 2.2 to 5.4 m/s, and relative humidity was
20% to 50%. Dormant season fires burned when air temperatures were 44.6 Â°F to 64.4 Â°F
(7 Â°C-18 Â°C), winds were 1.3 to 4.5 m/s, and relative humidity was 65% to
80%. For the biennial burning schedule, a total of 2 fires burned during the
study. The dormant season annual fires occurred for 4 consecutive years while
the growing season annual fires burned for 3 consecutive years. Regardless of
burn prescription, catclaw acacia coverage was greater on burned sites. The
changes in catclaw acacia cover are provided below :
|Burn season||Dormant (January-February)||Growing (July-August)|
|Mean catclaw acacia cover (%)||0.2||1.5||2.6||0.7||2.3||2.0|
In the western South Texas Plains, some sites were burned for 2 consecutive
winter seasons (winter burn). Other sites were burned in the winter and burned
again the following summer (winter-summer burn), while other sites were unburned.
Catclaw acacia cover and density increased following the winter burn and decreased
following the winter-summer burn treatment. The longevity of these changes is unknown.
The changes in catclaw acacia given different patterns of burning are given below :
|Fire treatment||Unburned||Winter burn||Winter-summer burn|
|Mean percent cover||0.3||1.0||0.1|
|Mean density (stems/ha)||36||121||25|
Plant Response to Fire
Following top-kill by fire, catclaw acacia sprouts from the base [34,53,57,91]. Postfire
sprouting is considered prolific by some [57,91]. Following a fire that occurred in early
August, Baldwin  observed basal sprouts as early as late November.
Immediate Effect of Fire
POSTFIRE REGENERATION STRATEGY :
Tall shrub, adventitious bud/root crown
Crown residual colonizer (on-site, initial community)
More info for the terms: cacti, fire frequency, fire regime, fire suppression, fire tolerant, forbs, frequency, nonnative species, shrub, shrubs
Catclaw acacia sprouting following fire is well documented [9,34,53,57,91].
Across the range of habitats occupied by catclaw acacia, historical FIRE REGIMES vary widely.
Semiarid grassland communities likely burned often while extremely arid thorn scrub communities
rarely burned. European settlement and changes in land use have substantially affected the
likelihood of fire in these communities.
Early settlers and explorers described grasslands across large areas of the Southwest, while
descriptions of woody vegetation suggested its restriction to waterways and rocky hillsides
. Decreased fire frequencies in grasslands are often considered the reason for dense
shrub communities in areas once dominated by grasses [2,27]. Frequent fires limited woody
vegetation establishment, maintaining grasslands . Likely the fire frequency in desert
grasslands was such that shrubs were killed in the seedling stage or prior to reaching
reproductive maturity .
High numbers of cattle grazing these grasslands directly and indirectly
promoted the rapid conversion of grassland-dominated areas to shrub-dominated
areas . Grazing animals likely dispersed shrub seed. The selective removal of
grasses decreased the "competition" between grasses and establishing shrubs and
decreased available fuels and eventually fire frequencies [6,58]. McPherson 
predicted future changes in the desert grassland fire regime. Decreases in
cattle grazing and increases in nonnative grasses may favor more frequent fires
than did the last century, yet a return to historic fire frequencies is highly unlikely
due to fragmented fuels and continued fire suppression efforts. However McPherson
recognizes that changes in climate, political agendas, and land use will
continue to affect desert grassland FIRE REGIMES .
Cactus and desert scrub communities:
In the Mohave, Sonoran, and Chihuahuan deserts, the dominant vegetation is widely
spaced, open-branched, and not prone to burning. Biomass production by native
perennial grasses and forbs is low and coverage is sparse, resulting in
noncontinuous fuels [60,159]. Historically in the Mohave Desert, the most arid of
the North American deserts, fires were extremely rare. Fires were also rare in the
Sonoran and Chihuahuan Deserts. The low-growing stature and dense shrub canopies of
the Chihuahuan Desert make this desert slightly more fire prone than the taller and
more widely spaced vegetation of the Sonoran Desert. Portions of the Sonoran and
Chihuahuan deserts that bordered desert grassland systems burned more frequently . The
lack of fire-adapted vegetation in these deserts is further evidence of fire
rarity . Paloverde, saguaro, and other small cacti (pincushions (Scabiosa
spp.) and prickly-pears) do not sprout following fire and are typically killed by even
low-severity fires. It may take a century or more for saguaro and paloverde to
develop from seed to large adult size [34,91].
As in grassland-dominated desert communities, European settlement and land use
have inadvertently altered FIRE REGIMES in desert scrub and thorn scrub
communities. Fires in these communities are more frequent than those that
occurred historically [1,34,159]. The introduction and subsequent expansion of several
nonnative species including red brome (Bromus madritensis spp. rubens),
cheatgrass (B. tectorum), mediterranean grasses (Schismus spp.), buffelgrass
(Pennisetum ciliare), and potentially ripgut brome (B. diandrus) increased
fire risk in many desert scrub communities [1,34,119,159]. The displacement of native ephemeral
species by these successful nonnative species creates easily ignited communities and supports
large fires [91,119]. Increased fire frequencies in these fire-intolerant communities will
likely alter their composition by removing fire sensitive species and increasing fire
tolerant species [34,159]. Alford and Brock  studied the postburn vegetation response
in fire sensitive Sonoran desert communities and found several native species (saguaro,
foothill paloverde, white ratany, creosote bush, wolfberry) decreased while purple threeawn,
senna, and red brome increased .
For further information regarding FIRE REGIMES and fire ecology of
communities and ecosystems where catclaw acacia is found, see the FEIS species
reviews for the plant community or ecosystem dominants listed below:
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|California chaparral||Adenostoma and/or Arctostaphylos spp.||115]|
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||74,115]|
|bluestem-Sacahuista prairie||Andropogon littoralis-Spartina spartinae||< 10|
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||5-100 |
|plains grasslands||Bouteloua spp.||115,174]|
|blue grama-needle-and-thread grass-western wheatgrass||Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii||115,131,174]|
|blue grama-tobosa prairie||Bouteloua gracilis-Pleuraphis mutica||< 35 to < 100|
|California montane chaparral||Ceanothus and/or Arctostaphylos spp.||50-100|
|paloverde-cactus shrub||Cercidium microphyllum/Opuntia spp.||115]|
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1,000 [7,135]|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||< 35 to < 100|
|blackbrush||Coleogyne ramosissima||< 35 to < 100|
|juniper-oak savanna||Juniperus ashei-Quercus virginiana||< 35|
|Ashe juniper||Juniperus ashei||< 35|
|creosotebush||Larrea tridentata||< 35 to < 100|
|Ceniza shrub||Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa||< 35|
|mesquite-buffalo grass||Prosopis glandulosa-Buchloe dactyloides||< 35|
|Texas savanna||Prosopis glandulosa var. glandulosa||< 10|
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||115]|
|oak savanna||Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium||2-14 [115,163]|
|little bluestem-grama prairie||Schizachyrium scoparium-Bouteloua spp.||115]|
*fire return interval varies widely; trends in variation are noted in the
More info on this topic.
More info for the terms: climax, cover, mesic, succession
The concept of succession, in which community composition changes over time as a
site is modified by past and present species, was developed in mesic eastern
forests and does not apply well to southwestern desert ecosystem dynamics. In eastern forest
ecosystems, pioneer species are typically not present in climax communities. In southwestern
deserts, species that make up the predisturbed vegetation are the same species that make up
the recovering vegetation . While true Clementsian succession does not occur in semiarid and arid
ecosystems, it is possible to see shifts in species dominance in relation to
disturbance . The continued use of many traditional succession terms to
explain desert community change or development is likely due to the lack of more
In the case of catclaw acacia, the terms "postclimax", "disclimax", and
"subclimax" have been used to describe this species' response to
various disturbances. In the southern desert plains, mesquite-acacia vegetation
that increased in abundance and extent with disturbance is labeled "postclimax"
. Others classified catclaw acacia as an "invader" species when it appeared
late in the stages of community degradation in the Guadalupe Mountains of New Mexico .
In the south Texas Plains, catclaw acacia is one of several species considered dominant
in the mesquite-granjeno disturbance community type . Dick-Peddie and Alberico 
described vegetation dominated by beebrushes (Aloysia spp.), lechuguilla, tulip prickly pear
(Opuntia phaeacantha), blue grama (Bouteloua gracilis), sideoats grama, whitethorn
acacia, and catclaw acacia as "disclimax" vegetation maintained through grazing and fire
reduction. Whitfield and Anderson  considered sacaton vegetation, typically including catclaw
acacia, an edaphic "subclimax" community persisting on heavy clay or alkali soils of
washes and flood plains.
When studying different-aged debris flows in the Grand Canyon of Arizona, Bowers and others
 found catclaw acacia in almost all but the youngest and oldest communities. The percent
coverage and densities of catclaw acacia on different aged debris flows are presented below.
|Time (in years) since last flow||5||28||28||32||43||47||55||240||285||485||3100|
More info for the terms: cactus, root crown, tree
Catclaw acacia reproduces sexually through seed production, and when top-killed,
catclaw acacia regenerates asexually through root crown sprouts [9,34,53,57,91].
No information is available on this topic.
Catclaw acacia is considered an important honey plant [71,82,122], and likely bees
are the chief flower pollinators.
Seed predation is common for catclaw acacia (see
IMPORTANCE TO LIVESTOCK AND WILDLIFE section).
Dispersal of catclaw acacia seed can result from animal movements and abiotic
disturbances. In the Chihuahuan Desert of Arizona and New Mexico, researchers found
that plant material used by cactus wrens to construct nests often include seeds.
One of 12 cactus wren nests contained catclaw acacia seed. Collections are commonly
made greater than 65.6 feet (20 m) from the nest site making nest construction a seed
dispersal mechanism . Likely grazing animals disperse catclaw acacia seed [6,58].
No studies addressed seed viability once passed through the digestive tract.
Following heavy rainfall (76% of annual average) in San Diego County, California,
612 catclaw seedlings per hectare occurred on a site void of mature catclaw acacia.
However, catclaw acacia occurred in washes upstream from the site. Most likely
the storm relocated seeds from the wash to produce the catclaw acacia seedling
Seed bank development by catclaw acacia is not well understood. While some suggest a
persistent seed bank , others recovered no catclaw acacia seed from 240 soil samples taken
from herbicide treated and control sites in the Chihuahuan Desert of Texas. Researchers
suggested heavy seed predation, reliance on a short-lived seed bank, and/or dependence on asexual
reproduction to explain the lack of catclaw acacia seed in
soils samples .
Temperature and moisture requirements must be met for catclaw acacia seed to germinate.
Bowers  suggests that August and September seed germination is triggered by 1.2
inches (30 mm) or more of rainfall. Jordan and Haferkamp  suggest temperatures above 45
Â°F (7.2 Â°C) are required to germinate catclaw acacia seed. In California's Joshua Tree
National Monument, catclaw acacia germinated only in August and September . However,
factors other than temperature and moisture may affect germination. Even when able
to control growing conditions, horticulturists were unable to germinate seed
collected from plants in 1927, while seed collected in 1929 germinated .
Site conditions and early disturbances affect catclaw acacia seedling
development. Perkins and Owens  found seedling growth was greatest when
plants were exposed to full sunlight. When defoliated early in development, catclaw acacia
seedlings had significantly (p<0.01) less total biomass than nondefoliated seedlings.
Many Sonoran Desert species including catclaw acacia are described in a seedling identification
key. Descriptions are provided for catclaw acacia seedlings from 1 to 45 days after emergence. A strong
nitrogen odor is given off when seedlings are uprooted. This same trait is
described for other Acacia spp. but not all Fabaceae species .
Catclaw acacia readily reproduces vegetatively following the removal of aboveground biomass
Growth Form (according to Raunkiær Life-form classification)
More info for the term: phanerophyte
RAUNKIAER  LIFE FORM:
Life History and Behavior
Timing of flowering and fruit set in catclaw acacia varies only slightly across
its distributional range. In Texas flowers are present from April through
October, and fruits set in July persist through the winter months .
In New Mexico catclaw acacia flowers from April to September . Catclaw acacia
flowers from May through October in the Mojave Desert of Nevada . Plants monitored
in San Diego County, California, produced leaves and flowers simultaneously and were
leafless for approximately 1 month's time in March and April .
Molecular Biology and Genetics
Barcode data: Acacia greggii
Statistics of barcoding coverage: Acacia greggii
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Catclaw acacia is able to withstand heavy grazing pressure. Defoliated plants showed
significantly more shoots (p=0.05), greater branch length (p<0.01), and leaf density
(p=0.02) in the current year's growth than did control plants. Following defoliation treatments,
plants were undisturbed for 1 year. Branch length of these previously defoliated plants was
significantly (p=0.03) less than control plants. Spine density was significantly (p=0.04)
greater on defoliated mature plants compared to undisturbed controls .
Many have researched the control of catclaw acacia in once grassland-dominated ecosystems.
Mechanical control [22,134], chemical control [68,101,102,114,160], and combined control
measures are described .
Relevance to Humans and Ecosystems
Other uses and values
Indigenous people found several uses for catclaw acacia. The Akimel O'odham or
Gila River Pima ate catclaw acacia seeds when better foods were not available;
the author considered catclaw acacia a "starvation food" . The Chauilla
Native Americans of southern California utilized catclaw acacia wood as fuel and ate
catclaw acacia beans. The pods were eaten fresh, dried, or ground into powder; the
bitter taste of the pods suggests catclaw acacia was not preferred. However,
all Chauilla interviewed recalled catclaw acacia as a food source .
Moore  suggests several other catclaw acacia medicinal properties. Pods are
used to make an eyewash to treat conjunctivitis. Leaves and pods when ground into
powder will stop small amounts of bleeding and soothe chafed skin or diaper rash.
When this powder is made into a tea, it can be used as an antimicrobial wash or drunk
to treat diarrhea and dysentery. Native Americans used catclaw acacia to soothe sore
flank and back muscles of their horses. The flowers and leaves in tea can treat nausea,
vomiting, and hangovers. The thick, sticky catclaw acacia root when made into tea treats
sore throats, mouth inflammations, and coughs .
Catclaw acacia wood is strong, hard, tight grained, and heavy [50,71,161]. It is used
for cabinets, turnery, and fencing . The contrasting reddish brown heart wood and
yellow sapwood makes it valuable for making souvenirs .
Value for rehabilitation of disturbed sites
Catclaw acacia is valuable in reclaiming asbestos, mining, and other disturbed
sites. The use of catclaw acacia seedlings predominates in revegetation efforts,
but catclaw acacia was in a seed mixture used to successfully revegetate a pipeline corridor
in Arizona. Using tillage, mulch, and site-adapted seed, the revegetated site
closely resembled nearby undisturbed sites 10 years after planting . On an
abandoned asbestos milling site in Globe, Arizona, catclaw acacia transplants were
100% successful even given rodent herbivory in the area . Catclaw acacia
seedlings survived on a gold mine spoils site in the Mohave Desert. Survival rates
were not reported . Catclaw acacia was one of many species used to revegetate
disturbed sites (road side cuts, mining sites, eroded hillsides, and gullies) by
the Utah Division of Wildlife Resources and other cooperators. In southern
desert shrubland areas, catclaw acacia established well when transplanted,
spread well by seed, and survived on alkaline or acidic soils. In categories of
natural vegetative spread, growth rate, soil stability, and disturbance tolerance,
catclaw acacia received mid level ratings .
As transplants are favored over seed, the following insights regarding catclaw acacia
seedling production may prove useful. When growing catclaw acacia seed in containers,
a tall container is recommended to house the rapidly developing root system .
Heydari and others  found the root length of catclaw acacia seedlings was greater
than 23.6 inches (60 cm) 4-5 months after planting on watered sites. Fidelibus and Bainbridge
 found seedling growth and survival were not compromised when bareroot seedlings were
transported to the field site in moist fabric rather than in greenhouse containers.
Senegalia greggii is a species of Senegalia native to the southwestern United States and northern Mexico, from the extreme south of Utah (where, at 37°10' N it is the northernmost naturally occurring Senegalia species anywhere in the world) south through southern Nevada, southeast California, Arizona, New Mexico and western Texas to Baja California, Sinaloa and Nuevo León in Mexico.
Common names include Catclaw Acacia, Catclaw Mesquite, Gregg's Catclaw, Devil's Claw, Paradise Flower, Wait-a-minute Tree, and Wait-a-bit Tree; these names mostly come from the fact that the tree has numerous hooked prickles with the shape and size of a cat's claw, that tend to hook onto passers-by; the hooked person must stop ("wait a minute") to remove the prickles carefully to avoid injury or shredded clothing. (Note: "Cat's Claw" is also used to refer to Uncaria tomentosa, a woody vine found in the tropical jungles of South and Central America)
S. greggii is most common in arroyos where its roots have access to deep water. Its seeds require physical scarification in order to germinate. This effectively prevents germination unless a flash flood disturbs the area and deposits enough water to increase the likelihood that seedlings will be able to establish deep enough roots to survive the dry season. Catclaw is fully drought deciduous and will usually lack leaves for most of the year. S. greggii has extrafloral nectaries, a trait shared with other senegalias. A tentative connection has been made between these glands and insects that would suggest a mutualistic relationship (as found in other Senegalia species). Ants are known to use the glands as a source of food and water, and may provide some defense for the plant against herbivorous insects. Like other arroyo trees in family Fabaceae, S. greggii is frequently afflicted with Desert Mistletoe, Phoradendron californicum. Unlike other legumes, S. greggii is not known to form root nodule associations with nitrogen-fixing bacteria.
Devil's Claw may be an example of an evolutionary anachronism, in which the range and renewal of the species is limited due to the extinction of the mammallian megafauna responsible for seed dispersal. Within this model, the scarification required to germinate the seeds would have occurred during the chewing and digestion of the fruit by a large mammal, who later passes the seed intact some distance from the original tree.
It is a large shrub or small tree growing to 10 m (33 ft) tall with a trunk up to 20–30 cm (7.9–11.8 in) diameter. The grey-green leaves are deciduous, and bipinnate, divided into 1-3 pairs of pinnae, each pinna 2–3 cm (0.79–1.18 in) long with 10-18 leaflets that are 3–6 mm (0.12–0.24 in). Pinnae are most frequently in two pairs, with the proximal pair perpendicular to the petiolule and the distal pair forming a V at the tip. The flowers are produced in dense cylindrical spikes, each flower with five yellow 3 mm (0.12 in) petals and numerous yellow 6 mm (0.24 in) stamens. The fruit is a flat, twisted legume (pod) 6–15 cm (2.4–5.9 in) long, containing several hard, dark brown seeds. The seed pod is constricted between seeds (a loment), and seed dispersal occurs both through dehiscence and breaks at these constrictions.
S. greggii, even though it is used as forage for livestock, contains a potentially poisonous cyanogenic glycoside called prunasin. Mature seeds are to be avoided, as the native people did. S. greggii young, unripe beans were gathered and eaten by desert tribes of North America, including the Chemehuevi of the Southern Paiute, the Pima, and the Cahuilla. The Cahuilla also ground the dried beans for mush and cakes, while the Havasupai ground it to make flour for bread. The Seri ground the beans to meal then mixed it with water and sea lion oil for porridge. The Diegueno used S. greggii as food for domesticated animals.
The Cahuilla and Pima used the fibers for sturdy construction material and firewood. The Havasupai split the twigs and used them for basketry, but also used the twigs as a broom to brush off metates. The Papago also used the broken twigs for baskets, and were curved to make intricate weaves in the baskets. The Pima used the dried bushes to pile them to make a brush fence. The branches were used to make cradle frames as well.
The Papago fitted the branches around the deer hunters' heads to make a disguise as a deer, and the buds and blossoms were dried to make perfume sachets by the women. The sticks were also used to dislodge saguaro fruits from the cactus body, and rods were curved to flesh animal skins. The Pima made bows out of the wood.
Some chemical compounds found in Senegalia greggii
- Barlow, C. (2000). The Ghosts of Evolution: Nonsensical fruit, missing partners and other ecological anachronisms. Basic Books:NY.
- Jepson Manual Treatment: Senegalia greggii (as Acacia greggii)
- U.S. Forest Service FEIS Database: Senegalia greggii (as Acacia greggii)
- Lawor, Elizabeth Jane (1995). Archaeological Site-formation Processes Affecting Plant Remains in the Mojave Desert.. University of California, Riverside.
- Range Shrubs
- Interactive Distribution Map of Senegalia greggii (as Acacia greggii)
Names and Taxonomy
Gray (Fabaceae) [28,67]. Accepted varieties are:
A. g. var. greggii Gray, Arizona acacia [28,67,70]
A. g. var. wrightii (Benth.) Isley, Wright acacia [28,67,70]
Throughout this review, catclaw acacia will refer to both varieties, A. g.
var. greggii and A. g. var. wrightii. When citing literature
that distinguishes variety, A. g. var. greggii will be referred to as
Arizona acacia, and A. g. var. wrightii will be referred to as Wright
acacia. When information is provided that pertains to the Acacia genus without
indicating species, it will be noted as Acacia spp.
Hybrid: A. greggii hybridizes with A. berlandieri to
produce Acacia ÃÂ emoryana Benth. [66,83].
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