BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Acacia greggii | Catclaw Acacia 



GENERAL BOTANICAL CHARACTERISTICS : 
Catclaw acacia frequently occurs as a 3 to 10 foot (0.9-3 m) tall shrub
but may develop into an upright tree 25 to 30 feet (7.6-9.1 m) tall
[55].  It is often thicket forming and has numerous spreading, slender,
thorny branches [60].  The brown, stout, "clawlike" thorns are about
0.25 inch (0.63 cm) long.  The bark is gray to black and about 0.125
inch (0.32 cm) thick.  Numerous creamy-yellow flowers occur in 1.25 to
2.5 inch (3.1-6.3 cm) long spikes.  The stiff and papery, gray-brown,
legume-type fruits are 2 to 5.5 inches (5-14 cm) long, 0.5 to 0.75 inch
(1.2-1.9 cm) wide, curved or contorted, flattened and constricted
between the seeds [10,55].


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (microphanerophyte)
   Burned or Clipped State:  Hemicryptophyte


REGENERATION PROCESSES : 
Catclaw acacia reproduces sexually by producing an abundance of seeds.
Vegetative regeneration (sprouting) occurs following damage to the
aboveground portion of the plant.

Catclaw acacia flowers are pollinated by insects.  In general, Acacias
begin to produce seed between 2 and 4 years of age [63].  Several,
nearly circular, 0.2 to 0.35 inch (5-9 mm) diameter, dark brown seeds
are encased within a legume-type fruit [42,62].  Catclaw acacia seeds
are principally dispersed by wild animals which eat them [44].  The
seeds have a hard seed coat and can probably remain viable for several
years [63].  Germination has been reported at 60 percent [60].


SITE CHARACTERISTICS : 
Catclaw acacia occurs primarily in semidesert grasslands, brushy
rangelands, Arizona chaparral dominated by turbinella oak (Quercus
turbinella), and desert shrub communities.  In the Sonoran and Mojave
Deserts, it is largely confined to runnels and washes [21,54].  Away
from the washes catclaw acacia occurs as scattered individuals.  When
found on the slopes of a bajada, it is often restricted to the upper
bajada where available moisture is more abundant compared to middle or
lower bajada situations [7].  Catclaw acacia was found to have the
highest water requirements of several desert shrubs tested [37].  This
may partially explain why catclaw acacia, although living in arid
regions, is often confined to dry washes or stream bottoms with
relatively shallow water tables.  In the Chihuahuan Desert, catclaw
acacia is more common outside of desert washes.  It is common in
canyons, on mountain slopes, and in desert shrub communities [12,46].

Associated species:  Along washes in the Sonoran and Mojave Deserts,
associated shrubs include mesquites (Prosopis spp.), whitethorn acacia
(Acacia constricta), blue paloverde (Cercidium floridum), ironwood
(Olneya tesota), desert willow (Chilopsis linearis), and canyon ragweed
(Franseria ambrosioides) [27,54].  In Texas, catclaw acacia often grows
with honey mesquite (Prosopis glandulosa var. glandulosa) [27].

Elevation:  Catclaw acacia is generally found at elevations between
1,000 and 5,000 feet (305-1,524 m) [60].  


SUCCESSIONAL STATUS : 
Catclaw acacia is an invader of desert grasslands.  Its density has
increased over the past 100 years probably as a result of overgrazing
and reduced fire frequencies [21].  

In the Mojave Desert of southern California, catclaw acacia was found to
be a long-lived shrub characteristic of mature, undisturbed desert shrub
communities [59].  However, in low elevation desert shrub communities in
the Sonoran Desert near Tucson, Arizona, it was found to be short-lived.
No plants older than 50 years were found, and most lived for only 20 to
32 years [19].  In the Chihuahuan Desert, following the erosion of
surface soils which overlie very weather-tolerant Tornilla Clay, catclaw
acacia is a midseral species, eventually giving way to climax vegetation
dominated by creosotebush (Larrea divaricata) and tarbush (Flourensia
cernua) [41].


SEASONAL DEVELOPMENT : 
In general, catclaw acacia flowers in May or June, and pods mature
between July and September [55].

Related categories for Species: Acacia greggii | Catclaw Acacia