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Species
Prosopis velutina Woot.
IUCN
NCBI
EOL Text
More info for the term: natural
The main distribution of velvet mesquite is confined to central and
southern Arizona, extreme southwestern New Mexico, and adjacent northern
Mexico [56,73]. The eastern boundary of its range is near the
Continental Divide in southern New Mexico [115]. The Continental Divide
forms a natural boundary between populations of velvet mesquite and
honey mesquite (var. uncertain) [115]. In California, velvet mesquite
is represented by only a few individuals that occur in Imperial,
Riverside, and Kern counties [57]. This population is believed to be
from human introductions. A small, isolated population occurs in the
Rio Grande Valley, near El Paso, Texas [65], that is also thought to be
introduced.
More info for the term: geophyte
Geophyte, growing points deep in soil
Initial-offsite colonizer (off-site, initial community)
More info for the terms: cover, shrubs, tree
Velvet mesquite provides needed security cover for large wildlife
species. Its invasion into grasslands has benefited brush dependent
wildlife species such as the collared peccary and mule deer [2,15].
Southern Arizona studies indicate that velvet-mesquite-dominated
vegetation types are a preferred habitat of desert mule deer, but that
white-tailed deer seldom use velvet mesquite habitats [2,108]. Small
mammals such as antelope jackrabbits, woodrats, and kangaroo rats are
often found in brushy velvet mesquite habitats. A southern Arizona
study found that 99 percent of available velvet mesquite shrubs housed
Merriam kangaroo rat dens [103]. In fact, many species of rodents place
their burrows under the protection of velvet mesquite plants [76].
Found in desert environments, velvet mesquite provides shade for
livestock and wildlife. Jackrabbits often use the shade that mesquites
provide to help regulate their heat balance [76].
Brushy velvet mesquite ranges provide excellent habitat for the
zebra-tailed lizard, desert spiny lizard, western whiptail, and tree
lizards. The desert spiny lizard and tree lizards are primarily
arboreal and are often found in mesquite trees. Tree lizards may
aggregate in large numbers in the winter, using the underside of
protruding velvet mesquite bark as hibernating sites [47].
Velvet mesquite riparian communities provide important habitat for
numerous nesting bird species during both summer and winter. Along the
lower Verde River floodplain in Arizona, 19 species and 244 pairs of
breeding birds per 100 acres (40 ha) were found in a velvet mesquite bosque
community [117]. In another velvet mesquite bosque community in
southern Arizona, 476 pairs of nesting birds were found per 100 acres
(40 ha) [46].
More info on this topic.
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):
7 Lower Basin and Range
12 Colorado Plateau
Velvet mesquite plants contain numerous, dormant buds on an underground
stem. Soil and rough bark sufficiently insulate the buds from the heat
of most fires [22,51]. Even 8-month-old seedlings have sufficiently
developed underground stem buds to allow some plants to survive burning
[19]. Following top-killing fires, numerous sprouts arise from the
underground buds.
Numerous wild and domestic animals consume and disperse velvet mesquite
seed. Seed from off-site plants can be transported to burned areas by
animals.
Velvet mesquite's fruits are nutritious. The thick and spongy pericarp
is high in sugars and the seeds contain large amounts of protein.
Fruits also supply a good source of minerals for herbivores. Because
plants fix nitrogen, the leaves are high in protein.
Nutritional information concerning velvet mesquite fruit is presented
below [4]:
% N % crude % fat % fiber % ash % total
protein sugars
seed 5.13 29.44 5.68 7.12 3.83 ----
pericarp 1.13 6.88 2.24 23.48 5.52 31.6
whole pod 1.95 11.81 2.36 22.61 4.83 22.2
The mineral composition of velvet mesquite fruit is as follows [4]:
% Ca % Mg % Na % K ppm Cu ppm Zn ppm Mn ppm Fe
seed .26 .18 .06 .68 13.6 49.6 24.2 46.6
pericarp .63 .09 .04 1.16 6.4 9.6 11.6 48.8
whole pods .53 .09 .03 1.27 8.3 26.4 14.5 40.4
Nutritional information concerning velvet mesquite leaves and fruits
collected in southern Arizona is presented below [110]:
season % protein % K P/Ca ratio % In Vitro
collected digestibility
leaves spring 17.6 .23 .28 62.3
fruit summer 9.5 .16 .23 66.5
leaves autumn 16.4 .10 .05 44.8
leaves winter 15.8 .10 .05 44.9
This mesquite is found below 1700 m in desert washes and plains in Yavapai County, Arizona east and south to western Texas and northern Mexico. It is common in Sonora at least as far south as Guaymas and uncommon in California, being found in the San Joaquin Valley, and the central and south coasts. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Velvet mesquite reproduces sexually by producing an abundance of seeds.
Vegetative regeneration commonly occurs following damage to the
aboveground portion of the plant.
Seed production: Velvet mesquite flowers are pollinated by insects,
predominately bees. Although mesquite inflorescences contain hundreds
of flowers, generally only one to a few fruits develop per inflorescence
[113]. This ensures enough resources for proper development of a
limited number of fruits per inflorescence. Insufficient soil moisture
can cause early spring flowers to be entirely aborted before pollination
occurs. New flowers will develop if there is sufficient rainfall later
in the season. Due to fluctuations in the weather, fruit production can
be quite variable from year to year for plants growing in semi-desert
grasslands [51]. Plants growing along washes or in riparian areas,
where they have access to permanent underground water, produce fruit
quite predictably from year to year. The seeds are glossy brown, oval,
0.2 to 0.28 inch (5-7 mm) long and 0.12 to 0.2 inch (4-5 mm) wide [6].
There are about 13,418 seeds per pound (29,573/kg) [51]. The
reproductive potential of velvet mesquite is often greatly reduced by
seed-feeding insects. The life cycle of Bruchid beetles (Algarobius
spp.) and the amical weevil (Bruchus amicus) are dependent upon mesquite
fruit. Female beetles and weevils lay eggs on the pods and as the
larvae hatch they burrow into the fruits and feed on the seeds [71]. A
small, brown, circular spot often forms on the pod showing evidence of
larvae entry. Fruit collected within a 25 mile (40 km) radius of Tucson
had as high as 70 to 80 percent of the seeds attacked by insect larvae
[51]. Although flower and pod attacking insects significantly reduces
the production of pods and viable seeds per plant, velvet mesquite
produces pods in such abundance that numerous viable seeds are still
produced [71].
Seed dispersal: Animals - Pods are eaten and then dispersed by domestic
and wild animals. Cattle and rodents are the primary dispersers of
velvet mesquite seed; numerous other animals also consume the pods [see
Importance To Livestock And Wildlife]. Studies involving honey mesquite
showed that when pods were fed to livestock, 97, 79, and 16 percent of
the seeds passed through the digestive tracts of horses, yearling
steers, and ewes with the greatest number of seeds passing through
between 42 and 60 hours after feeding [43]. When velvet mesquite seed
pods were fed to domestic sheep, 32 percent of the seed passed through
the digestive tract intact and sound. Examination of cattle dung piles
on velvet mesquite-grasslands at a time when ripe pods were plentiful,
showed that each dung pile averaged 1,535 seeds, of which about 65
percent were sound [51]. Because it takes days for seeds to pass
through the digestive tracts of domestic animals, seeds are dispersed
great distances. The digestive juices of domestic animals also kills
some seed-eating insects [89]. Many rodents collect and store velvet
mesquite seeds or pods in caches. Merriam kangaroo rats often transport
seeds more than 100 feet (30 m) [51,103]. Seelings commonly germinate
from uneaten seed in rodent caches [103,105]. Sampling in 1948, 1950
and 1951 on the Santa Rita Experimental Range, showed that during these
years 37.4, 23.3, and 8.4 percent of seedlings emerging, respectively,
were from kangaroo rat caches [51].
Water - Velvet mesquite pods float and are carried downslope by flowing
water. Intense summer rainstorms often cause overland flows of water on
areas with only minor slope gradients in the Sonoran Desert. On the
Santa Rita Experimental Range, seedlings are abundant in the alluvium
along small water courses and in the alluvial fans formed by these
drainages [51].
Seed viability and germination: Velvet mesquite seeds contain a bony,
protective endocarp. Scarification of this hard seed coat must occur
before the seed can germinate. Scarification of the seed occurs
naturally when seeds pass through the digestive system of animals.
Seeds remaining in pods not consumed by animals remain dormant until the
seed coat is broken by weathering. Tests of various aged sound seed
showed that 1- to 45-month-old scarified seed displayed better than 94
percent germination, 1-month-old unscarified seed had only 20 percent
germination, and germination of 5- to 45-month-old unscarified seed
never exceeded 7 percent. Most germination of velvet mesquite seeds
within pod segments buried 1 inch (2.5 cm) below the soil surface in
Arizona occurred within 3 years, with about 35, 9, and 1 percent
germination occurring 1, 2, and 3 years after planting [118]. The
protective endocarp allows seeds to remain viable for long periods.
Seeds in dry storage have remained viable for decades. Germination of
stored seed has been reported as follows [51]:
Age in years Germination of sound seed
Unscarified Scarified
11 ---- 97.5%
44 20% 60%
50 30% 60%
Planting of unscarified seeds in the field showed that germination of
seeds within pod segments was 2 to 3 times greater than that of hulled
seeds. Over a 3-year period, 44.7 percent of seeds planted in pod
segments germinated, but only 15.8 percent of hulled seeds germinated
[118].
Velvet mesquite seeds germinate over a wide range of temperatures and
soil conditions. Better than 80 percent germination was achieved at
temperatures ranging from 61 to 100 degrees F (16-38 C) [112]. High
germination occurs over a wide range of soil pH (4-10) and on soils of
high salinity [112].
Seedling emergence and establishment: Velvet mesquite seeds must be
covered with a small amount of soil or dung for seedlings to become
established. Seeds that germinate on the soil surface normally die. In
Arizona, seedling emergence is most common during July and August when
soil moisture is adequate due to summer rains, but may occur anytime
between March and November [51]. Recent research on honey mesquite in
Texas suggests that past grazing history has little influence on
mesquite establishment in grasslands, but that herbaceous defoliation
during the year of seed dispersal is a key factor [16]. In semi-desert
grasslands of Arizona, velvet mesquite seedling establishment was
similarly found to be much higher in grazed habitats and in areas
denuded by drought than in vigorous stands of perennial grasses [51].
In true desert environments, conditions that favor plant establishment
may occur only once every 5 to 10 years following intense rains [123].
Because velvet mesquite seeds can remain viable for several years, seeds
stored in the soil may germinate following such events. In a crater in
northern Sonora, Mexico, velvet mesquite seedlings became established
following two unusually intense rainfalls in 1970 and 1972 which induced
ponding [120].
Seedling development: Soil moisture stress and browsing by rodents and
insects often result in very slow development of velvet mesquite
seedlings. Seedlings exhibit more rapid growth on coarse-textured soils
than fine-textured soils. Velvet mesquite seedlings rapidly develop a
deep root system which allows them to reach water and nutrients for
later growth before upper soil layers become dry [13]. Top and root
growth of seedlings found on upland sites at the Santa Rita Experimental
Range that were protected from browsing was as follows [51]:
age in months average maximum plant average maximum root
height penetration
(inches) (centimeters) (inches) (centimeters)
9 2.1 5.3 20.1 51.0
14 3.0 7.6 27.1 68.8
24 3.7 9.4 ---- ----
38 4.5 11.4 33.4 84.8
50 5.0 12.7 ---- ----
Another study found that on upland sites, 94 percent of all velvet
mesquite plants established over a 17-year period were under 3.0 feet
(0.9 m) tall [50].
Vegetative regeneration: Velvet mesquite plants have numerous perennial
dormant buds located along an underground stem. These dormant buds
generally occur from the basal portion of the plant to about 6 inches
(15 cm) below the soil surface [95]. When aboveground growth is damaged
or killed, new sprouts arise from the bud zone.
More info for the term: tree
Livestock: Cattle, horses, sheep, goats, hogs, mules, and burros eat
large quantities of ripe velve mesquite fruit when available [29].
Livestock often remove the fruits as high on the tree as they can reach
and eat fallen pods lying on the ground [3,51]. Livestock do not
consume the foliage to any great extent [80]. Foliage consumption by
livestock is greatest during drought years, especially in the early
spring when other forage is lacking [29,49]. Most livestock consume
mesquite (Prosopis spp.) flowers when available [80]. In some areas of
Mexico, mesquite beans are collected, ground, and fed to cattle [31].
Wildlife: Velvet mesquite annually provides an abundant and nutritious
food source for numerous wildlife species when the pods ripen between
June and late October [51,71]. The beans and seeds form an important
part of the diet of mice, kangaroo rats, woodrats, chipmunks, ground
squirrels, rock squirrels, cottontail rabbits, skunks, quail, doves,
ravens, jackrabbits, the racoon, coyote, collared peccary, white-tailed
deer, mule deer, wild turkey, and mallard [2,9,29,51,52,101,105,122].
Many species of small rodents derive a large portion of their diet from
velvet mesquite seeds. These animals frequently store seeds and whole
beans in dens or caches [51]. Many species of birds eat flower buds and
young inflorescences of velvet mesquite. Insectivorous birds feed on
the numerous insects that are attracted to velvet mesquite flowers
[113]. Many species of quail eat mesquite buds and flowers in the
spring, and seeds during the fall and winter [122]. Mesquite seeds
often comprise 10 to 25 percent of the diet of Gambel's and scaled
quails [31]. Collared peccaries in Arizona feed heavily on velvet
mesquite beans from July to September [34]. In south-central Arizona,
velvet mesquite fruits comprised 9 percent of the white-tailed deer's
and 29 percent of the mule deer's summer diet, but use of any velvet
mesquite parts during the rest of the year was minimal [82]. A study in
semidesert grass-shrub habitats of southern Arizona found mule deer use
of velvet mesquite to vary seasonally. Velvet mesquite leaves comprised
0.3 percent of the mule deer's diet during the spring, 2.9 percent
during the autumn, and 4.9 percent during the winter, while fruits
comprised 24.0 percent of the mule deer's summer diet [110].
Mesquite browse is generally not a very important wildlife food source.
The wild turkey, ground squirrels, cottontails, and woodrats consume
some leaves [9,52]. Jackrabbits often consume large amounts of mesquite
and may crop leaves, buds, and bark as high as they can reach [124].
Velvet mesquite seedlings up to about 2 years old are often eaten by
jackrabbits and cottontails. Kangaroo rats frequently eat recently
germinated velvet mesquite seedlings [51]. Locally, mule deer consume
large quantities of mesquite foliage, but this may reflect a scarcity of
other browse rather than a preference for mesquite [109].
More info for the terms: shrub, tree
Velvet mesquite is a deciduous, thorny shrub or small tree. Plants may
grow into single-stemmed trees up to 50 feet (15 m) tall with a trunk
diameter up to about 2 feet (61 cm) or they may develop into an erect,
multistemmed bush [51,69]. The largest trees are often found along
water courses or floodplains where the deep root system has access to
year-round water. In general, tree forms are found on alluvial soils
whereas smaller forms are found on tighter, rocky upland soils [51].
Velvet mesquite has a strong tendency for apical dominance and a
well-developed crown [89]. Undisturbed plants therefore develop into
single-stemmed trees. If the aboveground growth is damaged or removed,
such as by freezing weather, drought, fire, trampling, browsing, or
cutting, dormant buds located on the underground stem initiate new
growth, resulting in the many-stemmed growth form. In many semi-desert
grasslands the shrubby form predominates because years of browsing,
trampling, and repeated chemical or mechanical control attempts resulted
in many plants sprouting from the base [114].
The bark on older branches and the trunk is dark brown, rough and thick,
and separates into long narrow strips [75]. Young branches may be green
and photosynthetic [119]. Stout, yellow thorns are about 0.25 to 1 inch
(0.6-2.5 cm) long and generally occur in pairs on young branches [75].
The yellowish-green flowers occur on a 2 to 3 inch (5-7.6 cm) long
cylindrical, pedunculate, spikelike raceme [51,113]. The flattened,
straight or curved legume-type fruits are 3 to 8 inches (7.6-20 cm)
long, occur singly or in drooping clusters, and may be yellow, red,
black, or mottled [114].
Velvet mesquite is a facultative phreatophyte which extracts moisture
from a large volume of soil through a well-developed root system. In
true desert environments plants are often restricted to wash areas where
the taproot can penetrate several meters to underground water. Roots
probably do not extend much more than 50 feet (14 m) [67,86], although
they have been found at depths of 175 feet (53 m) [99]. Plants growing
on sites where the soil is shallow or moisture does not penetrate deeply
have an extensive system of lateral roots that reach several meters away
from the plant base1w. Under these circumstances laterals are often
concentrated in a zone 6 to 12 inches (15-30 cm) below the soil surface
[90]. Plants can also extract water from soil held at high matric
forces [89]. These adaptations allow velvet mesquite to retain an
entire complement of leaves during all but the most severe droughts.
The primary botanical characteristics used to differentiate velvet
mesquite, honey mesquite, and western honey mesquite are the size,
shape, and hairness of the leaflets. Velvet mesquite leaflets are
generally short, hairy, and closely spaced; those of honey mesquite are
long, linear, glabrous and widely spaced; those of western honey
mesquite are intermediate [6]. Several manuals and keys are available
to aid in proper identification [6,61,75,91].