Also known as the honey mesquite is a small to medium, thorny shrub and a tree in the legume family. It is native to the southwestern U.S. It grows extremely fast, has very dense shade, and produces a seed pod that is high in protein eaten by humans and animals. It is also readily available firewood since it thrives in a dry environment
The mesquite has rounded big and floppy drooping branches with feathery foliage. It usually grows 20-30 feet but can grow as tall as 50 feet. It flowers from March to November with pale, yellow elongated spikes and bears straight, yellow seed pods. Every mesquite has a radial and tap root system that helps it endure the desert.
Honey mesquite provides cover for large wildlife species and shade for livestock. Its invasion of grasslands has greatly increased the amount of habitat for white-tailed deer and other brush-dependent wildlife species [114,120,165,174]. Honey mesquite-blackbrush acacia and honey mesquite-sand live oak (Quercus virginiana var. geminata) savannas of southern Texas provide important habitat for the collared peccary. Collared peccaries often bed down in dense mesquite thickets [51]. The banner-tailed kangaroo rat frequently digs burrows under mesquite shrubs [112].
Honey mesquite shrublands provide important habitat for numerous species of birds. A search of 1,600 woody plants on the Rolling Plains of central Texas found that nesting nongame birds preferred lotebush and honey mesquite over all other woody plants [139]. A partial list of birds known to breed in mesquite communities include the pyrrhuloxia, phainopepla, Abert's towhee, northern cardinal, Chihuahuan raven, white-necked raven, scaled quail, Gambel's quail, northern bobwhite, burrowing owl, northern mockingbird, loggerhead shrike, cactus wren, lark bunting, mourning dove, black-throated sparrow, Swainson's hawk, Harris hawk, roadrunner, scissor-tailed flycatcher, ash-throated flycatcher, and the northern oriole [45,139,164,176]. The Swainson's hawk, Harris hawk, roadrunner, scissor-tailed flycatcher, ash-throated flycatcher, northern cardinal, white-necked raven, cactus wren, loggerhead shrike, northern oriole, pyrrhuloxia, northern mockingbird, and mourning dove all nest in honey mesquite plants [45,164]. Honey mesquite provides cover for many types of quail during hot weather; quails preferred lotebush cover during cold weather [36,140]. On the Rolling Plains of Texas, northern bobwhite coveys often feed within the security of dense honey mesquite stands and prefer honey mesquite for nest building [176]. Large honey mesquite provide roosts for migratory songbirds, wild turkeys, and resident owls, and provide hunting perches for raptors [139].
Honey mesquite stands along the Rio Grande serve as a corridor for migratory birds. At least 38 species of birds nest within honey mesquite dominated Rio Grande riparian communities [162]. Cavity-nesting birds often excavate in large western honey mesquite trees [123]. In marshes along the Colorado River in southern California, western honey mesquite snags provide nesting sites for herons and cormorants and sometimes serve as major rookeries [5].
Honey mesquite is a deciduous, thorny shrub or small tree exhibiting a high degree of variation in growth form. The three most common forms are: 1) a single-stemmed tree reaching 20 to 40 feet (6-12 m) in height, with crooked, drooping branches, 2) an erect, multiple-stemmed bush or small tree, often 10 to 15 feet (3-4.6 m) tall, and 3) a decumbent or running bush found on deep sandy soils [64,125,130]. The largest trees are often found along water courses or floodplains where the deep root system has access to year-round water [115]. All mesquites have a strong tendency for apical dominance and a well-developed crown [129]. Undisturbed trees therefore develop into single-stemmed trees. If the aboveground growth is damaged or removed, such as by freezing weather, drought, fire, trampling, browsing, cutting, or herbicide treatment, dormant buds located on the underground stem initiate new growth, resulting in the many-stemmed growth form [61]. On the Rolling Plains of north-central Texas, 27 year-old plants within a fenced exclosure ranged from 0.7 to 4.9 feet (0.2-1.5 m) tall [155]. Thus small plants that are decades old may be mistaken for seedlings. Thorns may be 1 to over 2 inches (2.5-5 cm) long and generally occur singly on young branches [75]. The flowers are in a raceme [178]. The flattened, straight, or curved legume-type pods are 4 to 8 inches (10-20 cm) long and occur in drooping clusters [178]. The seeds are oval, 0.2 inch (5 mm) wide, 0.28 inch (7 mm) long, and 0.08 inch (2 mm) thick [125].
Honey mesquite's root system is well adapted to dry climates (during and shortly after seedling establishment, the rate of root growth exceeds that of shoot growth [163]). Honey mesquite is a facultative phreatophyte which extracts moisture from a large volume of soil through a well-developed root system [8,81,171]. Honey mesquite's taproot commonly reaches depths of 40 feet (12 m) when subsurface water is available [63], though a taproot 190 feet (58 m) deep has been observed [163]. In areas where the soil is shallow, where water does not penetrate deeply, or where a distinct calcium carbonate layer is present, the taproot seldom extends more than 3 to 6 feet (1-2 m), and an extensive system of lateral roots often extends up to 60 feet (18 m) away from the plant base [9,43,64,81,163]. Lateral roots of a 19.7 foot (6 m) tall honey mesquite tree excavated on the Rolling Plains of north-central Texas were concentrated in the upper 1 foot (0.3 m) of the soil profile [81]. Similarly, Sosebee and Dahl [162] reported that most active lateral roots are in the upper 2.5 feet (0.75 m) of soil. Sprouting from lateral roots is common [81]. These adaptations allow honey mesquite to retain most leaves in all but the most severe droughts.
As a legume, honey mesquite is capable of housing N2-fixing bacteria in nodes along its roots; it is also commonly heavily colonized by arbuscular mycorrhizal fungi [14]. Mesquites obtain about half of their nitrogen from symbiotic bacteria housed in root nodules [108]. Deloach [47] commented that nodes are rarely seen in honey mesquite but that the nodulation process is likely under multifactorial control and may not always be observable. Rundel [148] found that in the Sonora Desert of California, honey mesquite may fix up to 66 lbs/ acre/ year. An nitrate accretion rate of 90 lbs/ acre/ year was observed for 10 years in California below a western honey mesquite stand [67]. Honey mesquite, though potentially detrimental to competitive grasses, also facilitates plant growth by increasing soil organic matter content and nitrogen status [7,16].
Maximum ages that plants attain is unclear. Near Amarillo, Texas, the maximum age of plants within a stand of multi-stemmed honey mesquites ranged from 40 to 110 years [64]. On the Rio Grande Plains of Texas, Archer [12,13] found that 89% to 93% of honey mesquite plants were less than 100 years old, and the maximum age of plants sampled was 172 to 217 years.
Honey mesquite is distributed from California east to Kansas and south to Louisiana, Nuevo Leon, and Baja California [92,101,111,116]. The PLANTS database provides a map of honey mesquite's distribution in the United States.
The typical variety of honey mesquite is distributed from southwestern Kansas, western Oklahoma, and Louisiana, and most of Texas west to New Mexico and south to Tamaulipas, Nuevo Leon, and Coahuila, Mexico [74,101,116]. Western honey mesquite occurs in western Texas, southern New Mexico, southeastern and western Arizona, extreme southwestern Utah, southern Nevada, southern California, and northern Mexico [92,111]. Prosopis glandulosa var. prostrata occurs in Texas [101].
Before the introduction of livestock by European settlers, the geographic ranges of North American mesquites were probably more distinct. Since livestock effectively disperse the seeds, mesquites have increased their abundance across the Southwest since settlement times, and many species' ranges have changed [92,100]. The ranges of the typical variety of honey mesquite and western honey mesquite overlap in western Texas, eastern New Mexico, and northeastern Mexico [139], but for the most part honey mesquite occurs east of the Pecos River, while western honey mesquite is more prevalent west of the Pecos River [91,95]. Along the Rio Grande River near El Paso, Texas, honey mesquite, western honey mesquite, and velvet mesquite all occur together [20]. Western honey mesquite is the most common mesquite in the Trans-Pecos Region of Texas [137]. Isolated populations of the typical variety occur in southeastern Arizona, southern California, and near Shreveport Louisiana, all thought to be introductions, possibly from livestock-dispersed seed along railways or stage routes, or by other human introductions [20,91,92,95]. Similar isolated populations of western honey mesquite occur in the San Joaquin Valley, California [21,89].
Fire adaptations: When the aboveground portion of honey mesquite is damage by fire, regeneration occurs by sprouting from lateral roots in the upper 1 foot (0.3 m) of soil and establishing from seed [81]. Mature plants contain numerous, dormant buds on the upper 12 inches (30 cm) of the taproots [47,62,64] where they are insulated from the heat of most fires. Following top-kill by fire, numerous sprouts arise from the underground buds. Even 6- month- old seedlings have sufficiently developed underground stem buds to allow plants to survive "cool" burns [190]. The data of Ansley and others [10] suggest that bark on older stems is often thick enough to protect the phloem from damage; when top-kill does occur, it is more commonly via damage at canopy height. Mortality is low in honey mesquite, particularly in lowland areas where root systems are well developed [188,190]. In riparian communities of the Colorado River, however, where western honey mesquite grows with saltcedar, frequent fire will likely lead to a decline of western honey mesquite and increase of saltcedar because the latter grows much faster [4,126].
Numerous wild and domestic animals consume and disperse honey mesquite seed [104]. Little is known about honey mesquite seed banks, seed longevity in the field, or the importance of seed banks in recovery after fire [171]. Seed from off-site honey mesquite could potentially be transported to burned areas by animals. Johnston [97] states that where mesquite dominates brushy ranges, the successional changes may not have been from mesquite-free grasslands to brushlands, but from low stature mesquite grasslands to brushlands. Brown and Archer [33] hypothesize that since mesquites evolved with browsing Pleistocene megafauna, low densities of honey mesquite in southwestern grasslands prior to European-American introduction of livestock resulted primarily from limited seed dispersal after the Pleistocene [129].
FIRE REGIMES: More is known about historic FIRE REGIMES in communities of the typical variety of honey mesquite than in western honey mesquite communities. Western honey mesquite occurs in the Mojave and Sonora deserts; not much is known of their fire histories. It is assumed that fuels in these desert were so discontinuous in the past that fire was infrequent [121]. In former desert grassland communities that honey mesquite has invaded in southeastern Arizona, southern New Mexico, and southwestern Texas, fires occurred at "rather frequent intervals" prior to livestock introduction [90]. McPherson [121] states that it is difficult to know detailed fire history in desert grasslands but indirect evidence, primarily accounts of European- American settlers, suggests that fires occurred at least every 10 years. Also, based on known rates of velvet mesquite establishment and growth in grasslands, McPherson [121] concluded that fires had to have occurred at 7 to 10 year intervals to prevent its establishment. Using a similar analysis, Paysen and others [135] concluded that the likely historic average fire return interval in mesquite savannas was 10 years. There were large numbers of livestock in some areas of the desert grassland as early as 1880, and fire frequency was reduced due to lack of fuel rather than fire suppression [90].
Honey mesquite also grows in dune fields that, because of low fuel loading, have seldom if ever burned. An example of such a habitat is the Wild Horse Desert of southern Texas, a sandy rangeland where fuel is discontinuous and honey mesquite grows 15 to 20 feet (4.6-6.1 m) tall [90].
Fire return intervals for plant communities and ecosystems in which honey mesquite occurs are presented below. Find further 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".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium < 10 [106,135] bluestem-Sacahuista prairie A. littoralis-Spartina spartinae < 10 desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 plains grasslands Bouteloua spp. < 35 blue grama-tobosa prairie B. gracilis-Pleuraphis mutica < 35 to < 100 paloverde-cactus shrub Cercidium microphyllum/Opuntia spp. < 35 to < 100 blackbrush Coleogyne ramosissima < 35 to < 100 juniper-oak savanna Juniperus ashei-Quercus virginiana < 35 Ashe juniper J. ashei < 35 Ceniza shrub Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa < 35 galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea < 35 to < 100 [135] mesquite Prosopis glandulosa < 35 to < 100 [121,135] mesquite-buffalo grass Prosopis g.-Buchloe dactyloides < 35 Texas savanna Prosopis g. var. glandulosa < 10 shinnery Quercus mohriana < 35 little bluestem-grama prairie Schizachyrium scoparium-Bouteloua spp. < 35 [135]Prescribed burning has not been effective in controlling honey mesquite because of the species' fire survival strategies. However, plants that have been recently top-killed by fire, drought, or herbicides are more susceptible to fire mortality [187]. Fire has been used to kill up to 27% of large mesquite trees previously top-killed with herbicide [30,31]. Fire has also been used to fell standing dead stems of herbicide-treated mesquites [30]. On grasslands in good condition with low densities of honey mesquite, repeated prescribed fires may keep honey mesquite low in stature but will probably kill only a few seedlings [121].
On some sites honey mesquite has reduced the native grass cover to the extent that there is now insufficient fuel to carry anything more than a "spotty" or "cool" fire [61]. In general, fire will not carry in southwestern grasslands unless there is a minimum of 600 pounds per acre (654 kg/ha) of herbaceous fuels. When there is less than 892 pounds per acre (1,000 kg/ha), a wind speed of 8 miles per hour (12.8 km/hr) is needed to carry the fire [189].
Once honey mesquite stands are established, use of stand- replacement fires can cause only minimal reduction in honey mesquite density; regrowth is both rapid and of a thicket-like structure, that is commonly more detrimental to forage production than the pre-burn stand structure [7]. Paysen and others [135] recommend that managers use low-severity fires so that apical dominance is maintained and sprouting is minimized. Ansley and others [7] also support this strategy and recommend winter fires instead of summer fires except when fuel loads are low. The Texas Extension Service recommends the following conditions for prescribed burning (in intervals of 5 to 10 years) in honey mesquite-tobosagrass communities: wind of 6 to 15 mph (10-25 kph), relative humidity between 20% and 60%, temperature between 45 and 70 degrees Fahrenheit (7.2- 21 °C), during late January, February, or early March [2].
It is well-documented that fire can be used as a management tool in tobosagrass and other mesic honey mesquite habitats [2,7,135]. In shortgrass communities, according to Wright [186], fire cannot be "recommended as a tool to control shrubs or increase grass production." In these communities fire, particularly in dry years, can harm black grama and other grasses, thereby increasing the competitive ability of western honey mesquite [37,61,186].
Interactions of fire and herbicide effects: Britton and Wright [30] observed 24% mortality in a stand of honey mesquite (20 miles south of Colorado City, Texas) that had been top-killed by herbicides 4 years prior to burning. On the Rolling Plains of Texas, 32% of honey mesquite were killed by fires occurring in March or April soon after a 2,4,5-T herbicide treatment. These mortality rates were unusually high and were attributed to dead foliage and stems that increased fire severity locally. Repeated winter or summer fires did not achieve root-kill greater than 4%. Though there had been an herbicide (2,4,5-T) treatment 17 to 26 years prior to the fire, there were not many dead stems to increase fire intensity and whole-plant mortality [190]. Three to six foot tall (1-2 m) honey mesquite plants, which had survived herbicide (2,4,5-T) spraying 7 years earlier, were top-killed by a late March prescribed fire in western Texas. Most plants survived by sprouting from belowground buds. Resprouts ranged from a few inches to over 4 feet (1.2 m) tall 6 months after the fire [80]. See the Research Project Summary of this study for additional details.
Following controlled spring burning of honey mesquite plants in southwestern Texas that had survived application of 2,4,5-T 4 years earlier, honey mesquite plants were top-killed. Resprouts grew 17 inches (43.2 cm) tall within 4 months [132]. Six years of postfire growth is summarized below; data are means of 15 replicates:
Postfire year Height of resprouts (inches) Resprouts per plant 1 17.0 14.0 2 29.1 8.4 3 30.5 9.0 4 41.6 6.1 5 36.1 4.8 6 53.7 5.5Another study of fire effects on honey mesquite was undertaken in the High Plains of Texas near Colorado City. Fire was prescribed on upland and riparian areas. The season during which fire occurred was not specified but honey mesquite were physiologically active at the time. On bottom lands there was no mortality of large honey mesquite even though they had been sprayed with herbicides (2,4,5-T); well-developed root systems allowed resprouting the following growing season. On upland sites mortality was up to 50%. Percent mortality was measured up to 5 years after burning, showing that fire-induced mortality is sometimes not immediate. Insect and rodent damage following fire damage causes indirect fire morality. Results and burning conditions were as follows [190].
Year of burn Number of trees surveyedMortality
Tobosa fuel Fuel moisture Air temperature Relative humidity Wind speed 1st year 2nd year 3rd year 4th year 5th year (lbs/acre) (%) (°F) (%) (mph) 1968 50 32 32 32 32 32 7,000 19.8 80 25 10 1969 250 8 13 18 20 22 5,000 19.2 67 45 45 1969 950 11 19 24 27 28 5,700 15.8 72 38 13 1970 50 12 12 18 ---- ---- 4,000 15.0 70 23 12 1971 60 12 15 15 ---- ---- 4,800 19.5 60 54 5 1971 60 45 50 50 ---- ---- 4,200 14.7 80 32 10Honey mesquite grows on a wide variety of sites and soil types in the Chihuahuan Desert and southern Great Plains. Honey mesquite was less common and more restricted to drainages prior to European-American settlement and livestock introduction. It has invaded grasslands as a result of overgrazing and reduced fire frequency [50]. On upland sites it often invades grasslands where it forms shrubby thickets. On some sites it occurs as scattered plants forming mesquite savannas, but on others its persistence has led to many grasslands being converted to "brushy ranges" or thorny scrublands [12,13,151]. Johnston [98] describes the "plains" of southern Texas as being covered by more or less dense growths of shrubs and low trees. Density of mature plants can range from 50 to over 1,500 plants per acre (124-3,716/ ha.) [62]. Up to 3,000 seedlings per acre (7,500/ ha.) have been observed in northern Texas [156].
In the Mojave and Sonoran deserts, rainfall is generally insufficient to provide adequate surface soil moisture for western honey mesquite to survive. Under these extremely arid conditions, western honey mesquite is a phreatophyte, typically occupying alkali sinks, outwash plains, dry lakes, oases, arroyos, or riverbanks, where plants have access to permanent underground water [96,158]. Plants are much less common outside washes [102].
Soils: Mesquites are adapted to most soil types, but in Texas, honey mesquite tends to grow best on medium to fine-textured soils. In areas of western Texas and southern New Mexico, honey mesquite grows on hummocky sand dunes [44]. Honey mesquite can grow rapidly to keep photosynthetic and reproductive structures above rising sand level [110]. On the Jornada Experimental Range near Las Cruces, New Mexico, honey mesquite is found on all soil types including loamy sand, sandy loam, calcareous silt loam, noncalcareous silt loam, gravelly sand loam, deep sandy loam, and calcareous clay [37].
Elevation: Honey mesquite generally grows below 4,500 feet (1,387 m) in elevation [64]. Western honey mesquite's elevational range in California is from 197 feet (60 m) below sea level to 3,575 feet (1,090 m) above sea level [88]; in Utah western honey mesquite grows between 2,197 feet (670 m) and 3,838 feet (1,170 m) [181]. In Arizona, western honey mesquite grows primarily below 5,000 feet (1500 m) [102]. In New Mexico, the typical variety of honey mesquite grows primarily between 3,000 and 5,000 feet (900-1500 m) [116].
Climate: In arid areas where annual rainfall is less than 6 inches (150 mm), honey mesquite is typically found along drainageways. It appears to be best adapted to uplands where annual rainfall reaches 15 to 20 inches (380-510 mm) and may be found on sites where annual rainfall exceeds 30 inches (760 mm) [151]. Honey mesquite is restricted northward and is limited to where the average annual minimum temperature is above -5 degrees Fahrenheit (-20 °C) and the frost-free growing season is 200 days or more [64].
Fire mortality is usually low in honey mesquite. Following most range fires, honey mesquite is top-killed and then resprouts. Near Vernon, Texas winter fires top-killed 72% of honey mesquite and reduced their canopy by 95% but did not cause any whole-plant mortality. Honey mesquite in a honey mesquite/ tobosagrass savanna in western Texas was 90% top-killed and had 10% whole-plant mortality. Honey mesquite in silver bluestem, red threeawn (Aristida longiseta), buffalograss, vine mesquite, plains bristle grass, and sand dropseed grassland in western Texas experienced 76% top-kill and 11% mortality. In southern Texas, in an acacia (Acacia spp.), buffalograss, plains bristle grass community, honey mesquite had 72% top-kill and 10% mortality after a late summer fire. Of the herbaceous vegetation on burned and unburned sites, there was little difference in basal density, species composition, or number of dead plants [29].
There are conflicting findings regarding the relative impacts of fuels and weather conditions on honey mesquite damage by fire. At the Wagoner Estate near Vernon, Texas, Ansley and Lucia [6] compared 2 plots: plot 1 had 4,085 lbs/ac of fine fuel and plot 2 had 1,861 lbs/ac of fine fuel. On plot 1, 72% of honey mesquite was top-killed and there was a 95% reduction in total canopy; on plot 2, honey mesquite was 15% top-killed and its total canopy cover was reduced 42%.
The influence of mesquite size and fuel loading on fire mortality of velvet mesquite, a closely related species, has been thoroughly studied [41,69,141]. Following a June fire on the Santa Rita Experimental Range in Arizona, velvet mesquite suffered 25% mortality in an area with 4,480 pounds per acre of herbaceous fuel dominated by the exotic Lehman lovegrass (Eragrostis lehmanniana), but in areas with 2,200 pounds per acre of herbaceous fuel dominated by black grama, velvet mesquite suffered only 8% mortality [41]. Prescribed burning on the Santa Rita Experimental Range generally resulted in about 50% mortality of young velvet mesquite that were less than 0.5 inch (1.25 cm) in basal stem diameter, but only 8% to 15% mortality of plants that were greater than 0.5 inch (1.25 cm) in basal diameter [69]. One experimental burn on the Wagoner Estate near Vernon, Texas showed that honey mesquite top-kill was more correlated with relative humidity and air temperature than with amounts of total or fine fuel [11]. Another detailed fire study was undertaken on the Welder Wildlife Refuge of southern Texas. Fire peak temperature and temperature duration at canopy level were found to influence mesquite top-kill more than extreme temperatures at the ground level [10].
Using a propane burner and temperature control to simulate natural fire, Wright and others [190] found that young honey mesquite plants are very susceptible to "moderate- severity" fires until they reach 1.5 years of age, moderately susceptible at 2.5 years, and very tolerant after 3.5 years. In the study, the percent mortality (after 15 months) of various ages of individually burned young honey mesquite plants was observed after 15 months after exposure; results are summarized below :
Age Temperature (°F) 220 435 780 1,115 control (years) Mortality (%) 0.5 43 91 100 100 14 1.5 60 100 100 100 0 2.5 20 40 64 72 0 3.5 8 8 8 8 4 10 (approx.) 0 0 4 8 0The fruit of honey mesquite is valuable forage for livestock and wildlife. Cattle, horses, domestic sheep and goats, mules, and burros eat large quantities of the ripe fruit during summer and fall [43,64]. Livestock often remove the fruit as high on the tree as they can reach and eat fallen pods from the ground [18]. Though seeds are high in protein little is digested and many pass through livestock digestive tracts intact and viable [64]. Livestock do not consume the foliage to any great extent [115]. Foliage consumption is high only during drought years, especially in the early spring when other forage is sparse [43,68,100]. Most livestock consume mesquite (Prosopis spp.) flowers when available [115]. In some areas of Mexico, mesquite beans are collected, ground, and fed to cattle [48]. Because of its abundance in Texas, honey mesquite wood has been proposed as a roughage source for ruminants. Preliminary research indicates that cattle weight gains are satisfactory when ozone or sulfur dioxide is used to increase cellulose digestibility of honey mesquite woodchips used as supplemental feed [36,143].
The fruit crop of honey mesquite is quite predictable, annually providing an abundant and nutritious food source for numerous wildlife species upon ripening in July and August [103]. Honey mesquite seeds form an important part of the diet of mice, kangaroo rats, woodrats, chipmunks, ground squirrels, rock squirrels, cottontail, skunks, quail, doves, ravens, the black-tailed prairie dog, black-tailed jackrabbit, porcupine, raccoon, coyote, collared peccary, white-tailed deer, mule deer, wild turkey, and mallard [1,23,43,73,176,177,179]. Many species of small rodents derive a large portion of their diet from mesquite seeds [1,48]. On the Jornada Experimental Range, these animals frequently store whole beans of western honey mesquite in dens or caches. Honey mesquite beans formed the bulk of stored food [185]. Mesquite flowers are eaten by numerous bird species [160]. Many species of quail eat mesquite buds and flowers in the spring, and seeds during the fall and winter [176]. Mesquite seeds often comprise 10 to 25% of the Gambel's and scaled quails' diets [46,48]. In a southwestern Texas study, honey mesquite fruit comprised 14.9% of the white-tailed deer summer diet, but deer use of any honey mesquite parts during the rest of the year was minimal [177].
Mesquite browse is generally not a very important wildlife food source. Wild turkeys, round-tailed ground squirrels, cottontails, and woodrats consume some leaves [23,73]. Jackrabbits consume large amounts of honey mesquite. In southwestern Texas, honey mesquite (primarily leaves) comprised 11% and 19.9% of black-tailed jackrabbit diet during winter and spring [177]. On the Jornada Experimental Range near Las Cruces, New Mexico, jackrabbits often crop honey mesquite leaves, buds, and bark as high as they can reach [180]. In this study, honey mesquite was 56% of the black-tailed jackrabbit diet. Locally, mule deer consume large quantities of honey mesquite foliage, but this may reflect a scarcity of other browse rather than a preference for honey mesquite [157].
Along the lower Colorado River on the border of southern California, western honey mesquite is often infested with mesquite mistletoe (Phoradendron californicum). Western honey mesquite communities often attract large numbers of birds that feed on mistletoe fruit [157].
Coastal prairies of southeastern Texas: Associated brush species include acacias (Acacia spp.),
lime pricklyash (Zanthoxylum fagara), lotebush (Ziziphus obtusifolia), huisache
(Acacia farnesiana), bluewood (Condalia hookeri), and narrowleaf forestiera (Forestiera
angustifolia). Common grass associates include little bluestem (Schizachyrium
scoparium), plains bristle grass (Setaria macrostachya), big
bluestem (Andropogon gerardii var. gerardii), indiangrass (Sorghastrum
nutans), and switchgrass (Panicum virgatum) [27,73,153]. On coastal prairies of the Welder
Wildlife Refuge, honey mesquite grows with acacia species, tussock grass (Nassella
leucotricha), dropseed grasses (Sporobolus spp.), and silver bluestem
(Bothriochloa laguriodes) [79].
Rio Grande Plains of southwestern Texas: Honey
mesquite is often codominant with mixed-brush species like huisachillo (Acacia
tortuosa), blackbrush acacia (Acacia rigidula), guajillo (Acacia berlandieri),
spiny hackberry (Celtis pallida), lotebush, desert yaupon (Schaefferia
cuneifolia), lime pricklyash, Texas persimmon (Diospyros texana),
and bluewood. Common grasses include little bluestem, Texas grama (Bouteloua
rigidiseta), yellow foxtail (Setaria geniculata), bristle
grass (Setaria spp.), hooded windmill grass (Chloris cucullata), thin paspalum
(Paspalum setaceum), and buffalograss (Buchloe dactyloides)
[13,28,71,85,151]. Brown [32]
describes communities in small basins in the Rio Grande area where honey mesquite,
longleaf ephedra (Ephedra trifurca), and soaptree yucca (Yucca elata) are
the dominant shrubs and the understory is composed of buffalograss and dropseed
grasses.
These communities are frequently located around the edge of ancient lake beds.
Western Texas and New Mexico: Honey mesquite and
western honey mesquite are
often associated with more xeric species, including allthorn (Koeberlimia
spinosa), Gregg catclaw (Acacia greggii), fourwing saltbush (Atriplex
canescens), tarbush (Flourensia cernua), and catclaw mimosa (Mimosa
biuncifera). Associated grasses include black grama (Bouteloua
eriopoda), sideoats grama (B. curtipendula), mesa dropseed (Sporobolus
flexuosus), threeawns (Aristida spp.), burro grass (Scleropogon
brevifolius), tobosagrass (Pleuraphis mutica), and curlymesquite (Hilaria
belangeri) [37,85,151].
East-central Texas: Honey mesquite is often found
in post oak (Quercus stellata) savannas. Common associates in these
savannas include blackjack oak (Q. marilandica), water oak (Q. nigra),
sugarberry (Celtis laevigata), honey-locust (Gleditsia triacanthos),
hawthorn (Crataegus spp.), common persimmon (Diospyros virginiana),
eastern redcedar (Juniperus virginiana), gum bumelia (Bumelia
lanuginosa), skunkbush sumac (Rhus trilobata), and winged elm (Ulmus
alata) [151].
Spring bud break in honey mesquite can vary by as much as 6 weeks from year to year. Bud break is dependent upon both photo- and thermal periods and rarely occurs until after the last spring frost has passed or the photoperiod exceeds 11.5 hours [43,163]. Honey mesquite apparently has a cold requirement that must be met before bud burst occurs. Goen and Dahl [70] found that the higher the number of consecutive days with minimum temperatures below 30 degrees Fahrenheit (-1 °C) during January 15 to February 14, the earlier spring bud break occurs. They give equations for predicting honey mesquite bud break based on minimum winter temperatures. Other researchers state that honey mesquite bud burst begins in the spring when the soil warms to 64 degrees Fahrenheit (18 °C) [124]. Plants from northern populations generally exhibit later bud burst than plants from southern populations [120].
Following bud burst, twig elongation and leaf growth are rapid and generally completed in about 6 weeks [43]. New foliage is generally very dense following a wet spring and fall, but less foliage is produced if the preceding spring and fall were dry [163]. Inflorescences emerge in the spring with the leaves. By the time the leaves are fully expanded, miniature fruit pods have begun to develop [43]. It takes 2 to 3 months for the fruits to mature, and by late summer they fall from the plant. More than 1 fruit crop per year is possible but uncommon. Sometimes a wet period late in the flowering season causes a flush of new growth, producing new leaves and flowers and, consequently, a 2nd fruit crop. Flowering may occur up to 4 times in 1 growing season. Flower production varies with amount of available soil moisture. Heavy flowering and fruiting often occur when soil moisture is low; high soil moisture at the time of flowering appears to suppress fruit production [129].
Leaf drop generally occurs in November or December and is often initiated by a killing frost or leaf removal by insects [43]. Plants from northern populations show early dormancy and are more resistant to freezing damage than plants from southern populations [134]. Seasonal development of honey mesquite plants in western Texas was documented as follows [182]:
Date Phenological state November to March trees dormant April 16 most trees beginning to leaf out; immature flower spikes less than 1 inch (2.5 cm) long May 10 trees with fully developed leaves, white flowers, and immature flower spikes May 24 few flowers remaining; immature (green) flower spikes still present on many trees; green pods less than 1 inch (2.5 cm) long June 7 pods vary in length from 2 to 6 inches (2.5-15.2 cm) July 5 pods maturing (seeds partially developed) August 26 pods fallen from tree September and October trees with leaves, but physiologically inactiveThe response of honey mesquite following fire depends on the amount of damage the fire inflicted on the plant. Plants may initiate new growth from either buds within the crown or from underground buds on the taproot or lateral roots [73] following fire. Following low-severity fires which only partially top-kill plants, mesquites often sprout from axillary buds on branches [41]. In a low fuel load (1160 lbs/ac) fire near Encinal, Texas honey mesquite had recovered to 106% of preburn canopy cover in 2 years, but still had 14% less canopy cover than honey mesquite in the unburned control plot [78]. Following fires that result in complete top-kill, plants may survive by producing numerous basal stem sprouts, by establishing from seed, or by sprouting from lateral roots or the upper part of the taproot [47,62,64].
Winter burns often allow regrowth from buds in the crown because fire severity is not great enough to cause complete top-kill. Though percent canopy cover of honey mesquite recovers quickly following these low-severity fires, stand structure becomes more like a savanna than a thicket, which is the most common structure following a disturbance that causes a high rate of complete top-kill [7].
Breeding system: Honey mesquite flowers have both pistils and stamens [150].
Pollination: As is typical of insect-pollinated plants, honey mesquite flowers develop simultaneously with the leaves, are high in nectar, and are scented. Honey mesquite is pollinated primarily by bees. At least 160 species of bees are associated with mesquites in the American Southwest. Although mesquite inflorescences contain hundreds of flowers, only a few fruits develop per inflorescence. Most flowers are pollinated by numerous insect visitors, but self abortion prevents most ovules from maturing. This ensures that adequate resources are available for the fruits that do develop [160].
Seed production: Honey mesquite plants generally produce seed by 3 years of age [75]. Several seeds are encased within an indehiscent fruit. The reproductive potential of honey mesquite is often greatly reduced by seed-feeding insects, but honey mesquite produces pods in such abundance that numerous viable seeds are still produced [103]. Insects using flowers (leaf-footed bugs and thrips) reduced pod production from a mean of 131 pods per tree on insecticide-sprayed trees to 97 pods per tree on unsprayed trees in western Texas. Bruchid beetles (weevils) are dependent on mesquite pods. In a southern California study, western honey mesquite had an average of 12 seeds per pod, of which an average of 5 were destroyed by bruchid beetles [133].
Seed dispersal: Pods are eaten and then dispersed by domestic and wild animals. When honey mesquite pods were fed to livestock, 97%, 79%, and 16% of the seeds passed through the digestive tracts of horses, yearling steers, and ewes, respectively, with the greatest number of seeds passing through between 42 and 60 hours after consumption [64]. In southern Texas, Brown and Archer [33] found honey mesquite seedlings in 75% of cattle dung piles sampled in September, but no seedlings on sites fenced to exclude cattle. On sites without cattle, no seeds were found away from parent trees. Because it takes days for seeds to pass through the digestive tracts of domestic animals, seeds are dispersed great distances. Mesquite seedlings commonly germinate from uneaten seeds in rodent caches. Floods are also a common means of seed dispersal [69].
Seed banking: Most seeds of a closely related species, velvet mesquite, germinated within 3 years after pod segments were buried 1 inch (2.5 cm) below the soil surface of an Arizona site. About 35%, 9%, and 1% of germination occurred 1, 2, and 3 years after planting. Honey mesquite seeds in dry storage can remain viable for decades. Sixty percent viability was reported for 44-year-old velvet mesquite seeds taken from herbarium specimens [171].
Germination: Honey mesquite seeds contain a protective endocarp. Scarification of this hard seed coat must occur before the seed can germinate. Scarification 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 or fire [75]. Under laboratory conditions, scarified honey mesquite seeds placed on moistened filter paper germinated in about 7 hours at 93 degrees Fahrenheit (33 °C) [154].
Seedling establishment/growth: Honey mesquite seeds must be covered with a small amount of soil or dung for seedlings to establish. Seeds that germinate on the soil surface usually die. When honey mesquite seeds were planted at various soil depths, emergence rates were greatest for seeds planted between 0.2 and 0.6 inch (0.5-1.5 cm) from the soil surface. No seedlings emerged when seeds were planted more than 2 inches (5 cm) deep [154]. Field studies in southern Texas found that under natural conditions honey mesquite seedlings emerged from dung both fall and spring following peaks in rainfall. When honey mesquite pods were fed to livestock 82%, 69%, and 25% of the seeds that passed through the digestive tracts of horses, yearling steers, and ewes, respectively, germinated [64]. Kramp and others [104] tested the effect of coyote, cow, and deer scat on 1- year seedling survival. Ten percent survived in coyote and cow manure, 31% survived in deer scat, but there was a much higher average number of initial seedlings in cattle manure (7 per manure unit) than in coyote and deer scat (3 per unit). Kramp and others [105] found that 27% of seedlings survived 1 year in clipped plots compared to 9.4% in unclipped plots (p=0.14). In central Texas, establishment of honey mesquite seedlings from sown seed was high under several different clipping regimes on both grazed and protected areas. However, on grasslands protected from grazing for several years, seedling establishment was 7 to 8 times greater when the grasses were clipped monthly to 10 inches (25 cm) than when not clipped [34]. Dense grass cover can reduce honey mesquite seedling establishment because seedlings emerge and establish with a 50% reduction in solar radiation, but when solar radiation is reduced by 75%, survival of seedlings is reduced [152].
Asexual regeneration: Honey mesquite plants can sprout from numerous perennial dormant buds located along rhizomes or the upper part of the root [62,64]. Dormant buds can occur up to 12 inches (30 cm) below the soil surface on older trees but are most commonly concentrated along the basal portion of the underground stem in a zone 2 to 6 inches (5-15 cm) below the soil surface [62]. When aboveground growth is damaged or killed, new sprouts arise from the bud zone. If aboveground growth is destroyed or damaged during a dormant period, sprouts arise the following spring and often flower during their first growing season. If aboveground growth is damaged during the wet part of the growing season when root carbohydrate levels are high, plants resprout rapidly but do not flower until the following growing season. If destroyed during the dry portion of the growing season when root carbohydrate levels are low, sprouting is delayed or slow, sometimes for 3 to 5 years [163].
The successional pattern of grasslands that have become dominated by honey mesquite on the Rio Grande Plains of southern Texas has been from grassland to savanna to woodland. After colonizing grassland sites, a lone honey mesquite plant establishes a circular cluster of other woody plants within 10 to 15 years [33,34]. Honey mesquite apparently aids the establishment of other shrubs by attracting birds which disperse seeds of other woody species [24,33]. On study sites at the Texas Agricultural Experiment Station near Alice, Texas, a lone honey mesquite plant was found in 80% of all upland clusters of other shrubs. Woody plant clusters generally ranged from 3.3 to 132 feet (1-40 m) in diameter and contained 1 to 15 woody species. As new clusters are formed and old clusters expand and coalesce, a woodland is eventually formed. In about 25% of the clusters, the original lone honey mesquite had died. Death usually occurred before age 30 [33,34]. Invasion and establishment of honey mesquite in grasslands on the High Plains of western Texas facilitated the establishment of redberry juniper in much the same manner as described above [122]. Drought also appears to be a factor in the spread of honey mesquite. Honey mesquite seedlings often establish on areas where black grama cover has been reduced and gaps were created from the death of many plants following drought [37,61]. Western honey mesquite's deep root system increases its ability to compete with black grama on sandy soils during droughts [37].
The geographic range of honey mesquite has probably changed very little in the past 300 to 500 years, but the abundance of mesquite within this range has increased [50,98]. Some researchers state that range fires were very important in controlling honey mesquite before the introduction of cattle, while others believe that honey mesquite was rare on grasslands because of limited seed dispersal. Johnston [98] states that where mesquite has dominated former grasslands, it was probably originally present but stunted by repeated fire. Fire effects research supports this theory, demonstrating that honey mesquite is very fire tolerant when only 3 years old [190]. Plants may be top-killed by fire, but most resprout. Thus prior to grazing by livestock, repeated grassland fires probably only killed mesquite seedlings and a few other individuals but kept most plants low in stature and prevented many from producing seed.
Dispersal of mesquite seeds was likely greater during the Pleistocene when browsing megafauna, such as camelids, stegomastodons, notoungulates, and edentates were present [129]. With the introduction of livestock by European settlers, mesquite invaded grasslands as cattle transported seed from plants which were primarily found in draws and drainageways. Brown and Archer [33] state that seed dispersal was probably the most important factor in honey mesquite's increase. Reduced fire frequencies due to overgrazing would have allowed honey mesquite plants that were previously suppressed and kept low in stature to reach maturity and thus produce more seed for livestock to disperse away from the parent plants.
Fire exclusion has facilitated spread of honey mesquite. See the "Fire Ecology" section of this summary for further information.
In the Mesilla basin of southern New Mexico and northern Mexico there are extensive dune fields, some of which predate European-American settlement, and some that have been transformed from semidesert grasslands during this century. It is theorized that conversion to dunelands is a self-sustaining process which leads to further desertification [147]. With heavy grazing, drought, and competition with honey mesquite for soil moisture, much of the grass cover on these sandy sites was depleted. The loss of grass cover led to wind erosion and the formation of dunes around honey mesquite plants. The multi-stemmed growth form of honey mesquite, which characteristically occurs on sandy soils, entraps drifting sands [72,82].
The currently accepted scientific name of honey mesquite is Prosopis
glandulosa (Fabaceae) [50,181]. Three varieties are recognized [50]:
Prosopis glandulosa Torr. var. glandulosa honey mesquite
Prosopis glandulosa Torr. var. prostrata Burkart honey mesquite
Prosopis glandulosa Torr. var. torreyana (L. Benson) M.C. Johnston
western honey
mesquite
Little information is available regarding the ecology
of P. glandulosa var. prostrata. In this species summary,
"honey mesquite" refers to the species, while the "typical
variety" and "western honey mesquite" refer to Prosopis glandulosa var. glandulosa
and Prosopis glandulosa Torr.
var. torreyana, respectively.
Several hybrids have been reported [20,91,95]. Honey
mesquite ÃÂ western honey mesquite intermediates occur in western Texas and New
Mexico, and western honey mesquite × velvet mesquite (Prosopis
velutina) hybrids
occur in Arizona, Sonora, and Baja California [100].
Along the lower Colorado River in southern California, nursery- grown western honey mesquite seedlings have been planted with other native species to revegetate riparian areas following saltcedar removal [42,179]. The 'Tacna' (named for a site along the Gila River in Arizona) cultivar establishes quickly and resists psyllid (aphid-like insects) infestation. This accession was used in a riparian restoration project on the Gila River. Survival was greatest when seedlings were planted in holes that had been dug and refilled partway to reduce root impediments. The researchers also used a drip irrigation system and chicken wire cages to protect seedlings from jackrabbits and cottontails. The authors added that this cultivar, when used in dry areas like western Arizona, will not exacerbate range infestations with mesquite because the dry climate confines honey mesquite to drainages [146].
Stem cuttings of several species of mesquite have been successfully rooted in greenhouse experiments when treated with a rooting compound [59]. Members of the genus Prosopis are being developed for rehabilitation and biofuel production in developing countries to help alleviate firewood shortages, erosion, and other problems associated with desertification [57,58]. Because of their nitrogen fixation capability members of the Prosopis genus have potential to enhance soil quality [108,144].
Honey mesquite wood is used chiefly for firewood. The wood is easily sawed and split, is dry and heavy, ignites readily, and produces intense heat [76]. It is often the only fuelwood available in regions where it grows [178]. Since 1982, the use of honey mesquite wood in the barbeque industry has grown considerably in the United States [52]. Products made from honey mesquite include chips, chunks, nuggets, sticks, and charcoal briquettes [52,68]. Western honey mesquite's primary use is firewood, though locally it is also used for fenceposts and lumber. Charcoal is the main product of western honey mesquite in Mexico; a large proportion of this is exported to the United States [65].
There has been an increased interest in using honey mesquite wood in manufacturing furniture, flooring, and handcrafts. Manufacturers like the wood because it is easy to work with and has unique grain patterns that make the finished products attractive [109]. The wood is strong, hard, straight grained, warp proof, colored varying shades of orange and red, and has a low volumetric shrinkage (4-5%) [52,76]. However, few trees attain commercial size and many have serious defects which force craftsmen to pay high prices for mesquite lumber [52,134]. Fiberboard and chipboard have been made from honey mesquite but have not been marketed commercially [134].
Felker [56] states that with the current rate of use of long straight honey mesquite lumber, all of which comes from unmanaged stands, cannot be maintained without actively managing mesquite woodlands for the production of lumber. On more productive woodlands, mesquite thickets can be thinned to improve volume growth of some individuals while enhancing forage production for livestock.
Prosopis glandulosa, commonly known as honey mesquite,[4] is a species of small to medium-sized, thorny shrub[5] or tree in the legume family (Fabaceae).
The plant is primarily native to the Southwestern United States and Northern Mexico. Its range extends on the northeast through Texas and into southwestern Kansas and Oklahoma and northwestern Louisiana, and west to southern California.[3]
It can be part of the Mesquite Bosque plant association community in the Sonoran Desert ecoregion of California and Arizona (U.S.), and Sonora state (México), and in the Chihuahuan Desert of New Mexico and Texas in the US, and Chihuahua in Mexico.
Prosopis glandulosa has rounded big and floppy, drooping branches with feathery foliage and straight, paired spines on twigs. This tree normally reaches 20–30 ft (6.1–9.1 m), but can grow as tall as 50 ft (15 m). It is considered to have a medium growth rate.
It flowers from March to November, with pale, yellow, elongated spikes and bears straight, yellow seedpods. The seeds are eaten by a variety of animals, such as scaled quail. Other animals, including deer, collared peccaries, coyotes, cactus mice, and jackrabbits, feed on both pods and vegetation.[6]
Prosopis glandulosa has been intentionally introduced into at least a half-dozen countries, including Australia, Botswana, Namibia and South Africa.[9] The IUCN considers it as one of the world's 100 worst invasive species outside its native habitat range.[10][11]
The seeds are disseminated by livestock that graze on the sweet pods, and the shrubs can invade grasslands, with cattlemen regarding mesquites as range weeds to be eradicated.[12] Due to latent buds underground, permanent removal is difficult. Cutting them will only coppice them: A single-trunked tree that is cut down will soon be replaced by a multi-trunked version.[13]
Prosopis glandulosa shrubs and trees provide shelter and nest building material for wildlife, and produce seed pods in abundance containing beans that are a seasonal food for diverse birds and small mammal species.[5] As the common name indicates, honey mesquite is a honey plant that supports native pollinator species of bees and other insects, and cultivated honey bees.[12] It is a larval host for the long-tailed skipper and Reakirt's blue butterflies.
Mesquite flour is high in protein, low in carbohydrates, and can be used in recipes as a gluten-free substitute for wheat flour.
Within its native range in southwestern North America, its wood smoke is used to flavor meats when cooked over a mesquite fire. This is particularly popular in Texas in the US.
In Namibia, although an invasive species, it has qualities that have made it useful for humans, including: growing extremely rapidly there, having very dense shade, abundantly producing seed pods, and a readily available firewood.[14]
The indigenous peoples of California and southwestern North America used parts of Prosopis glandulosa as a medicinal plant, food source, building and tools material, and fuel.[15] The Cahuilla ate the blossoms and pods, which were ground into meal for cake.[16][17] The Pueblo peoples of New Mexico in the southwest United States use the seeds to produce mesquite flour for making traditional horno bread. The thorns of the plant were used as tattoo needles, and the ashes for tattoos, by the Cahuilla and Serrano Indians of Southern California.[5] Its dense and durable wood is prized for making tools and arrow points,[5] and for the unique flavor it lends to foods cooked over it. The deep taproots, often larger than the trunks, are dug up for firewood.
This species of mesquite, known as haas (pronounced [ʔaːs]) by the Seri people of northwestern Mexico, was very important for food and nonfood uses. The Seris had specific names for various stages of the growth of the mesquite pod.[18] Historically, it was a very important wild food plant because it fruits even during drought years.[19]
Prosopis glandulosa, commonly known as honey mesquite, is a species of small to medium-sized, thorny shrub or tree in the legume family (Fabaceae).
