SPECIES: Ungnadia speciosa
SPECIES: Ungnadia speciosa
AUTHORSHIP AND CITATION : Tirmenstein, D. A. 1990. Ungnadia speciosa. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ .
ABBREVIATION : UNGSPE SYNONYMS : NO-ENTRY SCS PLANT CODE : UNSP COMMON NAMES : Mexican buckeye Texas buckeye Texas-buckeye canyon buckeye Spanish buckeye New Mexican buckeye New Mexico buckeye false buckeye buckeye monillo monilla TAXONOMY : The currently accepted scientific name of Mexican buckeye is Ungnadia speciosa Endl. . Mexican buckeye is placed in the monotypic genus Ungnadia  within the family Sapindaceae . LIFE FORM : Tree, Shrub FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY
SPECIES: Ungnadia speciosa
DISTRIBUTION AND OCCURRENCE
GENERAL DISTRIBUTION : Mexican buckeye grows from the Edwards Plateau of south-central Texas west to Trans-Pecos Texas, and into southern New Mexico and northeastern Mexico . ECOSYSTEMS : FRES32 Texas savanna FRES33 Southwestern shrubsteppe FRES35 Pinyon - juniper STATES : NM TX MEXICO BLM PHYSIOGRAPHIC REGIONS : 7 Lower Basin and Range 13 Rocky Mountain Piedmont 14 Great Plains KUCHLER PLANT ASSOCIATIONS : K059 Trans-Pecos shrub savanna K086 Juniper - oak savanna K087 Mesquite - oak savanna SAF COVER TYPES : 66 Ashe juniper - redberry (Pinchot) juniper 68 Mesquite 239 Pinyon - juniper 242 Mesquite SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Mexican buckeye has not been listed as a dominant or indicator in published classification schemes.
SPECIES: Ungnadia speciosa
WOOD PRODUCTS VALUE : Wood of the Mexican buckeye is reddish-brown, soft, brittle, and close grained . Sapwood is lighter in color . Plants can be cut back regularly for firewood . IMPORTANCE TO LIVESTOCK AND WILDLIFE : Mexican buckeye is seldom browsed by domestic livestock except during periods of food scarcity [6,23]. Fruit and leaves contain the toxic alkaloid saponin which is poisonous to livestock . Mexican buckeye may be responsible for occasional losses of cattle and goats in parts of southern New Mexico . Seeds are eaten by insects and some small mammals after they fall to the ground . PALATABILITY : Mexican buckeye browse is relatively unpalatable to domestic livestock. The sweet-tasting seeds  are readily eaten by a variety of small mammals . NUTRITIONAL VALUE : Nutritional value of Mexican buckeye foliage has been documented as follows : (percentage composition - dry weight) Protein Ether Crude N-free H2O Ash Potash Lime Magnesia Phosphoric extract fiber extract acid ------------------------------------------------------------------------------ 12.03 2.20 21.94 51.19 6.62 6.02 1.39 3.17 0.54 0.36 COVER VALUE : Mexican buckeye presumably provides cover for a variety of wildlife species. Trees may also produce shade for domestic livestock. VALUE FOR REHABILITATION OF DISTURBED SITES : NO-ENTRY OTHER USES AND VALUES : Mexican buckeye can be planted as a shade tree or as an ornamental in landscaping [6,20]. It is attractive when either planted alone or intermixed with other species . Fragrant, showy flowers enhance its attractiveness during the spring [19,23]. Mexican buckeye can be trained as a hedge, planted onto berms of earth-covered homes, and used as a "display thicket shrub" . Flowers provide nectar for honey bees, and it is considered a good honey plant . Children of west Texas reportedly use the round seeds of Mexican buckeye as playing marbles . However, in view of its toxicity to rats in laboratory studies, this use should probably be discouraged. OTHER MANAGEMENT CONSIDERATIONS : Toxicity: The sweet seeds of Mexican buckeye taste like pistachio nuts and were formerly considered as a potential human food source . Stanford  and his colleagues reportedly consumed up to 20 seeds without suffering ill effects. However, results of laboratory tests with rats soon put an end to these culinary experiments. Rats which had ingested Mexican buckeye seeds soon exhibited numerous signs of both neurological and organ damage and most died within 3 weeks . Seeds can cause dizziness, nausea, and abdominal discomfort in humans [6,16]. Spider infestations: Fruit of Mexican buckeye is commonly infested with spiders . Where infestations occur, seeds may be "glued" to the capsules by web-building activities and commonly remain on the tree until the following spring. On the average, approximately 10 percent of all fruit is infested .
SPECIES: Ungnadia speciosa
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
GENERAL BOTANICAL CHARACTERISTICS : Mexican buckeye grows as an upright or spreading, multistemmed shrub or small tree [19,23]. It commonly reaches 4 to 15 feet (1.2-4.6 m) in height but on favorable sites can grow to 30 feet (9.5 m) with trunk diameters of 10 inches (25.4 cm) [6,19,23]. Bark is a mottled light gray to brown, with shallow fissures developing on old trunks [16,23]. Slender brown to orange, pubescent twigs become reddish-brown and glabrous with age . Some roots grow horizontally along the rock or soil surface while others extend deep into the vertical face of soft rock cliffs . Leaves of Mexican buckeye are deciduous, alternate, and odd-pinnately compound [17,18]. The three to seven ovate-lanceolate leaflets are leathery with crenate-serrate margins [16,23]. The upper surface is dark green and glabrous, whereas the lower surface is paler and pubescent to glandular . Small fragrant flowers are rose to purplish-pink and are borne in clusters on bare stems [16,19,23]. Fruit is a woody, reddish-brown, three-lobed pod or capsule 1 to 1.5 inches (2.5-3.8 cm) in diameter [16,19]. The shiny, dark brown to black, rounded seeds average approximately 0.4 to 0.6 inch (1-1.5 cm) in diameter . Seeds are smooth, leathery and "buckeyelike" [17,19,23]. Each capsule generally contains a single seed . RAUNKIAER LIFE FORM : Undisturbed State: Phanerophyte (nanophanerophyte) Undisturbed State: Phanerophyte (microphanerophyte) Undisturbed State: Phanerophyte (mesophanerophyte) Burned or Clipped State: Chamaephyte Burned or Clipped State: Hemicryptophyte REGENERATION PROCESSES : Mexican buckeye reproduces through seed or by vegetative means. However, seedlings are rarely observed under natural conditions . Seed: Mexican buckeye first flowers during the 3rd year when plants have reached approximately 2 to 3.5 feet (0.6-1.1 m) in height . Each plant produces an abundance of seed annually. Some seed falls from the plant when fruit first ripens in the fall. However, some fruit may persist on the tree through winter [19,22]. Seedlings grow well in full sun on warm, damp soil. Those grown in even partial shade may appear stunted and eventually die. Conditions necessary for seedling establishment, such as warm, but moist soil and full sun, may be rare in the desert Southwest. Seedling establishment generally occurs only in years with unusually abundant late summer and early fall rainfall. During the course of an 8-year study, Stanford  observed Mexican buckeye seedlings in only 1 year. Under optimum greenhouse conditions, germination rates can exceed 95 percent . Seedling emergence by planting date has been documented as follows : date collected date of color 1st yr. and planted emergence of seed development 6/14 8/2 green stunted 6/21 7/28 green stunted 6/28 7/22 green stunted 7/6 7/24 faint brn. patch stunted 7/13 7/28 dark brn. patch weak 7/20 8/3 mostly dark brn. good 7/27 8/9 fully brown good 8/3 8/18 fully brown good 8/10 8/22 fully brown good 8/17 8/30 fully brown good 8/24 9/9 fully brown good 8/31 9/18 fully brown good Vegetative regeneration: Mexican buckeye coppices readily . Plants cut to ground level at 4- or 5-year intervals retain good vigor and growth . SITE CHARACTERISTICS : Mexican buckeye grows on lower mountain slopes and foothills, in arroyos, and along streambanks in valley bottoms [6,16,23]. It commonly occurs on the exposed face or rim of chalk caprock cliffs and along fractures or depressions in igneous or limestone outcrops [5,19]. Mexican buckeye is tolerant of full sun and thrives under drought conditions . It is commonly associated with deciduous riparian woodlands, oak-juniper woodlands, and desert grassland communities [5,7]. Plant associates: Common associates include Ashe juniper (Juniperus ashei), netleaf hackberry (Celtis reticulata), live oak (Quercus fusiformis), Lacey oak (Q. glaucoides), Texas persimmon (Diospyros texana), black walnut (Juglans nigra), bumelia (Bumelia lanuginosa), and black cherry (Prunus serotina) . Soils: Mexican buckeye typically grows on well-drained calcareous soils [19,22,23]. Elevation: In Trans-Pecos Texas, Mexican buckeye grows from 1,000 to 6,500 feet (305-1,981 m) in elevation . SUCCESSIONAL STATUS : Mexican buckeye grows in a number of riparian woodland communities. These woodlands generally represent climax or "postclimax" communities . Little is known about the successional role of Mexican buckeye in oak-juniper woodlands or in desert grassland communities. SEASONAL DEVELOPMENT : Mexican buckeye flowers approximately 10 days after buds first appear . In Trans-Pecos Texas, flowering occurs from March to June . Leaves develop soon after the flowers . Fruit ripens in July  or as late as August or October . Fruit turns dark brown in the fall and unopened capsules may persist through the winter . Plants become dormant within 2 weeks of the first frost or at leaf fall .
SPECIES: Ungnadia speciosa
FIRE ECOLOGY OR ADAPTATIONS : Wright  notes that fires have historically been relatively unimportant in the Chihuahuan Desert, which is dominated by shrubs rather than grasses. Mexican buckeye often occurs in deciduous riparian woodlands, which burn infrequently. It is not known whether Mexican buckeye possesses specific adaptations to fire. However, the majority of shrubs indigenous to southwestern Texas sprout readily from the root crown after fire . Mexican buckeye coppices from the root crown after mechanical removal , and postfire sprouting is possible. Natural seedling establishment is extremely rare , but limited seedling establishment from off-site sources may occur in unusually moist years. FIRE REGIMES : Find 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". POSTFIRE REGENERATION STRATEGY : survivor species; on-site surviving root crown or caudex off-site colonizer; seed carried by animals or water; postfire yr 1&2
SPECIES: Ungnadia speciosa
IMMEDIATE FIRE EFFECT ON PLANT : The effects of fire on Mexican buckeye have not been well documented. Aboveground portions of the plant are presumably killed by fire. However, postfire survival of the root crown is possible, if not likely. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : The response of Mexican buckeye to fire is not well known. Plants coppice readily after mechanical removal , and a similar response is possible after fire. Establishment of some seed from off-site may occur in years of unusually abundant summer and fall rainfall. However, seedling establishment is extremely rare under ordinary conditions . DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Bock and Bock  report that prescribed fire is "difficult to manage and potentially very destructive" in established riparian woodlands of the Southwest. These relatively rare and fragile areas provide important food and cover for desert wildlife . Because browse and cover are often limited in these areas, burning is not generally recommended .
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