BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Ungnadia speciosa | Mexican Buckeye 



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 [23].  Some roots grow horizontally along the rock or
soil surface while others extend deep into the vertical face of soft
rock cliffs [19].

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 [23].

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 [16].  Seeds are
smooth, leathery and "buckeyelike" [17,19,23].  Each capsule generally
contains a single seed [23].


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 [19].

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 [19].
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
[19] observed Mexican buckeye seedlings in only 1 year.  Under optimum
greenhouse conditions, germination rates can exceed 95 percent [19].
Seedling emergence by planting date has been documented as follows [19]:

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 [19].  Plants
cut to ground level at 4- or 5-year intervals retain good vigor and
growth [19].


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 [19].  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) [1].

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 [16].


SUCCESSIONAL STATUS : 
Mexican buckeye grows in a number of riparian woodland communities.
These woodlands generally represent climax or "postclimax" communities
[4].  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
[19].  In Trans-Pecos Texas, flowering occurs from March to June [16].
Leaves develop soon after the flowers [19].  Fruit ripens in July [19]
or as late as August or October [23]. Fruit turns dark brown in the fall
and unopened capsules may persist through the winter [19].  Plants
become dormant within 2 weeks of the first frost or at leaf fall [19].

Related categories for Species: Ungnadia speciosa | Mexican Buckeye