COMMON NAMES: TEXAS BUCKEYE, MONILLA
BOTANICAL NAME: Ungnaidia speciosa (oong-NAD-ee-ah spee-see-OH-sa)
FAMILY: Sapindaceae (Soapberry Family)
TYPE: Deciduous small tree
HEIGHT: 20 feet
SPREAD: 20 feet
FINAL SPACING: 10 to 20 feet
NATURAL HABITAT AND PREFERRED SITE: Grows wild on mountain slopes and in canyons across the Trans Pecos and also in central Texas including as far north as Harris, Tarrant and Dallas Counties. Mexican buckeye grows well in limestone outcroppings but will adapt to normal garden soil in sun or shade. It primarily should be used as an understory tree. I have found it growing out of cracks in the solid granite at Enchanted Rock in San Antonio. It seems to grow the best west of the Brazos River. It actually prefers alkaline soils.
IDENTIFICATION INFORMATION: Mexican buckeye is a shrub or small tree that grows multi trunked or single stemmed. It normally has an irregular overall shape. It has purple flowers in the spring that bloom just after the bloom of the redbuds. Flowers come out just before the foliage or as the immature foliage starts to emerge. Brilliant yellow fall color and decorative 3 compartment seed pods on bare branches in the winter.
FLOWERS AND FRUIT: The flowers appear in the spring as the leaves emerge or just before. Fragrant purple flowers often mistaken for the redbud which blooms earlier in the spring. The flowers are small, fragrant, and pink to purple, appearing in closely attached clusters. The seed are round, shiny, black and hard. The plant usually flowers in its third season.
BARK: Very thin and light gray, can be easily damaged by maintenance equipment. With age it becomes mottled gray to brown and develops shallow fissures.
FOLIAGE: Looks a little bit like pecan having compound leaves 5 to 12 inches long with 5 to 7 leaflets. Mexican buckeye has one of the most brilliant yellow fall color displays of all trees that will grow in Texas.
CULTURE: Mexican buckeye is very easy to grow in sun or shade in any well drained soil. Slow to moderate growth and needs very little water and fertilizer. Although drought tolerant it can also stand moist soils.
PROBLEMS: Very few problems if any at all. An ornamental tree that should be used much more. I guess the fact that the seed are reported to be poisonous is a possible problem. The leaves and fruit have been reported to cause mild poison to livestock but are seldom browsed unless the only foliage around.
PROPAGATION: The shiny black seed can be harvested beginning in late summer through October when the capsules turn a dark reddish brown and crack open. After a short drying period the seed can be planted into moist soil and will germinate within 3 weeks without any seed treatment. Seed will germinate best in warm soil. I have not had much luck at this point growing Mexican buckeye from cuttings.
INSIGHT: Mexican buckeye is not a member of the true buckeye family. Bees make an excellent honey from the flowers.