Scientific: Ungnadia speciosa
Common: Mexican buckeye, Texas buckeye
Family: Sapindaceae
Origin: Range extends from the Edwards Plateau of south-central Texas west to Trans-Pecos Texas, and into southern New Mexico and northeastern
Mexico.

Pronounciation: Ung-NAD-ee-a spee-see-O-sa

Hardiness zones
Sunset
7-9, 12-13
USDA 7-11

Landscape Use: For oasis and xeric landscape gardens as a background, screen, informal hedge, single or group of multiple trunk small trees. Useful in higher elevation landscapes of Arizona such as in Prescott, Payson and Flagstaff.

Form & Character: Rounded and spreading large shrub to small tree, appears mesic.

Growth Habit: Moderate growth rate into an upright or spreading, multi-stemmed shrub or small tree, commonly reaching 4 to 30 feet in height with a greater spread.

Foliage/texture: Deciduous foliage, alternate, and odd-pinnately compound, 3 to 7 ovate-lanceolate leaflets per leaf, leathery with crenate-serrate margins.  The adaxial (upper) leaf surface is dark green and glabrous, whereas the abaxial (lower) surface is paler and pubescent to glandular. The bark on the trunk is a mottled light gray to brown, with shallow fissures developing on older trunks; medium coarse texture.

Flowers & fruits: Small fragrant flowers are rose to purplish-pink and are borne in clusters on bare stems.  Fruits are a woody, reddish-brown,
three-lobed pod or capsule 1 to 1.5 inches in diameter
. The shiny, dark brown to black, rounded seeds average approximately 0.5 inch in diameter. Seeds are smooth, leathery and 'buckeye like'. Each capsule generally contains a single seed. Seed pods are persistent during winter months.

Seasonal color: Pink flowers in early spring and yellow fall color in cooler climates (no fall color in Phoenix).

Temperature: Heat loving, cold tolerant to 0oF.

Light: Full sun

Soil: Well drained soils are best.

Watering: Little additional water from irrigation after establishment. Requires no water during the winter months and only every one to two weeks during summer. More frequent irrigations can dramatically increase the growth rate.

Pruning: Very little needed except to develop good structure when young and to maintain shape when mature.

Propagation: Fresh seed propagation under greenhouse conditions can result in up to 90% germination rates.

Disease and pests: None

Additional comments: The fruit and leaves of Mexican buckeye contain the toxic alkaloid saponin which is poisonous to livestock. Children in west Texas reportedly use the round seeds of Mexican buckeye as playing marbles. People eating the seeds have experienced dizziness, nausea, and abdominal discomfort. Wood useful as firewood.