Ungnadia

( ung - NAW - dee - uh )

At-A-Glance Information

Commonly called Mexican Buckeye, this genus of deciduous trees and large shrubs is native to northeastern Mexico, southern New Mexico and western Texas. They reach 15-20 feet tall and just as wide, with dark green foliage. Flowers are showy and rose-pink, blooming in springtime before leafout. The blooms attract butterflies and other pollinators. These plants are naturally multi-trunked but can be trained to have a singular trunk. Mexican Buckeye needs full sun to light shade and little water. Take care when planting these shrubs and trees in your garden, as seeds are poisonous. There is only one species, Ungnadia speciosa, in the genus, which is a member of the plant family Sapindaceae. Mexican Buckeye grows best in zones 10-13.

Caring for and pruning ungnadia Trees

Plant Mexican Buckeye in a place in the landscape that receives full sun exposure. These trees need between 6 and 8 hours of direct sun each day to flower well. These trees will need a sheltered place in most landscapes, especially if temperatures are cool. In too cold temperatures, these trees will not flower. Mexican Buckeye prefers to grow in well-draining, dry soil that has a pH of between 6.1 and 8.5. It can tolerate poor soils, but performs best in moderately nutrient-rich substrate. If local soils are clay, heavy, or nutrient-poor, amend the planting site with plenty of organic material and/or sand before installing. Apply a thick layer of mulch around the base of trees to suppress weed growth, increase soil moisture retention, and help to regulate soil temperatures. Water newly planted trees regularly, helping them to build a strong root system. At maturity, these trees are quite drought-tolerant, and can get by on rainwater alone for most of the year. During extended dry periods, deep water trees. Avoid over-watering, especially over the winter months when the tree is dormant.

Prune in late winter or early springtime, removing dead, damaged, diseased, or crossing branches and opening up the canopy. Pruning young trees to establish a central leader is suggested, though these trees are also often seen as multi-trunked specimens. Apply a feeding with a dressing of organic compost around the base of trees in early springtime. This should be sufficient to support the growth and flowering for the year. If trees seem to be struggling, they may benefit from an additional feeding with a balanced, slow-release fertilizer. Take care to not over-fertilize or use fertilizers that are too high in nitrogen, as this will lead to a flush of new foliage growth at the expense of flowering.

Propagation

Ungnadia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Ungnadia tree, follow the instructions below:

Propagating Ungnadia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 4-6 inch softwood portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Ungnadia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds in late summer or early fall when the seed capsules turn reddish-brown and begin to split open. Seeds should be shiny, black and hard.
  3. Mexican Buckeye seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics. The more seeds you plant, the more chances you will have to get the resulting tree you want. Place your seeds in lukewarm water for 24-48 hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float.
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 14-21 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Ungnadia seed pods.
Ungnadia seeds.

Problems and Pests

Mexican Buckeye trees are not typically affected by many pests or diseases, but they can be susceptible to the following in certain cases:
  • Powdery Mildew
  • Verticillium Wilt
  • Anthracnose
  • Rose Gray Mold
  • Chili Thrips
For more information on these pests and diseases, consult the following pages:
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Gallery

Mexican Buckeye trees produce pink flowers with protruding stamens in springtime.
Flowers bloom on these trees before leafout.
Ungnadia trees are commonly used in front yards, where they can be admired.
New foliage typically is flushed with reddish tones.
Fall color of Ungnadia trees is yellow to orange-red.
Ungnadia trees have a very handsome natural shape, and do well in smaller gardens.

Videos

These trees need some protection in cooler climates.
Lean all about Mexican Buckeye.

Resources

Ungnadia speciosa
Ungnadia speciosa (Mexican Buckeye)
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 643, Ungnadia speciosa
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