That Grape Kool Aid Plant

Every spring there is a buzz about a purple-flowering plant in landscapes where we live,

“What is that plant with the clusters of dangling purple flowers that smell like grape flavored Kool Aid”

The Texas mountain laurel (Dermatophyllum secundiflorum, formally known as Sophora secundiflora) is a large shrub or small tree normally with glossy, evergreen leaves. The flowers are reminiscent of wisteria flowers, with a very powerful scent that is likened to grape flavored Kool Aid or grape soda.

A member of the bean family (Fabaceae), the flowers are followed by pods that contain orange to red (sometimes white) glossy seeds. The seeds are poisonous, though even if swallowed, the seed coat is so thick, actual poisonings are rare, with the exception of people who have made jewelry (beads) out of the seeds and wearing the necklaces, sucked on the seeds. Even this has only produced nausea rather than a serious poisoning.

These plants can grow up to 15 feet or more high and wide, and naturally are shrubby. With some pruning they can be made into small patio trees (best to let the plant grow as a shrub for a long time, then prune it up). Texas mountain laurel is evergreen and looks great most of the year. Young plants get a little caterpillar in the warm months, mostly on the new growth. It is the larval stage of the genista broom moth (Uresiphita reversalis) and causes no lasting damage. Plants regrow new leaves readily, and the unsightliness usually only lasts a month or so. Bees especially love the flowers of this species, with their rich nectaries.

The larvae of genista broom moth feeding on Texas mountain laurel

The adult form of genista broom moth

This species is native to the southwestern United States (Texas, New Mexico) and Mexico (Chihuahua and Coahuila south to Hidalgo, Puebla and Querétaro).

‘Silver Sierra”, a silvery selection of Texas Mountain Laurel

There is a silver selection, sometimes called “Silver Sierra” which has all the same traits as the green species, but with very silvery leaves. This selection is slightly less prone to the moth larvae.

The Arizona species, Dermatophyllum arizonicum

Another species that is rare in the trade, though we are working on making it more common, is the native Arizona necklace pod (Dermatophyllum arizonicum, formally known as Calia arizonica). Please recall what we said about using seeds as necklace beads (this species is also probably somewhat poisonous).

The foliage of the Arizona species

It reaches about 20’ high and wide and has more sage-green leaves, and lavender or light purple flowers. If you see this plant for sale, grab it, because it is very rare, and a very cool plant.

Both species are hardy to about 10°F, take full to partial sun, and moderate to low water with good drainage. Though plants are reputed for being somewhat slow-growing, they can be pushed to grow faster if planted in full sun, and watered regularly in the warm season. Some organic material in the surrounding soil will assist plants in growing faster. Birds love to nest in the full-grown plants because of their evergreen foliage and bushy, protective, dense canopies.