San Antonio Express-News Saturday, December 23, 2000 Calvin R. Finch, Ph.D., Director of Conservation, SAWS, and Horticulturist

TEXAS MOUNTAIN LAUREL

Texas mountain laurel, Sophora secundiflora, is one of the native plants that was accepted by the nursery industry as it exists in the wild, and it has become a star performer of the landscaping industry in Texas.

Texas mountain laurel is evergreen with shiny green foliage. It grows naturally as a shrub to about 15 feet, but can be trained to a small tree by cutting out all but one stem at ground level. It looks especially nice as a specimen plant with three to five stems.

The light purple blooms in early spring (usually early March) are spectacular. They have a powerful fragrance that reminds me of the grape bubble gum that I paid a penny for as a kid. Other "smell experts" have described the fragrance as that of grape Kool-Aid.

Plant Texas mountain laurel in full sun. It does best in well-drained soils but tolerates most clays. Do not put it in soggy, low situations. Texas mountain laurel does not grow fast in the best conditions, but you can increase the growth rate to about two feet per year if it is growing in good soil and it is fertilized twice per year. Fast-growing Texas mountain laurels, however, are slow to begin blooming. A Texas mountain laurel growing at a moderate rate may bloom when it reaches four to five feet, but a heavily fertilized plant may have to be seven or eight feet tall.

Texas mountain laurel is a tough plant. It is a premiere xeriscape plant. Excessive moisture in poorly drained soil can kill them but drought usually cannot. Borers may occasionally attack mountain laurel. If the holes are noticed in time, a borer spray applied in April and August may help. The most common complaint is the Uresiphita reversalis caterpillars. The larvae themselves are hard to find but the damage can be quite noticeable; one day the shrub is fully leafed and the next day there will be bare stalks. The caterpillars are no threat to healthy, established Texas mountain laurel. They may slow the growth of young plants. Control the Uresiphita caterpillar with Bt products such as Dipel, Thuricide, or Bio-Worm Killer.

· Texas mountain laurel is a disciplined, compact grower. Pruning is rarely necessary or advisable. The flower stalks form on silvery, flexible stems that I call "snakes." Unfortunately, the "snakes" are not appreciated by some gardeners and are occasionally pruned off, eliminating the year's bloom. In addition to inappropriate pruning and heavy fertilization, too much shade is a main reason for limiting the bloom. Full sun is essential for good bloom, even though the foliage can remain attractive for years after they get overgrown by oaks and other shade trees.

· The Texas mountain laurel is called mescal bean by some gardeners. It forms a seedpod that contains red, round beans by late summer. The beans cause hallucinations at low levels. The beans are also very poisonous if the alkaloids within are released. The same seed coating that protect the seed from drought, however, will allow it to be swallowed and pass through our bodies without harm, in most cases.

· Texas mountain laurel is an expensive nursery plant because it is a relatively slow grower and does not transplant easily. Do not waste your time trying to transplant specimens more than about 2.5 feet from the wild; the survival rate is low. If you are careful with container-grown plants, the survival rate is high.

The normal way to start new plants is with seed. If you want a Texas mountain laurel in a specific spot, obtain and plant about five seeds at the location about one inch deep. One or two will probably germinate within a year.

Increase the germination rate by nicking the seed coat with a nail file and then soak the seed in water for a day. An even better way to use the seed is to harvest and plant it before the seed coat hardens. When the pods are full-size with marble-sized seeds clearly defined within the pod, collect the seed when the pod turns from green to crème-brown. The seed coat has not completed the hardening of its drought-resisting coat and germination rates are higher.

Texas mountain laurel is an outstanding plant for a low water use landscape in South Texas. Even the most discriminating gardener will appreciate its landscape value.