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
· 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
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.