Texas mountain laurel is a unique evergreen tree with wisteria-like flowers that smell like grape soda. Here’s how to plant and care for this Chihuahuan Desert native.
Texas mountain laurel (Dermatophyllum secundiflorum) is a small evergreen tree that truly is “one of a kind” — there is no other plant like it in the desert landscape.
It has glossy dark green leaves, showy wisteria-like clusters of flowers, and fuzzy seed pods that look like large peanuts.
But its most distinctive feature is its aroma. When it blooms in the early spring, it emits a sweet scent reminiscent of grape soda. Flowers will be abuzz with hummingbirds, butterflies, bees, and other nectar-seeking insects.
Why I Like This Plant
- Glossy evergreen leaves
- Showy clusters of fragrant purple flowers
- Unusual peanut-like seed pods
- No thorns or stickers
- Low maintenance desert native
- Flowers attract butterflies, hummingbirds, bees
Things to Watch Out For
Even though Texas mountain laurel is almost always grown as a tree, it naturally grows as a large shrub. So be prepared to train it if you want yours to look like a tree.
Texas mountain laurel is very susceptible to caterpillar damage (which we’ll discuss below). If you can’t stand the thought of living with insect damage, this tree is not for you! Or consider a silver-leaved cultivar that is less susceptible to damage.
If you’re growing a Texas mountain laurel for its flowers and fragrance, be forewarned that these trees have a very short bloom period. They peak after a week or two, then the flowers quickly fade to light purple or white.
Flowers are followed by seed pods which contain bright red seeds. All parts of the plant are toxic, but especially the seeds which contain the poisonous alkaloid cytosine.
When on the tree, the pods are very hard so it’s not easy to get to the seed. However, after the seed pods fall to the ground, they degrade and the seeds become accessible. Since they are shiny scarlet red, they’re attractive to children. They are rock hard, too hard to chew, but kids could swallow them.
Optimal Growing Conditions
If you’re thinking of adding a Texas mountain laurel to your garden, you need to find a suitable place that will keep your plant healthy and looking good… while minimizing maintenance for you.
Here are the key factors to keep in mind.
Temperature
Texas mountain laurel should be grown in USDA Hardiness Zones 9 – 11. It is cold-hardy down to 10℉.
As a desert native, it can generally take extreme heat. However, it can struggle in places where summer temperatures exceed 115℉.
Sun Exposure
Texas mountain laurel needs full sun, at least 6 hours per day, to perform its best. It should not be planted in partial shade, nor should it be planted where it gets the reflected sun off an east-facing wall.
Size and Growth Rate
Texas mountain laurel is a slow grower that stays small and ultimately can reach a size of 15’ tall by 10’ wide. (By slow, I mean 3 to 6″ of growth per year.)
For this reason, it’s often recommended that you start with a decent size specimen (15 gallon) so you can enjoy it right away.
Soil
Texas mountain laurel grows in almost any well-drained soil — sandy, loamy, rocky, and limestone. It prefers the alkaline soil of its native habitat.
Other Location Considerations
Since Texas mountain laurel stays a manageable size, it’s an ideal plant for patios, courtyards, and other small spaces. You may want to plant it where its flowers and fragrance can be appreciated close up.
If you prune it like a shrub rather than a tree, its dense foliage makes a good informal hedge or background screen.
Do not plant this where kids or pets could get at the toxic pods or seeds.
Texas Mountain Laurel:
The Essentials
| Common Name | Texas mountain laurel |
| Scientific Name | Dermatophyllum secundiflorum |
| Origin | Chihuahuan Desert |
| Plant Type | Evergreen tree/shrub |
| USDA Zones | Zones 9 – 11 |
| Cold Hardiness | To 10℉ |
| Flower Color | Purple |
| Flower Season | Early spring |
| Mature Size | 15’ high x 10’ wide |
| Growth Rate | Very slow |
| Sun Tolerance | Full sun |
| Water Needs | Low |
| Pests & Diseases | Genista caterpillar |
| Cautions | All parts toxic |
| Wildlife | Attracts bees, butterflies, moths, hummingbirds Deer, rabbit resistant |
How to Plant
The rule of thumb when planting any tree in the desert is to dig a hole three times as wide as the root ball but no deeper.
Amending the soil is not recommended. Counterintuitively, backfilling with the same native soil you just dug up helps your plant develop a stronger root system.
When to Plant
The best time to plant Texas mountain laurel is in the fall. This gives it three seasons to grow roots and get established before the following summer.
The second best time is in spring, the earlier the better. This still gives your plant time to get established before the intense heat of June arrives.
How to Care for Texas Mountain Laurel
Whether you’ve recently planted a new Texas mountain laurel or have an existing one in your yard, here’s how to take care of it to keep it healthy and looking its best.
How to Water New Plants
Once you’ve got your Texas mountain laurel in the ground, watering is your most immediate concern.
Here is the recommended watering schedule for new trees planted in the spring or fall.
| Weeks 1 & 2 | Every 3 – 4 days |
| Weeks 3 & 4 | Every 6 – 7 days |
| Weeks 5 & 6 | Every 7 – 10 days |
| Weeks 7 & 8 | Every 10 – 14 days |
After week 8, gradually extend the time between waterings.
How to Water Established Plants
As your tree becomes established, there are two watering factors to consider.
- First is how often to water. This will vary with the seasons.
- Second is how much water to give your tree with each watering. This depends on the current size of your plant.
To determine the ideal watering schedule for any desert tree, you’ll find everything you need to know, including easy-to-use charts, at How to Water Desert Trees: How Often? How Much?
While established Texas mountain laurels can live without supplemental water (and do in their native habitat), they won’t look their best.
Should You Fertilize?
Texas mountain laurel gets all the nutrients it needs from native soil. And since it’s a member of the legume family (Fabaceae), it fixes nitrogen which naturally improves its surrounding soil.
How to Prune
Texas mountain laurel grows slowly and has a pleasing natural shape, so it needs very little pruning, especially if you plan to let it grow as a shrub. Lightly and selectively remove stems and branches in the spring.
Flower buds start forming in late summer. If you cut these off, you won’t have any flowers the following spring.
So do any pruning in the spring after plants have bloomed.
If you want to grow it as a multi-trunk tree, you can gradually remove lower branches to raise the crown. I suggest that you have an arborist do the first few prunings to get it off to the right start.
Safety Tip!
Keep children and pets safe.
Clip off the seed pods before they mature.
Pests
Texas mountain laurel is a favorite of the genista caterpillar or sephora worm, the larval stage of the genista broom moth (Uresiphita reversalis). These caterpillars like to dine on new leaves and young seed pods.
This can be a concern when you have a young tree, so monitor it closely. If you see caterpillars on your tree, you have several options:
- remove them by hand
- spray them off with a hose
- spray with Bt (Baccillus thuringiensis)
- spray with Captain Jack’s Deadbug
- do nothing
Doing nothing is a viable option. According to the native plant specialists at Spadefoot Nursery,
Don’t freak out when the genista broom moth makes the plant look ugly for a minute — the foliage will grow back and look better than before. As the tree gets older this damage is less extensive or noticeable.
I completely understand the urge to get caterpillars off your young plant — you want to give it the best possible chance to flourish. But leaving them alone makes a lot of sense as your tree grows larger, and handpicking and spraying become unrealistic measures.
Texas Mountain Laurel Cultivar Benefits
‘Silver Peso’ and ‘Silver Sierra’ are two cultivars that look nearly identical to the parent plant — except they have silver-gray leaves. These plants have some major benefits over the straight species:
- They are more heat tolerant
- They are less prone to caterpillar damage
- The silver leaves are quite beautiful
Plant Lover Facts
Texas mountain laurel goes by a few other common names including mescal bean, mountain laurel, and frijolillo.
It has undergone many scientific names changes over the years. The correct name is now Dermatophyllum secundiflorum, but the former name Sophora secundiflora is still commonly used.
Texas mountain laurel is native to southern Texas, New Mexico, and Mexico. It has naturalized in India, Pakistan, and Kenya.
Native Americans have been using this plant for thousands of years. Seeds that were strung to create jewelry have been found in archeological sites dating back 6,500 years. Seeds were also used as a hallucinogen and to treat earaches.
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for over 15 years.
Photo Credits
The University of Arizona Campus Arboretum
VPaleontologist, CC BY-SA 4.0, Wikimedia Commons
VPaleontologist, CC BY-SA 4.0, Wikimedia Commons