By Bill Ward
Published in The Boerne Star on August 13, 2002
Lady Bird Johnson reportedly said that the movement to use native plants in landscaping and gardening was not meant to exclude all other plants from consideration. Indeed, most of us who take pride in cultivating native plants also enjoy growing exotic plants.
There are many plants from other lands that go well with our natives. After all, there are many exotic plants that have the same characteristics we admire in the natives. That is, they do well in the Texas Hill Country without needing extra water, special soils, or frequent doses of fertilizer and pesticide.
Those characteristics sometimes are a problem instead of a blessing.
Some imported plants do so well that they are able to move out of the yard and into the countryside and become a threat to native species. Nowadays I think twice before planting any exotic where its seeds might fall into a drainage and be transported away from my yard during a hard rain. Wind-transported seeds are almost impossible to control.
Until recently, I thought the lilac chaste-tree or vitex (Viteх agnus-castus) to be among native-compatible exotic trees that we could safely use in landscaping. But this summer I found vitex growing along Bear Creek in Bandera County, and Susan Sander says she has seen it at several spots along the Guadalupe River in Kerr County.
Another exotic tree that more recently has become popular in Hill Country landscapes is the Chinese pistachio or Chinese mastic (Pistacia chinensis), which can vie with the bigtooth maple for providing spectacular fall color.
For many years this tree was thought to be a “safe” import. Apparently, it took a long time to acclimate, but now the Chinese pistachio is becoming an invasive exotic in southeastern Texas. Whether it can become invasive in the colder, drier Hill Country may be yet unknown.
Early warning: a Chinese pistachio seedling has come up in our yard forty feet from the big one that was planted 19 years ago.
Many of my colleagues in the Native Plant Society will roll their eyes at this one, but I like crape myrtle (Lagerstroemia indica), an early import from China.
The worst thing that can be said about crape myrtle is that it is a cliché in Hill Country landscaping.
On the positive side, it is highly drought-resistant and blooms in the heat of summer. The attractive smooth trunks with peeling bark might be compared to trunks of Texas persimmon and Texas madrone.
To me, crape myrtle doesn’t seem out of place planted with many of our native shrubs and flowers. More importantly, there apparently are no reports of this old standby escaping into the wild to compete with the Hill Country natives.
The multi-flowered and everblooming Abelia is another long-used non-native shrub that grows well and looks good among natives in Hill Country gardens. Bees and butterflies like it, too. I hope there are no reports that abelia has invaded the natural landscape in this part of Texas.
Several native-compatible exotic plants have been introduced from the Southwest US and Mexico, such as a number of sages (Salvia spp.), Copper Canyon daisy (Tagetes lemmonii), and arroyo sweetwood (Myrospermum sousanum), among many others. Deer-resistant Mexican oregano (Poliomintha longiflora) comes from northeastern Mexico.
The Mediterranean gives us one of our most useful native-compatible evergreen shrubs, rosemary (Rosmarinus spp). Russian sage (Perovskia atriplicifolia), which can be a drought-tolerant garden companion for our native blue salvias, comes from central Asia.
There are many introduced foreign plants that can be used to complement the natives we cultivate. Let’s be careful that none of them become “naturalized” in the wild and begin to compete with the Hill Country natives. The native plants might not win the battle.
