By Bill Ward
Published in The Boerne Star on November 12, 2004
The recently discovered 150 to 200 big red sages (Salvia penstemonoides) growing along Cibolo Creek in southern Kendall County are by far the largest known natural population of this rare endemic plant.
The once-large patch of big red sage on Frederick Creek near Boerne has dwindled to a few rosettes. Other natural stands of big red sage are known in only two localities, one in Bandera County and one in Real County, and neither of these sites has more than a few plants.
Big red sage is not in danger of extinction. It is easily germinated from seed and is widely grown in gardens of Texas and many other places outside Texas. Natural populations, however, are endangered. The conservation status of Salvia penstemonoides at the state, federal and global levels is ranked as “critically imperiled.” The genetic makeup of big red sage may make this plant especially susceptible to extinction in the wild. According to a study of the ribosomal DNA of Salvia penstemonoides by Schaal, Smith and Schmid (1992, Journal of the National Wildflower Center), big red sage has low genetic diversity.
These authors analyzed cellular material of plants from Frederick Creek and Big Joshua Creek in Kendall County and from Lost Maples in Bandera County. Their results indicated little or no variation exists in the DNA of Salvia penstemonoides, either within an individual plant or among the three geographic populations.
Genetic diversity is essential for long-term survival of a species when they are forced to adapt to environmental changes. The authors conclude that the low genetic diversity in big red sage, together with the few small populations, may make this Central Texas endemic “susceptible to extinction for both genetic and demographic reasons.”
Nearly all historical records show that big red sage was found growing in the calcareous soils of the Edwards Plateau, usually on the walls of limestone canyons. I am suspicious about localities in Guadalupe and Wilson Counties where Salvia penstemonoides supposedly was collected in the mid- and late-1800s, because the geology and soils of those areas are so different from most localities where big red sage was found.
Why are most of the known stands of big red sage growing on steep canyon walls in association with other uncommon plants such as mockorange (Philadel-phus ernestii and P. texensis) and sycamore-leafed snowbell (Styrax platanifolia)?
Is this because these plants have been driven to these cryptic habitats as the result of intensive browsing by goats, cattle and deer?
Do deer browse Salvia penstemonoides? Out on the low stream terrace of the Frederick Creek locality last summer, the lone big red sage bloom stalk stood immediately adjacent to heavily deer-browsed Texas ash, yet it was not nibbled. The several big red sage rosettes growing nearby were not browsed either. However, a friend of mine near Fredericksburg has many big red sage plants in the unfenced yard near his house, but when he tried to transplant some of them to his creek bottom, they were eaten by deer.
Do big red sage prefer sun or shade? The big population on Cibolo Creek grows on a northeast-facing cliff which gets afternoon shade. However, across the creek are a few big red sage which get afternoon sun.
In my own yard is a clump of Salvia penstemonoides growing in a shaded area and another clump growing in full sun. I can’t tell that there is much difference in how well these two bunches of plants grow and spread or in how well they bloom.
What are the factors controlling a viable population of big red sage in nature? To help answer this question, members of the Boerne chapter of NPSOT are planning to cooperate with the Cibolo Nature Center (CNC) and the Texas Parks & Wildlife in annual monitoring of Texas’ largest population of big red sage on Cibolo Creek.
In addition, our NPSOT chapter and CNC intend to initiate a long-term project to establish and monitor “natural” stands of big red sage in the riparian habitat of the CNC. We hope to test such factors as deer browsing, soil moisture, drainage, slope steepness and direction, exposure to sun, competition from other plants, and resistance to droughts and floods.
I’ll keep you posted on our progress.
