Texas: Diverse AND Unique
An endemic species is an organism that only occurs in a specific geographic area. It can be endemic to a political area, such as a country or state, or to a large climate region like the Southeast US. Endemic species may also be restricted to certain ecosystems: a basin or watershed, or maybe even a two-mile stretch of river. If populations of species become isolated by environmental barriers, they can evolve into separate and unique species from their cousins in other disjunct populations.
Texas is a truly diverse state, especially when you consider our ecosystems. From the mountains and deserts of West Texas to the gulf coastal prairies, and the Pineywood forests of East Texas, each region has a unique ecosystem. If we look at EPA Level III ecoregion maps of the Lower 48, Texas has 12 distinct ecoregions which is only second to California’s 13 and tied with Oklahoma!
Level III Ecoregions of North America from the EPA
So, Texas has a beautiful diversity that we know and love, but how unique are these ecosystems? Only four ecoregions in the Lower 48 states are fully contained within a single state, and Texas has two of them: the Edwards Plateau and the Texas Blackland Prairie. These ecoregions unique to Texas contribute to the abundance of species found nowhere else in the world.
Unique Level III Ecoregions of lower 48 by Stephen Ramirez
Alright, Texas is exceptionally diverse AND unique, but why does it matter? Biodiversity is vital for healthy ecosystems and human needs. Conserving our diverse endemic species is critical because they tend to face greater threats of extinction or decline due to their limited habitats. The presence of Texas endemic species is one of the factors we consider when we evaluate our conservation projects.
Our biodiversity is also something we should take immense pride in. As Texans, we are the sole stewards of these unique species, and thus their fates are in our hands. Once they’re gone, they’re gone. It is about rooting for the home team. Allow me to share my favorite plants from team “Only in Texas”. My draft picks, if you will.
Texas Barberry (Mahonia swaseyi)
Range: Edwards Plateau - Balcones Canyonlands
Global Conservation Status: G3 Vulnerable - At moderate risk of extinction or collapse due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.
Habitat: Limestone ridges and canyons; 150-600 m altitude.
Notes: Texas Barberry is a cousin of the widespread Agarita shrub. Whereas Agarita has three leaflets, Texas Barberry leaves typically have 5,7, or 9 leaflets. In my experience, Wimberley is the epicenter of the Texas Barberry population. Usually found on the edge of an oak motte alongside its Agarita cousin. Additional Info.
Photos by Stephen Ramirez, map of verified observations from iNaturalist
Wand Butterfly Bush (Buddleja racemosa)
Range: Edwards Plateau – Balcones Canyonlands
Global Conservation Status: G4 Apparently Secure – At fairly low risk of extinction or collapse due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors.
Habitat: Streams, creeks and springs at elevations of 250 – 750 m.
Notes: This plant is often found growing out of barren limestone, either by preference or necessity, either of which is remarkably impressive.
Photos by Stephen Ramirez, map of verified observations from iNaturalist
Heller’s Beardtongue (Penstemon triflorus)
Range: Edwards Plateau – Balcones Canyonlands
Global Conservation Status: G3 Vulnerable - At moderate risk of extinction or collapse due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.
Habitat: Generally, throughout the oak-juniper woodlands.
Other Names: Heller’s Penstemon, Hill Country Penstemon
Notes: Heller’s Beardtongue is a striking species to find due to its exquisite and showy flowers in a habitat that otherwise prevents significant mass of showy forbs due to limited light availability. Interestingly, specimens were collected in Mexico in the 20th century but none since 1991.
Photos by Stephen Ramirez, map of verified observations from iNaturalist
Texas Wild Rice (Zizania texana)
Range: Upper 2 miles of the San Marcos River
Global Conservation Status: G1 Critically Imperiled - Federally Endangered, at very high risk of extinction or collapse due to very restricted range, very few populations or occurrences, very steep declines, very severe threats, or other factors.
Habitat: Found throughout riffles and pools of the upper San Marcos River, within a narrow range of water conditions.
Notes: Texas Wild Rice, once restricted to a precarious population covering about 240 square meters, has grown substantially following restoration, plantings, and management of water discharge. Its range has increased to over 10,000 square meters. Maintaining these gains into the future will require active management and the continuation of broad partnerships. Additional Info.
Photos by Stephen Ramirez, map of verified observations from iNaturalist
“Only in Texas” summer campaign!
For the month of July, when you donate $100+, you’ll receive an exclusive “Only in Texas” t-shirt, featuring five plants found only in Texas. This shirt is more than just a piece of clothing—it’s a symbol of your commitment to protecting the natural heritage of our state. Every dollar you donate helps conserve the habitats and water sources that the “Only in Texas” plants rely on.
