Jeff Davis county is primarily an upland county, with the Davis Mountains and surrounding plateau making up the bulk of the county. In the extreme western part of the county, lies the only other mountain range in Jeff Davis county, the Sierra Viejas. Jeff Davis county is made up predominately of Tertiary volcanic rocks and gravels eroded from these formations. Jeff Davis county encompasses 2,259 square miles.

Jeff Davis county receive an average of about 18.5" of rain per year, with the mountainous areas receiving slightly more, and the grassland areas somewhat less. Pinyon-juniper-oak habitats dominate the mountainous areas, with a scattering of Ponderosa pine at the higher, wetter elevations. Jeff Davis county is much grassier than most counties where alterna are found, with extensive grasslands dominating much of the western portion of the county, and grasses are also common in the Pinyon-juniper-oak habitats of the uplands.

POPULAR L. alterna LOCALITIES

Specimens

Limpia Canyon, TX 17
Between Ft. Davis and Wildrose Pass, Tx Hwy 17 follows the canyon of Limpia Creek, and several good stretches of L. alterna habitat exist here. Traffic pressure can be high, and there are numerous blind curves which can be fairly dangerous, so proceed with caution when collecting here.

Tx 118 - between Ft Davis and McDonald Observatory

Specimens

McDonald Observatory, Tx 118
In the vicinity of McDonald Observatory, NW of Ft. Davis there is one tremendous road cut which has produced a small number of alterna. However, this area is very high elevation, mostly over 6000 feet, and therefore cools rather rapidly at night.

Specimens

Musquiz Canyon, TX 118
To the SW of Ft. Davis, TX 118 passes through Musquiz Canyon, a fairly impressive stretch of alterna habitat, where strangely few alterna have been collected. Traffic can be high here, as the road connects Ft. Davis and Alpine, two of the largest towns in the Trans-Pecos.