Oreocarya crassipes, a heterostylous species in the plant family Boraginaceae, is endangered. The species restricted to the Fizzle Flat Lentil in Brewster County, Texas in the are just north of Big Bend National Park. The plant grows in harsh conditions. Indeed, the landscape is referred to as moonscape given the barren environment with a limited number of plants growing in the area. O. crassipes is one of the more dominant species in the region, especially in particular areas where the species can be locally abundant.
Other species of Oreocarya grow in the area as well, but O. crassipes can be identified by:
- a perennial habitat, including a usually well-developed basal rosette,
- a salverform, white corolla with a yellow center that surpasses the calyx
- heterostylous flowers, and
- rugose nutlets.
The leaves also are usually covered by a dense indument, and older leaves are frequently gray-green, although newer leaves tend to be green in color. While others species of Oreocarya are present in West Texas, the restricted habitat of O. crassipes can also be used to help distinguish this species from others in the genus.
Oreocarya crassipes is known from a small number of populations. In a 1994 report on the species, Poole identified 10 populations that included a total of 4554 individuals. However, a more recent study by Warnock and Williams found that that the number of plants was at least twice this as large, and their study included a smaller number of populations. While this is hopeful data for the longevity of the species, it is important to remember that all of populations are on private land and that endangered plants do not have the same type of protective status as endangered animals. Consequently, the species still remains vulnerable to development and recreational activities (e.g., off-road vehicles, mountain bikes, motorcycles, etc.) in the area as well as catastrophic events. Indeed, during a recent trip to the area, I observed that many plants in some populations appeared to be infected by a fungus which was having detrimental impacts on the plants. Researchers, such as Warnock and Williams and those at the Desert Botanical Garden, have attempted to grow the plants ex situ, but success has been limited. The plants tend to grow best in their native habitat, although perhaps as more attempts are made to grow the plants in other areas, there will be greater success.
Along with general information on the geographic distribution of the species, the general ecology and edaphic specialization of O. crassipes has been studied, and while the plant can grow in a variety of soil conditions ex situ, the plants appear to be obligate gypsophile in its native habitat. According to Warnock and Williams, the gypsum soils have a higher moisture content than other types of soils in the area; therefore, this could provide another reason for O. crassipes to grow in the seemingly harsh conditions. The plants also produce pyrrolizidine alkaloids, which can help prevent the plant from herbivory, another reason that the plants can survive on the moonscape.
While ecological aspects of O. crassipes have been studied, the population genetics of the species remains unknown. Despite the small both geographic area the plant inhabits and the number of populations, patterns of demography, migration, and genetic structure have been investigated in detail. Currently, Cohen and his students are conducting this type of study, on four populations of O. crassipes, to better understand the variation within the species at morphological and genetic levels. These studies are ongoing, and results will be posted to the site as they are known.