Cryptantha crassipes is a rare species of flowering plant in the borage family

Boraginaceae

Boraginaceae, the Borage or Forget-me-not family, include a variety of shrubs, trees, and herbs, totaling about 2,000 species in 146 genera found worldwide.A number of familiar plants belong to this family....

 known by the common name Terlingua Creek cat's-eye. It is endemic to Brewster County, Texas

Brewster County, Texas

Brewster County is a county located in western part of the US state of Texas, along the border with Mexico. It is one of the nine counties that comprise the Trans-Pecos region of West Texas. As of the 2000 census, the population is 8,866. In 2009, the population was estimated to be 9,481. Its...

, where it is known from only ten populations totaling about 5000 plants. All of the occurrences are within a ten-kilometer radius. This is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

.

This is a perennial herb producing several erect stems reaching a maximum height around 25 centimeters. There is a clump of basal leaves around the stem bases. The herbage is covered in silvery soft and bristly hairs. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is a head of yellow-throated white flowers. The plants are often coated in a soot

Soot

Soot is a general term that refers to impure carbon particles resulting from the incomplete combustion of a hydrocarbon. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolyzed fuel particles such as cenospheres,...

y black fungus

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

.

This plant grows only on the Fizzle Flat lentil, a small geologic formation in the Terlingua Creek

Terlingua Creek

Terlingua Creek is a stream in the U.S. state of Texas. It is a tributary of the Rio Grande....

 watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 just north of Big Bend National Park

Big Bend National Park

Big Bend National Park is a national park located in the U.S. state of Texas. Big Bend has national significance as the largest protected area of Chihuahuan Desert topography and ecology in the United States, which includes more than 1,200 species of plants, more than 450 species of birds, 56...

. This lentil is a unique expanse of limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 rock which is rich in gypsum

Gypsum

Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...

 and bound with clay

Clay

Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

. The formation is pale yellow in color because of its mineral makeup. The chalk

Chalk

Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....

y rock breaks into plates and contains many fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s. The area is very dry and it receives full, hot sunlight. The formation is about 50 feet thick. Locals call the formation a "moonscape". The lentil is almost totally devoid of plant life; this species and other hardy plants, such as Castilleja elongata and Lycium berberioides, occur around the edge of the lentil.

The rare plant is limited to a specific substrate. The area is affected by human activity in several ways. The land is all privately owned and unprotected. Off-road vehicle

Off-road vehicle

An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks...

s drive on the badlands. They are used for grazing

Grazing

Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...

 of livestock

Livestock

Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...

 and bentonite

Bentonite

Bentonite is an absorbent aluminium phyllosilicate, essentially impure clay consisting mostly of montmorillonite. There are different types of bentonite, each named after the respective dominant element, such as potassium , sodium , calcium , and aluminum . Experts debate a number of nomenclatorial...

 is mined

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

in the area.

Further reading

• Moon, C. G. (1953). Geology of Agua Fria Quadrangle, Brewster County, Texas. Geological Bulletin 64:2 151.