Hymenoxys texana
| Hymenoxys texana | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Hymenoxys |
| Species: | H. texana
|
| Binomial name | |
| Hymenoxys texana | |
| Synonyms[4] | |
| |
Hymenoxys texana is a rare species of flowering plant in the aster family known by the common names prairie dawn, Texas prairie dawn-flower, and Texas bitterweed. It is endemic to Texas, where it is found primarily in the general vicinity of Houston. It is threatened by the loss of its habitat. It is a federally listed endangered species of the United States.
Hymenoxys texana is an annual herb with delicate reddish or purplish stems growing only 10 or 15 centimeters (4-6 inches) tall. The leaves have rubbery, glandular blades which may be simple or divided into lobes, particularly at mid-stem. The inflorescence is a solitary flower head or an open cluster of several heads. Each head is under a centimeter wide and has 6 to 8 yellow ray florets each 2 or 3 millimeters long.[5] The ray florets are often tucked behind the phyllaries. The center of the head has 30–75 tiny disc florets.[6]
Hymenoxys texana grows primarily in two ecoregions: the grasslands of the Western Gulf Coastal Plain and in the South Central Plains in Texas,[7] although it has also been found in one county in the Texas Blackland Prairies.[8] It can be found on open, barren stretches of saline sandy soil at the base of Mima mounds. The soil is often coated with a slick of algae (Nostoc sp.) during the wet season.[3] The soil dries, cracks, and becomes powdery in the dry season.[6][7] Few other plants occur on this substrate, but prairie dogshade (Limnosciadium pumilum) can sometimes be associated.[3]
Hymenoxys texana is known only from six counties, all located in Texas: Harris, Fort Bend, Waller, Trinity, Gregg, and Madison Counties.[8] It was first described in 1891 from a specimen taken near Hockley.[3][9] Few specimens were noted after this and by 1979 the species was thought to be extinct. Just two years later it was relocated.[6] The primary threat to Hymenoxys texana is habitat loss. Most of the occurrences of the plant are within or near the Houston metropolitan area, which is undergoing rapid growth.[1][7] Habitat is being claimed for residential and other development.[1]
References
- ^ a b c Hymenoxys texana. Archived 2002-11-23 at the Wayback Machine The Nature Conservancy.
- ^ "Texas prairie dawn-flower (Hymenoxys texana)". Environmental Conservation Online System. U.S. Fish & Wildlife Service. Retrieved 23 December 2025.
- ^ a b c d 51 FR 8681
- ^ The Plant List, Hymenoxys texana (J.M.Coult. & Rose) Cockerell
- ^ Hymenoxys texana. Flora of North America.
- ^ a b c Hymenoxys texana. Archived 2010-12-15 at the Wayback Machine Center for Plant Conservation.
- ^ a b c Texas Prairie Dawn. Texas Parks & Wildlife.
- ^ a b Texas Prairie Dawn-Flower (Hymenoxys texana) 5-Year Review: Summary and Evaluation. Non-published. U.S. Fish and Wildlife Service, Texas Coastal Ecological Service, August 31, 2022. Accessed December 24, 2025
- ^ Coulter, John Merle & Rose, Joseph Nelson. 1891. Botanical Gazette 16(1): 27–28