Ambrosia cheiranthifolia is a rare species of flowering plant known by the common names South Texas ambrosia and Rio Grande ragweed. It is native to the coast of South Texas[1] and the Mexican states of Tamaulipas[2] and Coahuila.[3] It occurs in coastal prairie, grassland, and mesquite shrubland habitat.[2] It has declined because its native habitat has been cleared for development, with remaining open savanna invaded by non-native grasses such as buffelgrass (Cenchrus ciliaris).[4] Today there are perhaps 20 populations remaining, but some of these may have very few genetic individuals because the species is clonal, with many cloned plants attached by one rhizome.[5] It is not certain that the plant still exists in Mexico.[6] This is a federally listed endangered species of the United States.
| Ambrosia cheiranthifolia | |
|---|---|
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Ambrosia |
| Species: | A. cheiranthifolia
|
| Binomial name | |
| Ambrosia cheiranthifolia | |
Ambrosia cheiranthifolia is a rhizomatous perennial herb growing erect to a maximum height around 40 centimeters. Several clones usually grow in a dense patch. The stems and herbage are silvery green with a coating of rough gray hairs. The oblong leaves are 3 to 7 centimeters long and oppositely arranged on the lower plant but alternate on the upper stems. The inflorescence contains staminate flower heads in clusters with a few pistillate heads in leaf axils below the clusters.[2]
This plant sometimes occurs alongside slender rush-pea (Hoffmannseggia tenella), another endangered species.[6]
References
edit- ^ Biota of North America Program 2014 county distribution map
- ^ a b c Flora of North America
- ^ Gray, Asa in Emory, William Hemsley 1859. Report on the United States and Mexican boundary survey :made under the direction of the secretary of the Interior . Botany 2(1): 87
- ^ USFWS. Determination of Endangered Status for the Plants Ayenia limitaris (Texas Ayenia) and Ambrosia cheiranthifolia (South Texas Ambrosia). Federal Register August 24, 1994.
- ^ The Nature Conservancy
- ^ a b Texas Parks and Wildlife
