| 词条 | Ambrosia cheiranthifolia |
| 释义 |
|status = G2 |status_system = TNC |genus = Ambrosia |species = cheiranthifolia |authority = A.Gray }} 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.[2] 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).[3] 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.[4] It is not certain that the plant still exists in Mexico.[5] This is a federally listed endangered species of the United States. 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.[6]This plant sometimes occurs alongside slender rush-pea (Hoffmannseggia tenella), another endangered species.[5] References1. ^Biota of North America Program 2014 county distribution map 2. ^[https://www.biodiversitylibrary.org/item/91651#page/87/mode/1up 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] 3. ^USFWS. Determination of Endangered Status for the Plants Ayenia limitaris (Texas Ayenia) and Ambrosia cheiranthifolia (South Texas Ambrosia). Federal Register August 24, 1994. 4. ^The Nature Conservancy 5. ^1 Texas Parks and Wildlife 6. ^1 2 Flora of North America External links{{Taxonbar|from=Q4741887}} 8 : Ambrosia (plant)|Flora of Coahuila|Flora of Tamaulipas|Flora of Texas|Flora of the U.S. Rio Grande Valleys|Plants described in 1859|Taxa named by Asa Gray|Endangered flora of the United States |
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