Thymophylla tephroleuca | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Genus: | Thymophylla |
Species: | T. tephroleuca |
Binomial name | |
Thymophylla tephroleuca (S.F.Blake) Strother | |
Synonyms | |
Dyssodia tephroleuca |
Thymophylla tephroleuca (formerly Dyssodia tephroleuca) is a rare species of flowering plant known by the common names ashy pricklyleaf [2] and ashy dogweed. It is endemic to Texas in the United States, where it occurs in two counties near the Mexican border. It became rare due to the destruction and degradation of its habitat. [1] [3] It is a federally listed endangered species of the United States.
This plant, a shrub or subshrub, produces a clump of stems up to 30 centimeters tall. The herbage is ashy gray-green, gray, or whitish due to a layer of white woolly hairs. The leaves are linear to threadlike and are arranged alternately along the stems. They measure 1 to 1.5 centimeters long. The inflorescence is a flower head with a bell-shaped involucre of woolly-haired phyllaries. There are 12 or 13 yellow ray florets and about 30 disc florets at the center. The fruit is an achene with a pappus of scales. [4] Blooming occurs mostly in March through May but it may bloom at other times depending on rainfall. [1]
Thymophylla tephroleuca prefers fine sand or sandy-loam soils. [5] Its current habitat is predominately shrub-invaded grasslands. [5]
This plant is likely a relict, a rare species remaining in a grassland habitat type that was once more common. [6] Most of the local territory has converted to brushland dominated by cenizo (Leucophyllum frutescens) blackbrush (Coleogyne ramosissima), and creosote bush (Larrea tridentata). Other dominant plant species include mesquite (Prosopis glandulosa), goatbush (Castela texana), anacahuita (Cordia boissieri), and javelina brush (Microrhamnus ericoides). The introduced buffelgrass (Cenchrus ciliaris) is common. [7]
By 1979 this plant was known from a 1-acre (0.0040 km2) in Zapata County, Texas. By the time the plant was placed on the Endangered Species List in 1984, there was a single population containing about 1300 plants bisected by a highway. [6] [7] More populations have been found in the years since, and currently there are six in Zapata and Webb Counties. [3]
Highway maintenance is an ongoing threat to the species, as the plant grows directly next to a highway. Dying plants have been observed at the highway's edge, a possible sign of herbicide application. The installation of a gas pipeline likely destroyed some plants and its maintenance is a threat to others in the area. Grazing is not a direct threat because cattle do not eat the foul-smelling plant, but their trampling may compact the soil. The introduction of buffelgrass for better grazing has led to drastic changes in the plant community, because it spreads and competes easily with other species. [7]
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Packera layneae, known by the common name Layne's ragwort and Layne's butterweed, is a rare species of flowering plant in the aster family.
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 and the Mexican states of Tamaulipas and Coahuila. It occurs in coastal prairie, grassland, and mesquite shrubland habitat. It has declined because its native habitat has been cleared for development, with remaining open savanna invaded by non-native grasses such as buffelgrass. 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. It is not certain that the plant still exists in Mexico. This is a federally listed endangered species of the United States.
Aristida portoricensis is a rare species of grass known by the common name pelos del diablo. It is endemic to Puerto Rico, where it is known from two locations, one in a residential area of Mayagüez and one in the Sierra Bermeja. Two other known sites have been extirpated by development of the habitat. It is a federally listed endangered species of the United States.
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Deinandra conjugens is a rare species of flowering plant in the family Asteraceae known by the common names Otay tarplant and Otay tarweed. It is native to a small section of far northern Baja California in Mexico, its range extending north into San Diego County, California, in the United States. One isolated population has been reported from the hills east of Cayucos in San Luis Obispo County.
Echinocactus horizonthalonius is a species of cactus known by several common names, including devilshead, turk's head cactus, blue barrel cactus, eagle's claw, horse maimer, horse crippler, and visnaga meloncillo. It is native to the southwestern United States and northern Mexico, where it occurs in Chihuahuan Desert and Sonoran Desert habitats, particularly on limestone substrates. One of its varieties is a federally listed endangered species of the United States.
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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 known only from 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.
Mirabilis macfarlanei is a rare species of flowering plant in the four o'clock family known by the common name MacFarlane's four o'clock. It is native to Idaho and Oregon in the United States, where it is only known from three river canyons. It faces a number of threats and is federally listed as a threatened species of the United States.
Spiranthes delitescens is a rare species of orchid known by the common names reclusive lady's tresses, Canelo Hills lady's tresses, and Madrean lady's tresses. It is native to Arizona in the United States, where there are only four occurrences. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species of the United States.
Tetramolopium arenarium is a rare species of flowering plant in the family Asteraceae known by the common name Maui tetramolopium. It is endemic to Hawaii, where it is known only from the island of Hawaii. It is extirpated from Maui. It is threatened by the degradation of its habitat. It is a federally listed endangered species of the United States.
Townsendia aprica is a rare species of flowering plant in the family Asteraceae known by the common name Last Chance Townsend daisy. It is endemic to Utah in the United States, where it is known from three counties. It faces a number of threats and it is a federally listed threatened species of the United States.
Artemisia rigida is a species of flowering plant in the aster family known by the common names scabland sagebrush and stiff sagebrush. It is native to the northwestern United States, in Washington, Idaho, and Oregon. It has been recorded in western Montana but these sightings may have been misidentifications.
Eriogonum visheri is a species of wild buckwheat known by the common names Dakota wild buckwheat and Visher's buckwheat. It is native to the Great Plains in the United States, where it is known from North Dakota, South Dakota, and Montana.
Xanthisma coloradoense is a species of flowering plant in the family Asteraceae known by the common name Colorado tansyaster. It is native to Colorado and Wyoming in the United States.
Physaria thamnophila is a rare species of flowering plant in the mustard family known by the common name Zapata bladderpod. It is native to Texas in the United States, where it is known from Zapata and Starr Counties. The plant is threatened by the loss and degradation of its habitat. It is federally listed as an endangered species.