Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Hymenothrix wislizeni, Trans-Pecos Thimblehead

Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora    Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora    Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora    Hymenothrix wislizeni, Trans-Pecos Thimblehead, Southwest Desert Flora

Scientific Name: Hymenothrix wislizeni
Common Name: Trans-Pecos Thimblehead
Also Called: TransPecos Thimblehead
Family: Asteraceae, Sunflower Family
Synonyms: ( )
Status: Native
Duration: Annual or biennial.
Size: Up to 3 feet.
Growth Form: Forb/herb, subshrub; multiple upright slender green stems, branching near the top.
Leaves: Green, alternate, leaves more dense near the bottom of stems; simple pinnately divided into 3 narrow linear lobes (middle-left photo); leaf margins slightly turned in or revolute.
Flower Color: Yellow; ray flowers, disk flowers and anthers yellow; ray flowers with 3 to 8 florets; disk flowers with 15 to 30 florets; flower heads numerous in terminal clusters; fruit is an achene.
Flowering Season: June to December.
Elevation: 2,500 to 5,500 feet.
Habitat Preferences: Sunny open areas, plains, mesas, washes, sandy and gravelly soils.
Recorded Range: Relatively rare in the United States Trans-Pecos Thimblehead is found only in AZ, NM and TX. It is also found in Baja California and northern Mexico. In Arizona; Yavapai County and the southern half of Arizona excluding the southwest corner. New Mexico it is found in the southwest corner and two isolated populations. Texas is poorly represented with only a few specimens recorded.

U.S. Weed Information: No data available.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: No data available.
Threatened/Endangered Information: No data available.

Genus Information: 3 species in Hymenothrix, all in southwestern United States. All 3 species native to Arizona.

Comments: Trans-Pecos Thimblehead is similar in appearance to both Wright’s Thimblehead, Hymenothrix wrightii and Loomis' Thimblehead, Hymenothrix loomisii. The most obvious differences are in the flowers both Wright’s and Loomis’ Thimblehead flowers are discoid only without the ray flowers found on Trans-Pecos Thimblehead.

Other differences are in the flower colors, Wright’s Thimblehead flowers have white or pinkish corollas and pinkish anthers and Loomis' Thimblehead has cream or yellow flowers but again, they lack the ray flowers found only on Trans-Pecos Thimblehead. Middle-right small photo above shows cypsela seed and pappi.

Date Profile Completed: 8/26/2012, updated: 06/30/2015; Updated, 07/25/2015
References:
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database
Arizona Flora, Kearney, Thomas H., Peebles, Robert H., 1960, University of California Press, Berkley and Los Angeles
John L. Strother, FNA | Family List | FNA Vol. 21 | Asteraceae | Hymenothrix, Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford. (accessed 08/26/2012)
SEINet for synonyms, scientific names and recorded geographic locations, http://swbiodiversity.org/seinet/