Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

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

Cirsium ochrocentrum, Yellowspine Thistle

Hymenothrix loomisii, Loomis' Thimblehead

Loomis' Thimblehead flowers may be white as shown in the photo, cream, yellow or even bright yellow. Note that the flowers are disk flowers only, no ray flowers. Hymenothrix loomisii Loomis' Thimblehead flowers shown here in cream to yellow. Note the brownish yellow anthers arising from the middle of the floret. The fruits are called a cypsela. Hymenothrix loomisii Loomis' Thimblehead flowers attract many insects including native bees as shown in the photo and also butterflies as soon the photo below. With their brightly colored flowers plants may be visited by butterflies, moths and other insects in search of food. Hymenothrix loomisii Loomis' Thimblehead flowers are a magnet for insects. Plants bloom from June or July to October. Hymenothrix loomisii Loomis' Thimblehead leaves are green and divided into narrow linear lobes. The leaves are smooth or they may have short soft hairs. Hymenothrix loomisii Loomis' Thimblehead in found at elevations from 3,500 to 7,000 feet (1,067-2,134 m). Plant habitat preferences include mesas, plains, and disturbed sites especially along roadsides. Hymenothrix loomisii

Scientific Name: Hymenothrix loomisii
Common Name: Loomis' Thimblehead

Also Called:

Family: Asteraceae, Sunflower Family

Synonyms: ()

Status: Native

Duration: Annual, biennial, some are short-lived perennial.

Size: 1 to 3 feet (30-91 cm) tall or more.

Growth Form: Forb/herb; stems generally green, upright, slender branching on upper stems; stems may be smooth or with small hairs.

Leaves: Green; leaves are divided into narrow or linear lobes; leaves smooth or having short soft hairs.

Flower Color: Cream to white, yellow or bright yellow; flower heads small; disk florets only, no ray florets; bracts surrounding flower heads are generally linear; the anthers arising from the middle of the floret are brown or yellow; the fruit is a cypsela.

Flowering Season: June or July to October, summer and fall after monsoon rainfall.

Elevation: 3,500 to 7,000 feet (1,067-2,134 m); below 1,000 feet (305 m) in California

Habitat Preferences: Mesas, plains and disturbed sites especially along roadsides.

Recorded Range: Rare in the United States found only in AZ, CA and NV. Also native to northern Mexico. In the southwest it is found primarily in Arizona with small populations in southeast Nevada and southern California. In Arizona it occurs in the central (Maricopa, Co.) and northwestern parts of the state. Loomis' Thimblehead is also native to central Mexico in the Sierra Madre Occidental in western Chihuahua.

North America & US County Distribution Map for Hymenothrix loomisii.

North America species range map for Thimblehead, Hymenothrix loomisii:
North American range map courtesy of Virginia Tech, Dept. of Forest Resources & Environmental Conservation

North America species range map for Thinblehead, Hymenothrix loomisii: Click image for full size map.
Click image for full size map

U.S. Weed Information: Unknown
Invasive/Noxious Weed Information: Unknown
Wetland Indicator: Unknown
Threatened/Endangered Information: Unknown

Genus Information: In North America there are 3 species and 3 accepted taxa overall for Hymenothrix. Worldwide, The Plant List includes 6 accepted species names and a further 10 scientific names of infraspecific rank for the genus.

The genus Hymenothrix was published by Asa Gray, (1810-1888), in 1849.

In the Southwestern United States: Arizona has 3 species of Hymenothrix, California, New Mexico and Texas each have 2 species, Nevada has 1 species and Utah has 0 species. Data approximate and subject to revision.

Comments: Loomis’ Thimblehead is similar in appearance to Trans-Pecos Thimblehead, Hymenothrix wislizeni, and Wright's Thimblehead, Hymenothrix wrightii. However, there are clear visible differences between all three in the flowers; Trans-Pecos Thimblehead is the only species with ray florets while Loomis' and Wright's Thimblehead only have disk florets and Loomis' flowers are cream, whitish or yellow while Wright's flowers are white or pinkish.

In Southwest Desert Flora also see: Trans-Pecos Thimblehead, Hymenothrix wislizeni and Wright's Thimblehead, Hymenothrix wrightii.

Importance to Wildlife, Birds and Livestock
Loomis' Thimblehead, Hymenothrix loomisii flowers, seeds and plants may be visited, eaten and used by hummingbirds and/or small mammals including rodents in search of food, nectar, shelter and protection through cover.

Beneficial Value to Butterflies, Bees and Insects
Loomis' Thimblehead, Hymenothrix loomisii, with their brightly colored flowers, may be visited by butterflies, moths and other insects in search of food.

The genus “Hymenothrix” (Hymeno'thrix:) from the Greek hymen, “membrane,” and thrix, “bristle,” referring to the pappus.

The genus Hymenothrix was published by Asa Gray, (1810-1888), in 1849.

The species epithet loomisii (loom'isii:) is in honor of Harold Frederick Loomis, (1896-1976).


Date Profile Completed: 8/14/2012; updated 08/14/2020
Arizona Flora, Kearney, Thomas H., Peebles, Robert H., 1960, University of California Press, Berkley and Los Angeles
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database and USGS ITIS search - (accessed 08/14/2020)
The Plant List (2013). Version 1.1. Published on the Internet; (accessed 08/14/2020).
FNA 2006, Kearney and Peebles 1969, McDougall 1973; Editor: L.Crumbacher 2011, from SEINet Field Guide, on-line; (accessed 08/14/2020).
John L. Strother, FNA | Family List | FNA Vol. 21 | Asteraceae; Hymenothrix, 2. Hymenothrix loomisii S. F. Blake, Proc. Biol. Soc. Wash. 40: 49. 1927.Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
Bruce G. Baldwin & David J. Keil 2016, Hymenothrix loomisii, in Jepson Flora Project (eds.) Jepson eFlora, Revision 4, /eflora/eflora_display.php?tid=3602, accessed on August 14, 2020.
Michael J. Plagens, Sonoran Desert Naturalist, Sonoran Desert Field Guide, Sonoran Desert Flora; on-line, accessed on August 14, 2020.
Wikipedia contributors, 'Hymenothrix loomisii', Wikipedia, The Free Encyclopedia, 21 March 2018, 14:24 UTC, [accessed 14 August 2020]
SEINet synonyms, scientific names, geographic locations, general information.
Etymology: Michael L. Charters California Plant Names: Latin and Greek Meanings and Derivations; A Dictionary of Botanical and Biographical Etymology - (accessed 08/14/2020)