Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

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

Cirsium ochrocentrum, Yellowspine Thistle

Amsonia tomentosa, Woolly Bluestar

Woolly Bluestar has white flowers with blue or green tints. The flowers are in a terminal cyme and each has 5 petals and 5 sepals. The flower lobes are erect and linear as shown in the photo. Amsonia tomentosa Woolly Bluestar has green leaves, some hairless and some with gray hairs as shown in the photo. The leaves alternate along the stem and are pointed on both sides. Amsonia tomentosa Woolly Bluestar is a short plant with several woody branches. Flowers are terminal on the tips of these stems and may be in small clusters as shown here. Amsonia tomentosa Woolly Bluestar prefers elevations from 100 to 5,000 feet (300 - 1800 m) and blooms from March through May. Habitat preferences include sandy deserts, desert plains and canyons. Amsonia tomentosa

Scientific Name: Amsonia tomentosa
Common Name: Woolly Bluestar

Also Called: Gray Amsonia

Family: Apocynaceae, Dogbane Family

Synonyms: (Amsonia brevifolia, Amsonia tomentosa var. tomentosa)

Status: Native

Duration: Perennial

Size: 8 to 24 inches (2 - 6 dm) tall

Growth Form: Forb/herb; plants short, glabrous to woolly or gray-tomentose; stems several to many from a woody crown, branches few to many.

Leaves: Green, alternate, leaf petiole short, hairy (tomentose) or hairless (glabrous) lanceolate to rhombic-ovate; leaves acute and both ends.

Flower Color: White with some green or blue tinting, flowers in terminal, compound cyme; 5 sepals and the lobes are erect, linear, 5 petals, corolla tube present, broadest at the apex; fruit pod-like follicles, distinctly constricted between seeds, seeds elliptic.

Flowering Season: March to May

Elevation: 100 to 5,000 feet (300 - 1800 m)

Habitat Preferences: Sandy deserts, desert plains and canyons.

Recorded Range: Woolly Bluestar is found in the southwestern United States in AZ, CA, NM, NV, TX, UT and northern Mexico (Chihuahua).

North America & US County Distribution Map for Amsonia tomentosa.

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

Genus Information: In North America there are 16 species and 16 accepted taxa overall for Amsonia. Worldwide, The Plant List includes 19 accepted species names and a further 17 scientific names of infraspecific rank for the genus. The genus Amsonia was published in 1788 by Thomas Walter.

In the Southwestern United States: Arizona has 7 species of genus Amsonia, California and Nevada each have 1 species, New Mexico has 6 species, Texas has 8 species and Utah has 2 species. All data approximate and subject to revision.

There are 2 varieties in Amsonia tomentosa;
Amsonia tomentosa var. stenophylla, Woolly Bluestar, (AZ, NM, TX, UT);
Amsonia tomentosa var. tomentosa, Woolly Bluestar, (AZ, CA, NM, NV, UT)

Comments: Woolly Bluestar is known for two distinct forms. One is green and smooth (glabrous) and the one pictured above, a gray woolly form. Flowers are white with bluish or greenish tint.

Importance to Wildlife, Birds and Livestock
No data available

Special Value to Native Bees, Butterflies and Insects
No data available

The genus Amsonia is a name in honor of Dr. John Amson, an 18th century Virginia physician. The genus Amsonia was published in 1788 by Thomas Walter.
The species epithet "tomentosa" means densely covered with matted wool or short hair, a reference to its wolley or "tomentose" hairs.

No data available

Date Profile Completed: 01/12/2020
Kearney, Thomas H., Peebles, Robert H., 1960, Arizona Flora, University of California Press, Berkley and Los Angeles, California.
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database and USGS ITIS search - (accessed 01/12/2020)
The Plant List (2013). Version 1.1. Published on the Internet; (accessed 01/12/2020). s
McLaughlin, Steven, P. 1994. Vascular Plants of Arizona: Apocynaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 164-168.
Thomas J. Rosatti & Lauramay T. Dempster 2012, Amsonia tomentosa, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on January 12, 2020.
'Amsonia tomentosa', Wikipedia, The Free Encyclopedia, 4 January 2020, 02:38 UTC, [accessed 12 January 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 //2020)