Amsonia tomentosa
Gray amsonia
(c) Melanie J. Davis, some rights reserved (CC BY) · licence
Family: Apocynaceae · Type: Herb · Native
Amsonia tomentosa (Gray amsonia) is a native California herb in the Apocynaceae family, recognized by Range edge species - this is the westernmost extension of a genus primarily distributed in the southeastern United States.
Gray amsonia is a California native perennial found in the northern slopes of the San Bernardno Mountains and desert regions at elevations of 300 to 1,800 meters in desert plains and canyons. Flowering from March to May, this plant produces white to blue flowers with a corolla tube about 15 millimeters long, slightly inflated above the middle. Growing with several to many stems emerging from a woody crown, the plant reaches 16 to 36 centimeters tall with few to many branches. Its leaves are 2 to 4 centimeters long, ovate-lanceolate in shape, and acute at both ends, with a short or absent petiole. The fruit develops 3 to 8 centimeters long and is often constricted between seeds, potentially breaking into individual seed segments.
Identification and appearance
Key characters: Range edge species - this is the westernmost extension of a genus primarily distributed in the southeastern United States
Habitat and range
Habitat: Desert plains, canyons
Elevation: 300-1800 m
California counties: Riverside, San Bernardino, Inyo, Los Angeles
Outside California: to Utah
Bloom period
Amsonia tomentosa blooms Mar-May.
How to tell it apart
vs Oxypetalum: Amsonia has narrow alternate leaves spiraling up stem; Oxypetalum has broader opposite leaves and distinctive inflated milkweed-type flowers.; vs Vinca: Amsonia grows strictly upright with alternating leaves; Vinca trails along ground with opposite leaves.; vs Cycladenia: Amsonia has thin leaves in alternate arrangement; Cycladenia has thick waxy opposite leaves.; vs Apocynum: Amsonia has leaves alternating up the stem; Apocynum has leaves in opposite pairs.; vs Nerium: Amsonia is a soft-stemmed herb with alternate leaves; Nerium is a woody shrub with whorled leathery leaves.
Frequently asked questions
Is Amsonia tomentosa native to California?
Yes. Amsonia tomentosa is native to California (recorded as native).
When does Amsonia tomentosa bloom?
Amsonia tomentosa blooms Mar-May.
Where in California does Amsonia tomentosa grow?
Amsonia tomentosa occurs in Riverside, San Bernardino, Inyo, Los Angeles, at elevations of 300-1800 m.
What plant family does Amsonia tomentosa belong to?
Amsonia tomentosa is in the Apocynaceae family, genus Amsonia.
What habitat does Amsonia tomentosa grow in?
Amsonia tomentosa grows in Desert plains, canyons.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.