Astragalus tricarinatus
Triple-ribbed milkvetch
(c) Melanie J. Davis, some rights reserved (CC BY) · licence
Family: Fabaceae · Type: Subshrub · Native
Conservation status: CNPS 1B.2 · Endangered
Astragalus tricarinatus (Triple-ribbed milkvetch) is a native California subshrub in the Fabaceae family, recognized by distinctive 3-sided fruit morphology.
Triple-ribbed milkvetch is a rare (CNPS 1B.2) California native perennial found in eastern San Bernardino Mountains near Whitewater and Morongo Valley in exposed rocky desert slopes and canyon walls at elevations of 450 to 1,250 meters. Flowering from February to May, this plant produces cream-colored flowers with a distinctive banner petal that curves back nearly 45 degrees, arranged in loose clusters of 5 to 15 blooms. Growing with stiff, erect stems 5 to 25 centimeters tall, it forms a loose tufted habit with fine silvery hairs covering its structure. Its compound leaves extend 7 to 20 centimeters long and feature 17 to 27 narrow, silvery-green leaflets each 3 to 12 millimeters long, densely covered in strigose hairs. The fruit is a distinctive three-sided linear pod 24 to 42 millimeters long, ascending from a short stout stalk and containing 20 to 24 seeds.
Identification and appearance
Key characters: 17 sympatric species; distinctive 3-sided fruit morphology is diagnostic
Habitat and range
Habitat: Exposed rocky slopes, canyon walls along desert washes
Elevation: 450-1250 m
California counties: San Bernardino, Riverside, Mono
Bloom period
Astragalus tricarinatus blooms Feb-May.
Conservation status
CNPS 1B.2 · Endangered
How to tell it apart
vs Vicia: Astragalus has racemes of flowers; vetches (Vicia) have tendrils at leaf tips and climbing or sprawling habit.; vs Oxytropis: Astragalus keel tip is rounded to slightly pointed; Oxytropis keel has a pronounced pointed beak.; vs Cleomella: Astragalus has pea-shaped flowers; Cleomella has 4-petaled cruciform flowers with long stamens.; vs Lupinus: Astragalus has pinnate compound leaves; lupines have palmate leaves (leaflets radiating from one point).; vs Dalea: Astragalus has typical pea flowers; Dalea has tiny flowers with petals attached to the stamen tube.
Frequently asked questions
Is Astragalus tricarinatus native to California?
Yes. Astragalus tricarinatus is native to California (recorded as native).
When does Astragalus tricarinatus bloom?
Astragalus tricarinatus blooms Feb-May.
Where in California does Astragalus tricarinatus grow?
Astragalus tricarinatus occurs in San Bernardino, Riverside, Mono, at elevations of 450-1250 m.
What plant family does Astragalus tricarinatus belong to?
Astragalus tricarinatus is in the Fabaceae family, genus Astragalus.
Is Astragalus tricarinatus rare or endangered?
Astragalus tricarinatus carries California Rare Plant Rank 1B.2, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
- Astragalus trichopodus — Santa barbara milkvetch
- Astragalus trichopodus var. antisellii — Antisell milkvetch
- Astragalus trichopodus var. lonchus — Santa barbara milkvetch
- Astragalus trichopodus var. trichopodus — Santa barbara milkvetch
- Astragalus umbraticus — Bald mountain milkvetch
- Astragalus webberi — Webber's milkvetch
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
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.