Astragalus oocarpus
San diego milkvetch, San Diego Milkvetch
(c) Madeleine Claire, some rights reserved (CC BY) · licence
Family: Fabaceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Astragalus oocarpus (San diego milkvetch) is a native California herb in the Fabaceae family, recognized by large size, hollow stems, and inflated fruits.
San diego milkvetch is a rare (CNPS 1B.2) California native perennial found in central San Diego County in chaparral and oak woodland openings at elevations of 400 to 1,700 meters. Flowering from May to August, this plant produces cream-colored flowers in clusters with 20 to 75 widely ascending blossoms, featuring a banner petal that recurves 70 to 90 degrees. Growing with stout, hollow stems 6 to 13 decimeters tall that are widely ascending to erect, it develops a robust leafy structure. Its compound leaves contain 17 to 35 widely lanceolate leaflets, each 6 to 33 millimeters long, with prominently raised midveins and glabrous surfaces except for sparsely strigose margins. The fruit is distinctive, forming an erect, greatly inflated pod 15 to 25 millimeters long with a stiff-papery texture.
Identification and appearance
Key characters: 21 sympatric species; key features are large size, hollow stems, and inflated fruits
Habitat and range
Habitat: Openings in chaparral, oak woodland
Elevation: 400-1700 m
California counties: San Diego, San Luis Obispo, San Benito, Riverside, Inyo
Bloom period
Astragalus oocarpus blooms May-Aug.
Conservation status
CNPS 1B.2
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 oocarpus native to California?
Yes. Astragalus oocarpus is native to California (recorded as native).
When does Astragalus oocarpus bloom?
Astragalus oocarpus blooms May-Aug.
Where in California does Astragalus oocarpus grow?
Astragalus oocarpus occurs in San Diego, San Luis Obispo, San Benito, Riverside, Inyo, at elevations of 400-1700 m.
What plant family does Astragalus oocarpus belong to?
Astragalus oocarpus is in the Fabaceae family, genus Astragalus.
Is Astragalus oocarpus rare or endangered?
Astragalus oocarpus carries California Rare Plant Rank 1B.2, state rank S2?.
Related species
Other California species in the same genus, family, or bioregion.
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.