Astragalus pycnostachyus
Loco weed
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Family: Fabaceae · Type: Herb · Native
Astragalus pycnostachyus (Loco weed) is a native California herb in the Fabaceae family.
Loco weed is a California native perennial herb found in coastal areas of California, often growing in open grasslands and coastal scrub environments. Flowering from March to August, this plant produces green-white or cream-colored flowers in dense, overlapping clusters with petals 7 to 10 millimeters long. Growing with stout, somewhat erect stems 40 to 90 centimeters tall that are reddish and hollow, it forms clumped, leafy clusters with a white-woolly appearance. Its compound leaves are 3 to 15 centimeters long, featuring 23 to 41 narrow leaflets densely packed along the stem. The distinctive fruit is reflexed, ovate, and slightly inflated, with a 5 to 8 millimeter stiff, hooked beak that adds to the plant's unique architectural structure.
Identification and appearance
Key characters: Geographically isolated, no sympatric species
Habitat and range
California counties: Marin, San Mateo
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 pycnostachyus native to California?
Yes. Astragalus pycnostachyus is native to California (recorded as native).
Where in California does Astragalus pycnostachyus grow?
Astragalus pycnostachyus occurs in Marin, San Mateo.
What plant family does Astragalus pycnostachyus belong to?
Astragalus pycnostachyus is in the Fabaceae family, genus Astragalus.
Related species
Other California species in the same genus, family, or bioregion.
- Astragalus pycnostachyus var. lanosissimus — Ventura marsh milkvetch
- Astragalus pycnostachyus var. pycnostachyus — Coastal marsh milkvetch
- Astragalus rattanii — Rattan's milkvetch
- Astragalus rattanii var. jepsonianus — Jepson's milkvetch
- Astragalus rattanii var. rattanii — Rattan's milkvetch
- Astragalus ravenii — Raven's milkvetch
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.