Allium platycaule
Broad stemmed onion
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Family: Alliaceae · Type: Herb · Native
Allium platycaule (Broad stemmed onion) is a native California herb in the Alliaceae family, recognized by key diagnostic feature is the unique flat, winged stem.
Broad stemmed onion is a California native perennial found in northern Sierra Nevada Mountains, Modoc Plateau, and high Cascade Range on rocky or sandy slopes at elevations of 1,500 to 2,500 meters. Flowering from May to June, this plant produces bright pink to rose flowers in dense clusters with 30 to 90 individual blossoms. Growing with stout stems 7 to 25 centimeters tall that are distinctively flat and winged, it emerges from a small ovoid bulb. Its two leaves are sickle-shaped, nearly twice the length of the stem and flat in profile. The flowers feature lance-linear perianth parts with long-pointed tips that spread while in bloom and become erect when setting fruit.
Identification and appearance
Key characters: 24 sympatric species; key diagnostic feature is the unique flat, winged stem
Habitat and range
Habitat: Common. Rocky or sandy slopes
Elevation: 1500-2500 m
California counties: Modoc, Lassen, Nevada, Plumas, Placer, Butte, Mono, Tehama, Sierra, El Dorado, Shasta, San Luis Obispo, San Francisco
Outside California: southern Oregon, western Nevada
Bloom period
Allium platycaule blooms May-Jun.
How to tell it apart
vs Triteleia: Allium smells like onion when crushed; triplet lily has no smell.; vs Agapanthus: Allium smells like onion; lily-of-the-Nile has no smell and much larger flowers.; vs Dipterostemon: Allium smells like onion when crushed; ookow has no onion smell.; vs Nothoscordum: Allium smells like onion when crushed; false garlic has no smell.; vs Tulbaghia: Allium has flowers in tight umbels; society garlic has flowers in loose open clusters.
Frequently asked questions
Is Allium platycaule native to California?
Yes. Allium platycaule is native to California (recorded as native).
When does Allium platycaule bloom?
Allium platycaule blooms May-Jun.
Where in California does Allium platycaule grow?
Allium platycaule occurs in Modoc, Lassen, Nevada, Plumas, Placer, Butte, Mono, Tehama and other counties, at elevations of 1500-2500 m.
What plant family does Allium platycaule belong to?
Allium platycaule is in the Alliaceae family, genus Allium.
What habitat does Allium platycaule grow in?
Allium platycaule grows in Common. Rocky or sandy slopes.
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.