Asclepias solanoana
Serpentine milkweed, serpentine milkweed, serpentine milkweed
(c) Don Loarie, some rights reserved (CC BY) · licence
Family: Apocynaceae · Type: Herb · Native
Conservation status: CNPS 4.2
Asclepias solanoana (Serpentine milkweed) is a native California herb in the Apocynaceae family, recognized by distinctive prostrate habit on serpentine with reniform/cordate leaves.
Serpentine milkweed is a rare (CNPS 4.2) California native perennial found in the Klamath Ranges and northern Coast Ranges on serpentine outcrops at elevations of 700 to 1,600 meters. Flowering in June, this plant produces distinctive purple flowers in a well-defined spherical cluster with white-tinged hoods. Growing with prostrate stems that are slightly hairy, it spreads close to the ground with a low-growing habit. Its opposite leaves are uniquely shaped, ranging from kidney-like (reniform) to heart-shaped (cordate) or egg-shaped (ovate), with some leaves clasping the stem. The plant bears erect fruits on slightly reflexed pedicels, with seeds measuring 5.5 to 8 millimeters long.
Identification and appearance
Key characters: 5 sympatric species; distinctive prostrate habit on serpentine with reniform/cordate leaves
Habitat and range
Habitat: Serpentine outcrops
Elevation: 700-1600 m
California counties: Lake, Trinity, Colusa, Mendocino, Sonoma, Glenn, Shasta, Tehama, Napa
Bloom period
Asclepias solanoana blooms Jun.
Conservation status
CNPS 4.2
How to tell it apart
vs Gomphocarpus: Asclepias has hoods that touch or nearly touch at their edges; Gomphocarpus has gaps between hood edges.; vs Erigeron: Asclepias has rounded umbel clusters with large individual flowers; Erigeron has daisy-like flowers with many thin ray petals.; vs Lantana: Asclepias has reflexed petals with a raised hood crown; Lantana has flat-faced tubular flowers in dense rounded heads.; vs Apocynum: Asclepias has large showy flowers in dome-shaped clusters; Apocynum has tiny bell-shaped flowers in branched sprays.; vs Baccharis: Asclepias has milky sap and large distinctive flowers; Baccharis has clear sap and tiny fuzzy composite flowers.
Frequently asked questions
Is Asclepias solanoana native to California?
Yes. Asclepias solanoana is native to California (recorded as native).
When does Asclepias solanoana bloom?
Asclepias solanoana blooms Jun.
Where in California does Asclepias solanoana grow?
Asclepias solanoana occurs in Lake, Trinity, Colusa, Mendocino, Sonoma, Glenn, Shasta, Tehama and other counties, at elevations of 700-1600 m.
What plant family does Asclepias solanoana belong to?
Asclepias solanoana is in the Apocynaceae family, genus Asclepias.
Is Asclepias solanoana rare or endangered?
Asclepias solanoana carries California Rare Plant Rank 4.2, state rank S3.
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.