Taxon Report

Asclepias solanoana Woodson

serpentine milkweed

Print Report


© 2009 Julie Kierstead Nelson

Taxon Summary

Asclepias solanoana, commonly known as serpentine milkweed, is a perennial herb in the Apocynaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, and Lower montane coniferous forest, growing at elevations from 230 to 1860 meters. Asclepias solanoana is ranked 4.2, Plants of Limited Distribution, A Watch List; Moderately threatened in California.

  Classification
Scientific Name:
 Asclepias solanoana Woodson
Common Name:
 serpentine milkweed
Family: Apocynaceae
Element Code: PDASC021R0
USDA Plants Symbol: ASSO
Synonyms/Other Names:

Ecology and Life History
Lifeform: perennial herb
Blooming Period: May-Jul(Aug) May-Jul(Aug)
Elevation: 230-1860 (755-6105)
General Habitats: Chaparral, Cismontane woodland, Lower montane coniferous forest
Microhabitat: Serpentine
Microhabitat Details:

Conservation Status
CA Rare Plant Rank: 4.2
Global Rank: G3
State Rank:
 S3
State List: None
Fed List: None
Other Status: SB_CalBG/RSABG
CRPR Changes:

Occurrence Data from the CNDDB
Total Occurrences: 0
Element Occurrence Ranks:
   Excellent (A) 0
   Good (B) 0
   Fair (C) 0
   Poor (D) 0
   None (X) 0
   Unknown (U) 0

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Colusa (COL), Glenn (GLE), Lake (LAK), Mendocino (MEN), Napa (NAP), Shasta (SHA), Sonoma (SON), Tehama (TEH), Trinity (TRI)
Quads: Name (Quad Code)
Benmore Canyon (3912215), Black Rock Mtn. (4012321), Bully Choop Mtn. (4012257), Cazadero (3812351), Crockett Peak (3912247), Detert Reservoir (3812265), Dubakella Mtn. (4012342), Fort Ross (3812352), Four Corners Rock (4012312), Fouts Springs (3912236), Gilmore Peak (3912235), Hall Ridge (3912276), Hough Springs (3912225), Hull Mountain (3912258), Jericho Valley (3812274), Jimtown (3812267), Knoxville (3812273), Leesville (3912224), Lewiston (4012267), Naufus Creek (4012343), North Yolla Bolly (4012228), Plaskett Ridge (3912268), Platina (4012238), Pony Buck Peak (4012331), Potato Hill (3912237), Riley Ridge (3912286), Smoky Creek (4012332), Solomon Peak (4012218), St. John Mtn. (3912246), The Geysers (3812277), Whispering Pines (3812276), Wilbur Springs (3912214), Wildwood (4012341), Wrights Ridge (4012311)

Threat List Data from the CNDDB

Threat List Total: 0
EOs with Threat Listed: Total EOs % of EOs
0 0 %

Notes
Not common where it occurs. 
Threats:
Threatened by grazing, vehicles, logging, mining, and geothermal development. Potentially threatened by renewable energy development.
Taxonomy:

Selected References

Proceedings of the American Academy of Arts and Sciences 10:76 (1874)
Asclepias solanoana profile for potential Species of Conservation Concern evaluation (2021). 
Madroño 24(3):159-177 (1977)
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 27 January 2025].