Calflora, a 501c3 non-profit
Distribution by County   751    
Asclepias speciosa  Torr.
Showy milkweed
Asclepias speciosa is a perennial herb that is native to California, and also found elsewhere in North America and beyond.
Record Count by County

Alameda: 7 Humboldt: 31 Nevada: 29 Solano: 10
Alpine: 12 Inyo: 38 Orange: 4 Sonoma: 12
Amador: 17 Lake: 18 Placer: 17 Sutter: 6
Butte: 44 Lassen: 21 Plumas: 67 Tehama: 11
Calaveras: 5 Madera: 4 Sacramento: 14 Trinity: 68
Colusa: 15 Marin: 4 San Francisco: 1 Tulare: 5
Contra Costa: 14 Mariposa: 30 San Mateo: 2 Tuolumne: 17
Del Norte: 1 Mendocino: 17 Santa Clara: 4 Yolo: 16
El Dorado: 18 Modoc: 16 Shasta: 47 Yuba: 3
Fresno: 13 Mono: 34 Sierra: 30
Glenn: 8 Napa: 4 Siskiyou: 88

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2026. The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 06/13/2026).