Flower profile
Narrowleaf milkweed
Asclepias fascicularis
Narrowleaf milkweed (Asclepias fascicularis) is a flowering plant in the Apocynaceae family, native in the lower 48 states, blooming mostly June–August across the U.S.
Narrowleaf milkweed is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 2 states, and across the U.S. it's most often seen in bloom in June–August.
*iNaturalist research-grade observations, as of October 17, 2026.
On our lists for: California, Nevada
Quick look
Asclepias fascicularis is a species of milkweed known by the common names narrowleaf milkweed and Mexican whorled milkweed. It is a perennial herb that grows in a variety of habitats.
- It belongs to the Apocynaceae family. iNaturalist
- USDA PLANTS describes it as an herb (forb) with a perennial life cycle. USDA PLANTS
- USDA PLANTS lists it as native in the lower 48 states and records it in 6 states. USDA PLANTS
- NatureServe lists it as native to California and Nevada. NatureServe
- In California, most iNaturalist sightings of it in flower come in June–August. iNaturalist
- In Nevada, most iNaturalist sightings of it in flower come in June–August. iNaturalist
- iNaturalist has 14,702 research-grade sightings of it in California, ranking #48 among the 178 flowers on our California list. iNaturalist
- iNaturalist has 1,273 research-grade sightings of it in Nevada, ranking #21 among the 132 flowers on our Nevada list. iNaturalist
When does it bloom?
Bloom time in the 2 states whose Bloomipedia list includes it
| State | Type | Peak bloom | Sightings* |
|---|---|---|---|
| California | Native | June–August | 14,702 |
| Nevada | Native | June–August | 1,273 |
Conservation status
- Federal (U.S. ESA)
- Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
- NatureServe global
- G5 Secure worldwide. NatureServe
- California
- Not listed Not on California state-listed endangered, threatened and rare plants (14 CCR § 670.2), per CDFW's CNDDB list (July 2026). NatureServe: SNR, not yet ranked in California. CNDDB listed plants (July 2026)
- Nevada
- Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: S4, apparently secure in Nevada. NAC 527.010
- Rare elsewhere
- Other states where NatureServe ranks it rare or missing: UT (S1). (S1 critically imperiled, S2 imperiled, SH possibly extirpated, SX presumed extirpated.)
Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.
Can you eat it?
None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.
ASPCA's entry “Milkweed” (Asclepias species), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Vomiting, profound depression, weakness, anorexia, and diarrhea are common; may be followed by seizures, difficulty breathing, rapid, weak pulse, dilated pupils, kidney or liver failure, coma… ASPCA
🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.
Where does it grow?
USDA PLANTS records narrowleaf milkweed in 6 states.
recorded by USDA PLANTS on our state lists not recorded
See the full list of states
California, Idaho, Nevada, Oregon, Utah, Washington.
California counties with USDA records: Alameda, Alpine, Amador, Butte, Calaveras, Colusa, Contra Costa, Fresno, Glenn, Humboldt, Inyo, Kern, Lake, Lassen, Los Angeles, Madera, Marin, Mariposa, Mendocino, Merced, Modoc, Mono, Monterey, Napa, Nevada, Orange, Plumas, Riverside, Sacramento, San Benito, San Bernardino, San Diego, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Siskiyou, Solano, Sonoma, Stanislaus, Tehama, Trinity, Tulare, Tuolumne, Ventura, Yolo.
Nevada counties with USDA records: Carson City, Churchill, Douglas, Elko, Lander, Lyon, Mineral, Nye, Pershing, Storey, Washoe.
Names, range and relatives
County records: USDA PLANTS lists it in 99 counties across 6 states; the most are in California (49), Oregon (19), Idaho (12).
Other Asclepias on Bloomipedia (16): Common milkweed, Butterfly milkweed, Swamp milkweed, Green antelopehorns, Antelopehorn milkweed, Showy milkweed, Green comet milkweed, Zizotes milkweed, Tropical milkweed, Redring milkweed.
More from the Apocynaceae family (28 on Bloomipedia; most observed first): Lesser periwinkle, Greater periwinkle, Spreading dogbane, Pearl milkweed, Madagascar periwinkle, Honey-vine climbing milkweed, Hartweg's climbing milkweed, Oleander.
More California flowers
Sources
- USDA, NRCS. PLANTS Database, profile ASFA.
- iNaturalist, Asclepias fascicularis: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
- Wikipedia, Asclepias fascicularis (lead quoted under CC BY-SA 4.0).
- California: California state-listed endangered, threatened and rare plants (14 CCR § 670.2), per CDFW's CNDDB list (July 2026).
- California: California noxious weed species (3 CCR § 4500).
- Nevada: Nevada fully protected plants, critically endangered (NAC 527.010).
- Nevada: Nevada noxious weeds (NAC 555.010).
- USFWS, ECOS species database (ESA listing check), October 17, 2026.
- NatureServe Explorer, Asclepias fascicularis (global and state ranks).
- Edibility and toxicity: ASPCA.
- Photo: Dominic Gentilcore via iNaturalist · CC BY 4.0 · resized.