Flower profile

Narrowleaf milkweed

Asclepias fascicularis

Native in the lower 48

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 May–September.

6states

2of our state lists

17,099U.S. sightings*

*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.
From Wikipedia's article Asclepias fascicularis, CC BY-SA 4.0.

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 May–September. ^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 110 flowers on our California list. ^iNaturalist
iNaturalist has 1,273 research-grade sightings of it in Nevada, ranking #21 among the 110 flowers on our Nevada list. ^iNaturalist

Narrowleaf milkweed gift ideas

Handmade narrowleaf milkweed gifts from independent makers.

🌱 Sample spot. Handmade gift picks from independent shops will appear here once our shop partnership is approved. These cards are placeholders, not real products.

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Narrowleaf milkweed art print
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When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (3,111 records)

Bloom time in each of our 2 states

State	Type	Peak bloom	Sightings*
California	Native	May–September	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?

For peopleNot well documented

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.

For petsToxic to dogs, cats and horses

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.

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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.

More California flowers

Greater periwinkle

Vinca major

Introduced

🌼 Blooms in CA: January–June

Showy milkweed

Asclepias speciosa

Native

🌼 Blooms: June–August

Rush milkweed

Asclepias subulata

Native

🌼 Blooms: January–December

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.