Eriastrum filifolium
Thread-leaved woolly-star
(c) Sula Vanderplank, some rights reserved (CC BY) · licence
Family: Polemoniaceae · Type: Herb · Native
Eriastrum filifolium (Thread-leaved woolly-star) is a native California herb in the Polemoniaceae family, recognized by thread-like leaves and pale yellow tubes with blue lobes distinctive.
Thread-leaved woolly-star is a California native annual found in northwestern Santa Barbara County and southwestern California in wash bottoms, chaparral, coastal sagebrush scrub, and grassland areas at elevations of 35 to 940 meters. Flowering from April to May, this plant produces pale yellow to white flowers with distinctive light- to royal-blue or occasionally lavender corolla lobes. Growing 3 to 40 centimeters tall with erect to ascending stems that are lightly woolly and sometimes branched from the base, it develops thread-like leaves that often turn red-brown with age. Its delicate leaves are typically 10 to 35 millimeters long, thread-like or occasionally 5-lobed, with a sparse woolly texture. The fruit is a small capsule 4 to 5 millimeters long, containing 3 to 5 angular tan to light brown seeds.
Identification and appearance
Key characters: 17 sympatric species; thread-like leaves and pale yellow tubes with blue lobes distinctive
Habitat and range
Habitat: Wash bottoms, floodplains, ditches, slopes, ridges, disturbed areas, in chaparral, coastal sagebrush scrub, grassland
Elevation: 35-940 m
California counties: Los Angeles, San Diego, Riverside, Santa Barbara, Inyo, Kern, Ventura, Alpine, Mono
Outside California: Baja California
Bloom period
Eriastrum filifolium blooms Apr-May.
How to tell it apart
vs Navarretia: Eriastrum has fluffy white woolly hairs; Navarretia has spine-tipped bracts and leaves without woolly hairs.; vs Gilia: Eriastrum flower clusters are densely woolly-hairy; Gilia flower clusters lack woolly hairs.; vs Loeseliastrum: Eriastrum has woolly tufted hairs and radial flowers; Loeseliastrum has simple hairs and bilateral flowers.; vs Langloisia: Eriastrum has woolly tufted white hairs; Langloisia has stiff branched bristly hairs.; vs Petalonyx: Eriastrum has opposite lobed leaves in Polemoniaceae; Petalonyx has alternate simple leaves in Loasaceae.
Frequently asked questions
Is Eriastrum filifolium native to California?
Yes. Eriastrum filifolium is native to California (recorded as native).
When does Eriastrum filifolium bloom?
Eriastrum filifolium blooms Apr-May.
Where in California does Eriastrum filifolium grow?
Eriastrum filifolium occurs in Los Angeles, San Diego, Riverside, Santa Barbara, Inyo, Kern, Ventura, Alpine and other counties, at elevations of 35-940 m.
What plant family does Eriastrum filifolium belong to?
Eriastrum filifolium is in the Polemoniaceae family, genus Eriastrum.
What habitat does Eriastrum filifolium grow in?
Eriastrum filifolium grows in Wash bottoms, floodplains, ditches, slopes, ridges, disturbed areas, in chaparral, coastal sagebrush scrub, grassland.
Related species
Other California species in the same genus, family, or bioregion.
- Eriastrum harwoodii — Harwood's woolly-star
- Eriastrum hooveri — Hoover's woolly-star
- Eriastrum luteum — Yellow woolly-star
- Eriastrum pluriflorum — Many-flowered woolly-star
- Eriastrum pluriflorum subsp. albifaux — White-throated woolly-star
- Eriastrum pluriflorum subsp. pluriflorum — Many-flowered woolly-star
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.