Primula hendersonii
Mosquito bill(s), sailor caps, Sailor Caps
(c) Franz Xaver, some rights reserved (CC BY-SA) · licence
Family: Primulaceae · Type: Herb · Native
Primula hendersonii (Mosquito bill(s)) is a native California herb in the Primulaceae family, recognized by rice-like root bulblets and variable flower parts diagnostic.
Mosquito bill is a California native perennial found in the northwestern California, Cascade Range, Sierra Nevada, northern Sierra Nevada, Central Valley, San Francisco Bay Area, central western, and San Bernardine bioregions in shady sites at elevations below 1,900 meters. Flowering from March to July, this plant produces magenta to deep lavender or white flowers with distinctive corolla lobes 6 to 23 millimeters long. Growing 12 to 48 centimeters tall with glabrous to glandular-hairy stems, it develops unique rice-like bulblets at the flower roots. Its leaves range 2 to 16 centimeters long, with elliptic to ovate blades that narrow abruptly to the petiole and may have slight tooth edges. The plant bears an inflorescence of 3 to 17 flowers, with flower parts arranged in 4s or 5s, and features distinctive dark maroon to black anthers with transversely wrinkled connective tissue.
Identification and appearance
Key characters: 10 sympatric species; rice-like root bulblets and variable flower parts diagnostic
Habitat and range
Habitat: Generally in shady sites
Elevation: < 1900 m
California counties: Madera, Marin, San Mateo, Fresno, Sonoma, Santa Clara, Lake, Santa Cruz
Outside California: to southern British Columbia, Idaho
Bloom period
Primula hendersonii blooms Mar-Jul.
How to tell it apart
vs Lantana: Primula has backward-swept petals in umbrella-shaped clusters; Lantana has flat-faced flowers in dense rounded heads.; vs Pelargonium: Primula petals reflex dramatically backward with stamens forming a cone; Pelargonium petals spread forward with separate stamens.; vs Oenothera: Primula flowers have backward-swept petals in umbel clusters; Oenothera has bowl-shaped flowers opening singly or in spikes.; vs Cistanthe: Primula has backward-swept petals and cone-shaped stamens; Cistanthe has flat, rounded petals with separate stamens.; vs Kalanchoe: Primula is an herbaceous wildflower with reflexed petals; Kalanchoe is a succulent with tubular upright flowers.
Frequently asked questions
Is Primula hendersonii native to California?
Yes. Primula hendersonii is native to California (recorded as native).
When does Primula hendersonii bloom?
Primula hendersonii blooms Mar-Jul.
Where in California does Primula hendersonii grow?
Primula hendersonii occurs in Madera, Marin, San Mateo, Fresno, Sonoma, Santa Clara, Lake, Santa Cruz, at elevations of < 1900 m.
What plant family does Primula hendersonii belong to?
Primula hendersonii is in the Primulaceae family, genus Primula.
What habitat does Primula hendersonii grow in?
Primula hendersonii grows in Generally in shady sites.
Related species
Other California species in the same genus, family, or bioregion.
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.