Plagiobothrys strictus
Calistoga popcornflower
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Family: Boraginaceae · Type: Herb · Native
Conservation status: CNPS 1B.1 · Endangered
Plagiobothrys strictus (Calistoga popcornflower) is a native California herb in the Boraginaceae family, recognized by nearly glabrous habit and hot spring habitat distinctive.
Calistoga popcornflower is a rare (CNPS 1B.1) California native annual found in southern North Coast Range Interior bioregion in northwestern Napa County, occurring in moist to wet sites near hot springs and vernal pools at elevations of 100 to 150 meters. Flowering from March to June, this plant produces white flowers with yellow appendages in delicate clusters approximately 4 to 6 millimeters in diameter. Growing with ascending to erect stems 10 to 40 centimeters tall, the plant is mostly smooth with fine hairs concentrated on the flower calyx. Its cauline leaves are elongated, with lower leaves reaching 4 to 9 centimeters in length. The fruit consists of small, flat nutlets with intricate surface textures featuring narrow, irregular cross-ribs and a linear scar near the base.
Identification and appearance
Key characters: 20 sympatric species - nearly glabrous habit and hot spring habitat distinctive
Habitat and range
Habitat: Moist to wet sites near hot springs, adjacent vernal pools, occasionally grassy swales
Elevation: 100-150 m
California counties: Napa, Lake, Sonoma
Bloom period
Plagiobothrys strictus blooms Mar-Jun.
Conservation status
CNPS 1B.1 · Endangered
How to tell it apart
vs Cryptantha: Seeds have a raised ridge down the inner face, not a groove like Cryptantha.; vs Pectocarya: Seeds lack the comb-like marginal barbs of Pectocarya; attachment scar is raised.; vs Myosotis: Flowers are smaller and more tubular; Myosotis has wider, flatter blue flowers with yellow centers.; vs Nemophila: Nemophila has much larger, showier blue-white flowers and broader leaves.; vs Leptosiphon: Leptosiphon has needle-like divided leaves; Plagiobothrys has simple narrow leaves.
Frequently asked questions
Is Plagiobothrys strictus native to California?
Yes. Plagiobothrys strictus is native to California (recorded as native).
When does Plagiobothrys strictus bloom?
Plagiobothrys strictus blooms Mar-Jun.
Where in California does Plagiobothrys strictus grow?
Plagiobothrys strictus occurs in Napa, Lake, Sonoma, at elevations of 100-150 m.
What plant family does Plagiobothrys strictus belong to?
Plagiobothrys strictus is in the Boraginaceae family, genus Plagiobothrys.
Is Plagiobothrys strictus rare or endangered?
Plagiobothrys strictus carries California Rare Plant Rank 1B.1, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
- Plagiobothrys tenellus — Pacific popcornflower
- Plagiobothrys tener — Slender popcornflower
- Plagiobothrys tener var. subglaber — Serpentine popcornflower
- Plagiobothrys tener var. tener — Slender popcornflower
- Plagiobothrys torreyi — High sierra popcornflower
- Plagiobothrys torreyi var. diffusus — Torrey's popcornflower
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
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.