Calochortus argillosus
Clay mariposa lily
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Family: Liliaceae · Type: Herb · Native
Calochortus argillosus (Clay mariposa lily) is a native California herb in the Liliaceae family, recognized by habitat specificity and petal markings are key.
Clay mariposa lily is a California native perennial found in western central California in hard clay habitats from volcanic or metamorphic rocks at elevations below 800 meters. Flowering from April to June, this lily produces white to purple flowers with a pale yellow background and a central red spot, with petals 20 to 40 millimeters long and a distinctive bell-shaped perianth. Growing 40 to 60 centimeters tall with a simple stem and small bulblets, the plant has basal leaves up to 30 centimeters long that wither during flowering. Its leaves become progressively reduced up the stem, with 1 to 4 erect flowers emerging from a somewhat umbel-like inflorescence. The plant produces an erect, lanceolate fruit 4 to 6 centimeters long, with distinctive purple, pink, or yellow-white anthers and a crescent-shaped nectary densely covered in short hairs.
Identification and appearance
Key characters: 19 sympatric species; habitat specificity and petal markings are key
Habitat and range
Habitat: Hard clay from volcanic or metamorphic rocks
Elevation: < 800 m
California counties: San Luis Obispo, Santa Barbara, Contra Costa, Alameda, San Mateo, Santa Clara, Napa, San Benito
Bloom period
Calochortus argillosus blooms Apr-Jun.
How to tell it apart
vs Clarkia: Calochortus has 6 stamens and grass-like leaves; Clarkia has 8 stamens and broad stem leaves.; vs Fritillaria: Calochortus flowers open upward/outward in cups; Fritillaria flowers hang downward like bells.; vs Thismia: Calochortus has green leaves and open flowers; Thismia is leafless with closed tubular flowers.; vs Eschscholzia: Calochortus has 6 petals and parallel-veined leaves; Eschscholzia has 4 petals and divided leaves.; vs Sidalcea: Calochortus has 6 petals and grass-like leaves; Sidalcea has 5 petals and rounded lobed leaves.
Frequently asked questions
Is Calochortus argillosus native to California?
Yes. Calochortus argillosus is native to California (recorded as native).
When does Calochortus argillosus bloom?
Calochortus argillosus blooms Apr-Jun.
Where in California does Calochortus argillosus grow?
Calochortus argillosus occurs in San Luis Obispo, Santa Barbara, Contra Costa, Alameda, San Mateo, Santa Clara, Napa, San Benito, at elevations of < 800 m.
What plant family does Calochortus argillosus belong to?
Calochortus argillosus is in the Liliaceae family, genus Calochortus.
What habitat does Calochortus argillosus grow in?
Calochortus argillosus grows in Hard clay from volcanic or metamorphic rocks.
Related species
Other California species in the same genus, family, or bioregion.
- Calochortus bruneaunis — Bruneau mariposa lily
- Calochortus catalinae — Catalina mariposa lily
- Calochortus clavatus — Club haired mariposa
- Calochortus clavatus var. avius — Pleasant valley mariposa lily
- Calochortus clavatus var. clavatus — Club-haired mariposa lily
- Calochortus clavatus var. gracilis — Slender mariposa lily
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.