Tetrapteron graciliflorum

Hill sun cup

Family: Onagraceae · Type: annual · Native

Hill sun cup is a California native annual found in northwestern California, Cascade Range, Sierra Nevada foothills, Central Valley, central western California, and Transverse Ranges in open or shrubby slopes, grasslands, and oak and Joshua-tree woodlands at elevations below 800 meters. Flowering from March to April, this plant produces small flowers with petals that are roughly equal to its anthers, capable of self-pollination or cross-pollination. Growing with slender stems up to 25 millimeters tall that are not swollen or peeling, it has a delicate, low-growing form. Its leaves range from 10 to 98 millimeters long, appearing entire or with very subtle, minute serrations. The fruit is a distinctive 4 to 8 millimeters long, featuring four angles or wings near its tip, with a leathery texture that splits open slowly.

Habitat: Open or shrubby slopes, generally clay soils, grassland, oak and Joshua-tree woodland

Bloom period: Mar-Apr

Elevation: < 800 m

Bioregions: NW, CaR, SNF, GV, CW, WTR

California counties: Kern, Los Angeles, Napa, San Luis Obispo, Glenn, Lassen, Butte, Sutter, Tehama, Colusa, Siskiyou, San Benito, Humboldt, Fresno, Tulare, Santa Clara, Contra Costa, Merced, Mendocino, Monterey, Stanislaus, Alameda, Shasta, Placer, San Joaquin, Lake, Yolo, Sonoma, Santa Barbara, Ventura, Marin

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.