Holocarpha obconica

San joaquin tarweed

Family: Asteraceae · Type: annual · Native

San joaquin tarweed is a California native annual found in southern Sierra Nevada Foothills, northwestern San Joaquin Valley, eastern San Francisco Bay Area, and eastern South Coast Ranges in grassland habitats at elevations below 500 meters. Flowering from April to November, this plant produces yellow flowers with 4 to 9 ray flowers and 11 to 21 yellow to brownish disk flowers in flat-topped or panicle-like clusters. Growing 1 to 8 decimeters tall with slightly resinous stems that are not notably stalked-glandular, it has a distinctive branching structure. Its involucre is approximately obconic to spherical, with phyllaries featuring 5 to 15 pit-gland-tipped outgrowths and generally glabrous or minutely glandular surfaces. The plant's compact, clustered flower heads and resinous stems make it a characteristic element of California's grassland ecosystems.

Habitat: Grassland

Bloom period: Apr-Nov

Elevation: < 500 m

Bioregions: s SNF, nw SnJV, e SnFrB, e SCoRI.

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