(Kellogg) H.M. Hall 
The plant is found in California coastal sage and chaparral habitats, from 45–180 feet (14–55 m) in elevation. It is found in coastal dunes, chaparral hillsides, and exposed sea bluff habitats.
It is distributed on the coasts of: Southern California and the Channel Islands; the Central Coast region; San Francisco Bay Area; and in Mexico on the northwestern Baja California Peninsula and Guadalupe Island.
It is restricted to nearly frost-free habitats because its stem is succulent, being cold tolerant to around 25 degrees F. Storing water in this way makes the plants tolerant to drought but especially susceptible to frost.
The stem of Coreopsis gigantea is a trunk up to 1 metre (3.3 ft) tall, and 4–10 centimetres (1.6–3.9 in) in diameter. The plant can reach 4 feet (1.2 m) high by 2 feet (0.61 m) wide. It is summer deciduous, leaving a sculptural bare trunk and branches during the dry season.
Bright green leaves and flowers are on the top of the trunk, the rest of the trunk is bare.
The numerous flowers are yellow, daisy-like, 6–20 cm in diameter. It blooms in the spring and early summer.
Giant Coreopsis is cultivated as an ornamental plant by specialty nurseries. It is planted in native plant, drought tolerant, and wildlife gardens, and in natural landscaping and habitat restoration projects.
- California coastal sage and chaparral — a sub-ecoregion of the California chaparral and woodlands ecoregion.
- Natural history of the California chaparral and woodlands
- ITIS 37133
- Jepson eFlora: Leptosyne gigantea . accessed 2.28.2015
- The Plant List, Coreopsis gigantea (Kellogg) H.M.Hall
- United States Department of Agriculture plants profile: Coreopsis gigantea . accessed 2.28.2015
- Calflora taxon report, University of California: Leptosyne gigantea . accessed 2.28.2015
- Theodore Payne Foundation California Natives Wiki: Coreopsis gigantea (Giant Coreopsis)
- Las Pilitas Horticulture Database: Coreopsis gigantea, Giant Coreopsis
- San Marcos Growers database: Coreopsis gigantea
- San Francisco Chronicle: "Coreopsis is supersize on the Channel Islands" — Sullivan, R. & J. Eaton; October 8, 2008.
- UC— Jepson Manual treatment for Leptosyne gigantea (Coreopsis gigantea)
- United States Department of Agriculture Plants Profile for Coreopsis gigantea (giant coreopsis)
- Leptosyne gigantea (Coreopsis gigantea) — Calphotos Photo gallery, University of California
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