University of California, Davis herbarium collections are worldwide, with emphasis on California, North America, and neotropics (especially Ecuador and Baja California); Quercus, Fagaceae, and Arctostaphylos, Ericaceae of New World; Euphorbiaceae; Poaceae; Clarkia (Onagraceae); Lycianthes and Lycopersicon (Solanaceae); Stephanomeria and tarweed genera (Asteraceae); Navarretia (Polemoniaceae); Allium (Alliaceae); Trifolium (Fabaceae);Prunus (Rosaceae); Central Valley of California vernal pool species; weedy and poisonous species of California and Mediterranean-climate regions; range plants of California; alpine flora of western North America. Size of collection: 320,000 specimens, 50% from California.