The UC Davis Center for Plant Diversity has ca. 300,000 specimens. The collections are worldwide in scope, with strengths in the following geographic regions: California; Ecuador
; Baja California; the Antilles; the Pacific Islands; Mediterranean-climate regions. The following speciality areas are strong: range plants of California; vernal pool plants of California; alpine flora of western North America; poisonous and weedy plants of California; Euphorbiaceae; Poaceae; and the genera Quercus, Allium, Arctostaphylos, Atriplex, Capsicum, Clarkia, Eschscholzia, Lycianthes, Lycopersicon, Mimulus, Navarretia, Stephanomeria, Trifolium, Vitis.
The following collectors are well-represented in our collections: B. G. Baldwin, F. Bowcutt, CNPS, B. Crampton, E. Dean, J. Ditomaso, E. L. Ekman, K. Esau, R. W. Gankin, L. Gottlieb, G. Helmkamp, G. F. Hrusa, P. B. Kennedy, H. Kennedy, A. T. Leiser, J. Major, B. J. McCaskill, H. Olmo, R. Preston, W. W. Robbins, D. Sanchez-Mata, M. Sanderson, J. Shepard, A. Solomeshch, G. L. Stebbins, D. Taylor, J. M. Tucker, E. C. Twisselmann, G. L. Webster