D. glomerata growing in a dry bed of East Fork Coyote Creek near Los Cruzeros, CA. (Copyright Lee Dittmann, used with permission from www.coestatepark.com)
The Datiscaceae currently is classified in the order Cucurbitales (APG, 1998). Molecular phylogenetic work places only the genus Datisca in the Datiscaceae with two species. Both Datisca species bear root nodules (Swensen et al., 1998; Swensen et al., 1994).
The two species of Datisca, D. cannabina L. and D. glomerata (Presl.) Baill., are adapted to Mediterranean climates and have an interesting distribution. D. cannabina is found in the Mediterranean basin and D. glomerata is found on the western slope of the Sierra Nevada from northern California to Baja California (Swensen, et al., 1994). Plants in California and the Mediterranean basin are known to have some taxonomic affinities since North America and Europe have been separated only since the Tertiary (Solbrig et al., 1977). Studies on Datisca phylogeny indicate that geographic subdivision rather than long distance dispersal accounts for the present day distribution (Swensen et al., 1998). Mediterranean climates have been established only since the Pleistocene so it seems likely that each species adapted separately to the Mediterranean climate instead of an ancestor to the two species being pre-adapted to the Mediterranean climate (Solbrig, et al., 1977).