New Combinations in Californian Grindelia (Compositae: Astereae)

Abstract

As treated for the forthcoming revision of the Jepson Manual of the Flowering Plants of California, there are six species of Grindelia in California. Hybridization among them is common, and is apparently the reason for proliferation of epithets in the group. Thorough study of over 6,000 specimens (including the types for all epithets in- volved) from 34 herbaria has necessitated the rec- ognition of several new combinations, and synony- mization of many others. Grindelia Willd. (Compositae: Astereae) is even more highly variable in California than elsewhere in its range in the western United States, Mexico, and South America. Several of the taxa apparently hy- bridize freely when they are in contact; this is the primary source of the taxonomic confusion that has led to the erection of more than 60 epithets for taxa of California alone. Though a more thorough dis- cussion of the systematics of this group will be pub- lished elsewhere, it is necessary now to provide new combinations that may be used in a treatment of Grindelia for the forthcoming revision of the Jepson Manual of the Flowering Plants of California. Based on examination of the types for all the bas- ionyms involved and over 6,000 specimens from 34 herbaria, I have come to the conclusion that it is most reasonable to recognize six species for the state. One of these, Grindelia squarrosa (Pursh) Dunal, represented in California by G. squarrosa var. ser- rulata (Rydberg) Steyermark, is probably adventive, and occurs in only a few localities. It is not a major player in the hybridization reticula, and is easily distinguished from other California specimens by its bluntly dentate-serrulate leaf margins. Another species, Grindeliafraxino-pratensis Re- veal & Beatley, is known only from the Ash Mead- ows area of Nye Co., Nevada, and Inyo Co., Cali- fornia, and is not involved in hybridizations with other taxa. The involucres of G. fraxino-pratensis are broadly turbinate; all other grindelias in Cali- fornia have broadly campanulate to hemispheric heads. Grindelia nana Nutt. is found in northeastern