EVOLUTION, SYSTEMATICS, AND TERPENE RELATIONSHIPS OF SALVIA SECTION AUDIBERTIA (CALIFORNIA)

Since the last revision of Salvia section Audibertia by Epling in 1938 a new species has been described. Increased distributional information and improved understanding of global phytogeography resulted in the need for a revision of this section depicting more accurately the interrelationships and evolutionary history.Detailed morphological and anatomical studies, including S.E.M. of pollen and trichomes, plus extensive chemical analysis of mono- and sesquiterpenes were conducted.As a result of this study, the section Audibertia has been reorganized to include two sections, Audibertia and Echinosphace, the former with three subsections and ten series, the latter with two subsections and four series. Outgroup analysis suggests an evolutionary history for these species having Afro-Laurasian ancestral ties, rather than the previous assumptions of a Mexican origin.Morphological examinations revealed heterostyly in S. brandegei, a breeding system previously undescribed in zygomorphic dicotyledenous angiosperm. A major range extension of S. leucophylla into Baja California was documented.For this study more than 1500 plants representing over 85 populations of the 19 Audibertia species plus relatives were grown in a uniform garden at the University of California at Riverside. In addition, more than 2000 herbarium voucher specimens were studied.Mono- and sesquiterpene analysis revealed chemotypes in S. mellifera and S. apiana, and inferred chemotypes in S. columbariae and S. brandegei. Intrapopulational analysis reflecting outcrossing rates within populations and species is discussed. Terpene analysis further indicated that habitat and environment may play an active role in terpene selection. Thus, care should be taken in inferring phylogenetic relationships within a plant taxon which are based primarily on terpene expression.