Format: ORAL

Michael G. Simpson1, C. Matt Guilliams2,Kristen E. Hasenstab-Lehman2, Makenzie E. Mabry3

1 San Diego State University, San Diego, USA 2 Santa Barbara Botanic Garden, Santa Barbara, USA 3 University of Florida, Gainesville, USA

Subtribe Amsinckiinae, colloquially known as the popcorn flowers, is currently recognized with 17 genera and approximately 302 species. The subtribe exhibits a remarkable diversity of form and is one of the most taxon-rich groups of family Boraginaceae. Several new species in the subtribe have been discovered in the past five years, with more yet to be described. Analyses of new chloroplast DNA and ddRadSeq sequence data resolve some past ambiguities and confirm generally strong support for the monophyly of the 17 genera and of a separate group of Cryptantha species termed the Maritimae clade. We report the status of resolving backbone interrelationships among these major clades, which are often poorly resolved. We summarize major evolutionary shifts in the Amsinckiinae in plant duration, leaf size, fruit morphology, and reproductive biology. Long-distance dispersals within the subtribe occurred a minimum of 18 times, each resulting in an American amphitropic disjunction. Based on sequence data and comparative morphology, we now expand membership of the Maritimae clade to include up to 7 North American and 12 South American species, the latter resulting from evolutionary divergence following a single long-distance dispersal event. Finally, we present evidence that the Maritimae clade is inclusive of a monotypic genus previously not confirmed as a member of the subtribe, and we evaluate whether the Maritimae clade might best be treated as a separate genus of the popcorn flowers.