XVI International Botanical Congess

Banksia (79 spp.) reaches its greatest diversity (63 spp.) in isolated southwestern Australia. This scleromorphic genus displays remarkable diversity in growth form, leaf shape, and leaf life-span, encompassing prostrate mats, shrubs, and trees up to 30 m in height. Closely-related Dryandra (92 spp.) is endemic to southwestern Australia, and several species are remarkably similar to certain Banksia. We analyzed sequence data from five cpDNA regions (rpl16 and trnL introns, and psbA/trnH, trnT/trnL, and trnL/trnF intergenic spacers) for 65 Banksia, 5 Dryandra, and 6 outgroups. Maximum parsimony indicated a basal dichotomy in Banksia, with monophyletic Dryandra embedded in one clade. That clade comprises mainly short-statured plants of dry regions with tough, serrate, long-lived leaves, the other, mainly tall plants of wetter regions with broad, shorter-lived leaves. The molecular data suggest biogeographic relationships quite different from those suggested by traditional taxonomy.