Ezosciadium (Apiaceae): a taxonomic revision of yet another early diverging South African apioid genus

The hitherto poorly known Cape endemic genus Ezosciadium (Apiaceae) is revised. This genus is highly distinctive and can be distinguished from other annual genera of the region by its pilose vegetative and reproductive organs, the sessile compound umbels with conspicuously unequal rays, the non-inflexed petal tips, the relatively small, highly-inflexed stamens which appear almost sessile, and the prominent carpophores which persist on the plant. The fruit are unusual in the presence of druse crystals around the carpophore and tanniniferous substances in the epidermal cells of the ribs. The phylogenetic position of the genus within the subfamily Apioideae was assessed using rbcL, rps16 intron (2 new accessions) and nrITS (1 new accession) sequence data. Ezosciadium capense was found to form part of an early diverging lineage within the subfamily, sister group to the Annesorhiza clade and possibly also closely related to the genera Molopospermum and Astydamia. A comprehensive taxonomic revision, including typification, detailed descriptions, geographical range and illustrations, is presented.