South African Journal of Botany 2004, 70(3): 393–406 Copyright © NISC Pty Ltd Printed in South Africa — All rights reserved SOUTH AFRICAN JOURNAL OF BOTANY ISSN 0254–6299 Circumscription of Apiaceae tribe Oenantheae TM Hardway1, K Spalik2, MF Watson3, DS Katz-Downie1 and SR Downie1* 1 Department of Plant Biology, University of Illinois, Urbana 61801, United States of America 2 Department of Plant Systematics and Geography, Warsaw University, Aleje Ujazdowskie 4, 00-478 Warsaw, Poland 3 Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland, United Kingdom * Corresponding author, email:
[email protected] Received 18 August 2003, accepted in revised form 17 November 2003 Previous molecular systematic investigations into the Sium and Trepocarpus. Relationships inferred from higher-level relationships of Apiaceae subfamily phylogenetic analyses of nuclear rDNA ITS sequences Apioideae have revealed a strongly supported clade from 64 accessions representing all 17 genera reveal recognised as tribe Oenantheae Dumort. These plants that four genera are not monophyletic. Bifora and may have clusters of fibrous or tuberous-thickened Cryptotaenia have members that fall outside of the tribe; roots, corky-thickened fruits, and other adaptations for Berula and Sium each comprise two or more lineages existence in wet or aquatic habitats. In some species, within Oenantheae. The St Helena endemics, Sium the leaves may be finely dissected or linear-septate and bracteatum and S. burchellii, ally with African Berula much reduced. We have initiated collaborative studies erecta; this clade is sister to the African endemic to produce a comprehensive estimate of phylogeny of species Sium repandum and Afrocarum imbricatum, the tribe, but such investigations are thwarted because and this entire group is allied closely with north tem- information on the composition of the tribe is lacking.