Systematic significance of bulb morphology of the Southern African members of Oxalis L. (Oxalidaceae)

[摘要] ENGLISH ABSTRACT:The systematics of the southern African members of the genus Oxalis L. (Oxalidaceae) is in astate of flux. The bulbs of these species contain potential taxonomically important charactersand therefore require detailed study (Salter, 1944). A pilot study assessed the homology ofbulbs among southern African Oxalis species (Gebregziabher, 2001), and found that they areall homologous structures. This pilot study also emphasized the range of potentiallyinformative characters from different bulb parts.The aim of the present study was to assess the taxonomic significance of bulb morphology inselected southern African Oxalis species. As far as possible, efforts were made to representboth the taxonomic (Salter, 1944) and palynological diversity (Dreyer, 1996) present in thegenus.Detailed bulb morphological studies of 30 species of southern African Oxalis species revealed41 potentially informative characters. Different bulb-types were identified based on thesecharacters. Bulb-type affinities of taxa included in this study, as well as bulb descriptionsfrom the pilot study (Gebregziabher, 2001), were discussed. Comparison with the currenttaxonomic classification (Salter, 1944), palynological classification (Dreyer, 1996) and apreliminary phylogeny based on the non-coding plastid trnL-trnF DNA region (Oberlander,2003), were also made. Bulb morphology conflicted with the current taxonomic classification(Salter, 1944), but showed greater congruence with both the palynological groupings and thetrnL-trnF based phylogeny.Based on this study, bulb morphology is found to be taxonomically significant. Furtherstudies on the bulb morphology and anatomy of southern African Oxalis species are merited.Key words: bulb morphology, Oxalis, informative characters, basal plates, fleshy leaves,tunics

[发布机构] Stellenbosch University