Taxonomic assessment of O. furcillata (Oxalidaceae)

[摘要] The family Oxalidaceae has a worldwide distribution, but is most common in tropicaland subtropical regions. Oxalis L. is the largest genus of the family comprising ca.800 of the 900 species. Oxalis species are annual or perennial herbs or rarelysubshrubs or trees. The current study assesses on the taxonomic placement ofO. furcillata Salter. Currently this species, comprising two varieties, O. furcillata var.furcillata and O. furcillata var. caulescens Salter, is placed in section Foveolatae.Members of this section have endospermous seeds and fleshy leaflets. However, bothin terms of leaf morphological and seed characters the two varieties of this speciesappear to be misplaced within this section. In addition O. furcillata var. caulescenshas a unique pollen type, different from both the typical variety and the rest of thesection. Both lines of evidence thus suggest that O. furcillata var. caulescens may bemisplaced within this section. The present study thus sets out to assess the placementof O. furcillata in general, and the placement of O. furcillata var. caulescens inparticular. A multi-disciplinary approach was followed, which included analyses ofmacro-morphological (including LM and SEM analyses), biogeographical andpalynological characters. The variability of quantitative characters was assessed usingthe STATISTICA 6.0 software package. Leaf dimensions, plant height, bulb length,petiole length and palynology showed sufficient differences between the two taxa toconfirm the separate identity of these two varieties as separate species. O. furcillatavar. caulescens was thus raised to specific status as O. caulescens (Salter) Bissiengou.The results suggest two different options in terms of the taxonomic placement of thespecies O. furcillata and O. caulescens. They can either remain in section Foveolatae,best placed near O. senecta and O. densa or may moved to the highly variable sectionLatifoliolatae. But retaining them within the section Foveolatae appeared to be thebetter alternative. The correct position will be established both through furthermorphological analyses and correlation to the trnL-F and ITS sequence-basedphylogeny of the southern African members of Oxalis.

[发布机构] Stellenbosch University