A palynological study of selected American members of Oxalis L.

[摘要] ENGLISH ABSTRACT:Oxalis L. has two centres of diversity, one in South-Central America and the other insouthern Africa. Previous palynological studies of southern Africa Oxalis revealedfour main pollen types, namely rugulate-reticulate, micro-rugulate-spinate, reticulateand supra-areolate (Dreyer 1996). The reticulate pollen type is further divided into 15subtypes, out of which five have a monotypic status. The supra-areolate pollen type isdivided into four subtypes based on exine structure. The reticulate pollen type is themost common pollen type within the South African members of Oxalis. The threeremaining main pollen types display more complex exine structures and are thereforeconsidered more derived than the reticulate pollen type.The present study assessed the pollen of 50 American Oxalis species with three mainobjectives: 1. To observe pollen type variations among American members of Oxalis,2. To compare pollen types from the two centres of diversity, and 3. To assess whichcentre of diversity house the palynologically more advanced species of Oxalis.Two main pollen types are recorded from the present study, namely reticulate andverrucate pollen types. The reticulate pollen type could be further divided into 11subtypes. Out of the 11 subtypes observed, nine also occur among South Africanmembers of Oxalis, while two types are only observed in the American members ofOxalis. The verrucate pollen type is found in a single American taxon and displays amore complex exine structure than the reticulate pollen type. In this study the reticulatepollen type proved to be the most common pollen type among the American membersof Oxalis. The South African members of Oxalis display more complex pollen typesthan the American members of the genus.

[发布机构] Stellenbosch University