Karyological investigations on the South-African invasive Oxalis pes-caprae L. (Oxalidaceae) in native and invaded areas, with special focus on Italy.

Results are given and discussed of karyological investigations on wild (19) and cultivated (2) populations of the invasive South African geophyte Oxalis pes-caprae L. from 21 different localities (Italy 16; Switzerland 1; Morocco 1; South Africa 3). Plants from naturalized populations growing wild in Italy and Morocco proved to always be pentaploid (2n = 35), with small, metacentric or slightly sub-metacentric chromosomes. In plants cultivated in the Botanical Garden in Rome, both pentaploid and tetraploid (2n = 28) numbers were found, the latter being the first record of tetraploid plants from Italy. All plants from South African wild populations included tetraploid plants; in one population (Kirstenbosch) pentaploid plants were also detected. It is suggested that pentaploid plants are possibly more widespread in the species’ native area than is currently believed.