Polymorphism of Potentilla tabernaemontani and related taxa on Gotland

Abstract

Potentilla tabernaemontani and P. cinerea are widely distributed in Europe and are linked together by hybrids. Sexual tetraploids occur, especially of P. cinerea in SE Europe. Biotypes from N Europe are high polyploids (2n=42 or more) and apomictic. On Gotland, a Swedish island in the Baltic sea, P. tabernaemontani shows a high degree of morphological variation, and hybrids with P. cinerea are not uncommon (Johansson 1905, Ark. Bot. 4: 1–18). Known chromosome numbers are 2n=42 (38 collections), 49 (11), 56 (6) and ±63 (3). Morphological variation and heteroploidy seem to be concentrated in NW Gotland. In other areas, hexaploids (2n=42) prevail, even where morphological variation is great (Faro). The polymorphism on Gotland exceeds that of most other parts of N Europe. Certain taxa seem in reappear in mountainous regions of Central and South Europe. More collections from Gotland and the Swedish mainland, as well as studies of material from other parts of Europe, are still needed for a taxonomic revision of this group.