Variation in Pseudorchis albida s.l. (Orchidaceae) and Carex capitata s.l. (Cyperaceae) : Morphology, genetic diversity, ecology and systematics

Sammanfattning: In the Scandinavian flora, several species-pairs where one member is an alpine species andthe other is a closely related lowland species, have been described. The aim of this studywas to investigate two such examples, viz. Pseudorchis albida s.s. and P. straminea(Orchidaceae) and Carex capitata s.s. and C. arctogena (Cyperaceae). Studies onmorphological, genetic (allozymes), and habitat demand variation were performed toaddress questions of differentiation, immigration history and taxonomic delimitations.Pseudorchis albida s.s. and P. straminea were well separated in morphological, geneticand ecological characteristics in Scandinavian material. However, a considerable overlap inmorphology was seen in European and North American herbarium material, which doesnot support a separation of the taxa at the species level. A separation at the subspecies level,P. albida ssp. albida and P. albida ssp. straminea, is suggested.Pseudorchis albida ssp. albida is today a threatened plant in Scandinavia. Studies on thehabitat demands showed that human disturbance is important, but that the plant does notrequire proper grassland management such as e.g. mowing. Furthermore, as evident fromordinations on vegetation data, this taxon will grow in quite a diversity of plantcommunities as long as the sward is kept short and as long as disturbances create bare soilfor its regeneration.Carex capitata s.s. and C. arctogena were well separated in morphological and genetic,but not in ecological characteristics, in Scandinavia. It is suggested that the taxa should betreated as separate species, C. capitata and C. arctogena.