The Oldest Record ofPolypodium interjectumin Sweden, with Notes on the Variability ofP. vulgare

Abstract

The variability of Polypodium vulgare s. lato (Polypodiaceae) in the Nordic countries was studied. An unpublished herbarium record of P. interjectum from Sweden (province Scania) was confirmed. The respective specimen, originally classified as P. vulgare, was later re-identified as P. interjectum but that remained unnoticed in the literature. Here, the first find of the species in Sweden is reported. Another Swedish specimen with a similar identification history was found to be originally correctly identified. Field work and screening of herbarium material did not yield specimens of P. interjectum from Finland. Instead, the Finnish P. vulgare displayed unexpectedly much previously unknown variability, including four types of rhizome taste and the presence, even of two kinds, of sporangiasters in part of the material. Sensory observations also suggest that the rhizome of P. vulgare emits the volatile compound 2-nonenal. As some of the variability noted is often diagnostic at the species level in the P. vulgare aggregate elsewhere, the existence of cryptic species within the Nordic P. vulgare cannot be totally ruled out. No hybrid plants with heterogeneous spores were detected.