Dryopteris expansa (Presl) Fraser-Jenkins & Jermy (Lichtgroene stekelvaren) ook in Nederland

Dryopteris expansa was recently discovered at two localities in the Netherlands (Havelterberg, prov. of Drenthe; Kuinderbos, prov. of Flevoland). Its diagnostic characters and taxonomic status are discussed. The taxon is morphologically very similar to D. dilatata and can only be identified by means of microscopical research (microglands c. 80 µm against c. 110 µm in D. dilatata; the diploid chromosome number whereas D. dilatata is a tetraploid). Nevertheless it is concluded that it must be regarded as a separate species. In the field D. expansa resembles Athyrium filix-femina in the light green colour and the soft texture of the lamina.