Spinulose Wood Fern

Description

Dryopteris carthusiana is a species of fern native to damp forests throughout the Holarctic Kingdom. It is known as the narrow buckler-fern in the United Kingdom,and as the spinulose woodfern in North America. It is a tetraploid of hybrid origin, one parent being Dryopteris intermedia, known in North America as the intermediate wood fern, and an unknown, apparently extinct species dubbed Dryopteris semicristata, which is also the presumed parent of the hybrid-origin Dryopteris cristata. This fern is often confused with several other wood fern species, including D. intermedia, D. campyloptera, and D. expansa. It especially extensively shares the range of D. intermedia, but the two may be distinguished by the innermost pinnule on the bottom side of the bottom pinna: this pinnule is longer than the adjacent pinnules in D. carthusiana, but shorter or even in D. intermedia. D. carthusiana is a sub-evergreen species, its fronds surviving mild winters but dying back in harsh winters. Dryopteris commonly called the wood ferns, male ferns (referring in particular to Dryopteris filix-mas), or buckler ferns, is a fern genus in the family Dryopteridaceae, subfamily Dryopteridoideae, according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). There are about 300-400 species in the genus. The species are distributed in Asia, the Americas, Europe, Africa, and the Pacific islands, with the highest diversity in eastern Asia. It is placed in the family Dryopteridaceae, subfamily Dryopteridoideae, according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Many of the species have stout, slowly creeping rootstocks that form a crown, with a vase-like ring of fronds. The sori are round, with a peltate indusium. The stipes have prominent scales. Hybridization and polyploidy are well-known phenomena in this group, with many species formed via these processes. The North American Dryopteris hybrid complex is a well-known example of speciation via allopolyploid hybridization. The genus has a large number of species. The PPG I classification suggested there were about 400 species; as of February 2020, the Checklist of Ferns and Lycophytes of the World listed 328 species and 83 hybrids. Some genera sunk into Dryopteris, such as Dryopsis, Stenolepia and Nothoperanema, are distinguished by other sources.