The Fern GenusPolystichum(Dryopteridaceae) in Costa Rica1

Costa Rica is home to 12 species of the taxonomically challenging fern genus Polystichum, including three allopolyploids. This study provides a taxonomic identification guide for these species, focusing on key morphological characters such as petiole and pinna-rachis scales, ultimate segment shape, and indusium. The research also evaluates the distribution patterns of the genus in the Neotropics, revealing that while five species are widespread across Tropical America, two extend to the southern range limits, and three—including two allopolyploids—are confined to Costa Rica and Panama. Additionally, the study lectotypifies three names: P. aculeatum var. flavidum, P. nudicaule, and P. opacum. The genus is predominantly found in high-elevation rainforests and páramos of the Cerro de Talamanca, highlighting its ecological preference for wetter montane regions.

Barrington, D. S. (2012). The Fern GenusPolystichum(Dryopteridaceae) in Costa Rica¹. Annals of the Missouri Botanical Garden, 98(4), 431–446. https://doi.org/10.3417/2011051