Hymenophyllum

Hymenophyllum
A plate featuring Hymenophyllum species from The Ferns of Great Britain and Ireland
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Polypodiopsida/Pteridopsida (disputed)
Order:	Hymenophyllales
Family:	Hymenophyllaceae
Subfamily:	Hymenophylloideae Burnett
Genus:	Hymenophyllum Sm.

Hymenophyllum is a genus of ferns in the family Hymenophyllaceae. Its name means "membranous leaf", referring to the very thin translucent tissue of the fronds, which gives rise to the common name filmy fern for this and other thin-leaved ferns. The leaves are generally only one cell thick and lack stomata, making them vulnerable to desiccation. Consequently, they are found only in very humid areas, such as in moist forests and among sheltered rocks. They are small and easy to overlook.

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Wikipedia