''Hymenophyllum'' is a genus of
fern
The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...
s in the family
Hymenophyllaceae
The Hymenophyllaceae, the filmy ferns and bristle ferns, are a family of two to nine genera (depending on classification system) and about 650 known species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp pla ...
. 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
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. The ...
. 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.
Species
, World Ferns accepted the following extant species:
Extinct species include:
*†''
Hymenophyllum axsmithii'' (
Ypresian
In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...
,
Eocene Okanagan Highlands
The Eocene Okanagan Highlands or Eocene Okanogan Highlands are a series of Early Eocene geological formations which span a transect of British Columbia, Canada, and Washington state, United States. Known for a highly diverse and detailed plant ...
North America)
See also
* ''
Trichomanes'', the members of which are also called filmy ferns.
References
External links
Ferns of the genus ''Hymenophyllum'' observed in CornwallFilmy ferns
webpage of School of Biological Sciences, University of Auckland, New Zealand
{{Taxonbar, from=Q587453
Taxonomy articles created by Polbot
Fern genera
Long stubs with short prose