Hymenophyllaceae

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Hymenophyllaceae
Hymenophyllum tunbrigense in Luxembourg
Hymenophyllum tunbrigense in Luxembourg
Scientific classification
Kingdom: Plantae
Division: Pteridophyta
Class: Pteridopsida
Order: Hymenophyllales
Family: Hymenophyllaceae
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Genera

See text

The Hymenophyllaceae (filmy ferns and bristle ferns) is a family of seven genera and over 600 species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp places or to locations where they are wetted by spray from waterfalls or springs. A recent fossil find shows that ferns of Hymenophyllaceae have existed since at least the Upper Triassic.[1]

The great majority of the species are found in tropical rainforests, but some also occur in temperate rainforests (particularly New Zealand, with 25 species) and slightly drier forest regions. In Europe they are restricted to the Atlantic Ocean fringes of the continent, notably in the Azores, Ireland, and western Great Britain, but one species (Hymenophyllum tunbrigense) locally east to Luxembourg, while in North America, they are restricted to the humid eastern third of the continent.

They often appear as very dark green or even black clumps and may be mistaken for a robust moss or liverwort. The stem is thin and wiry and the fronds variously pinnate with a single strand ("nerve") of vascular tissue. In most species, the frond, apart from the vascular tissue, is only a single cell thickness, and they do not have any stomata; this makes the plants very susceptible to desiccation where a reliable water supply is not present. The sori are borne at the leaf margins at the end of the nerve. Individual plants may persist for many years.

[edit] Genera

Seven genera are accepted by the Germplasm Resources Information Network, but some older authorities (e.g. Copeland 1947) split the family up into as many as 34 different genera; several of these old genera are still accepted as subgenera (Flora of New Zealand 2004).

[edit] References

  1. ^ A filmy fern from the Upper Triassic of North Carolina (USA) - Axsmith et al. 88 (9): 1558 - American Journal of Botany
  • Ebihara, Atsushi; Dubuisson, Jean-Yves; Iwatsuki, Kunio; Hennequin, Sabine; Ito, Motomi: A Taxonomic Revision of Hymenophyllaceae. Blumea (journal) 51:2,2006 , pp. 221-280 [1]