Hymenophyllum tunbrigense (Linnaeus) J.E. Smith. Tunbridge Filmy Fern, Tunbridge Fern. Phen: Jun-Sep. Hab: Moist rock faces in an escarpment gorge with high rainfall. Dist: N. Mexico south through Central America to n. South America; w. South Carolina; West Indies (Jamaica and Hispaniola); w. Europe; Africa; Australia and New Zealand.

ID notes:H. tunbrigense somewhat resembles Vandenboschia boschiana. It differs from V. boschiana in having the sporangia not extending beyond the deeply 2-lobed involucre (as opposed to having the sporangia exserted beyond the slightly bilobed, funnelform involucre).

Origin/Endemic status: Native

Taxonomy Comments: Our circumscription of Hymenophyllum tunbrigense excludes taxa of s. South America sometimes included (see Larsen et al. 2017).

Other Comments: The occurrence of this filmy fern in the escarpment gorge of Eastatoe Creek and its tributaries (Pickens County, SC) is remarkable. Overall, H. tunbrigense is a "Gulf Stream plant," found in highly humid, climates in the West Indies, and the maritime west coast of the British Isles. This species may yet be found in NC in similarly rugged and humid escarpment gorges. Recent reports indicate that it may have been extirpated by severe droughts in the first decade of the 21st century.

Synonymy: = FNA2, K1, K3, K4, Meso1, W, Ebihara et al (2006), Larsen et al (2017); = Hymenophyllum tunbridgense – RAB, orthographic variant

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Heliophily: 1