Flora of the Southeastern United States

Hymenophyllum cordobense (Hieronymus) C. Larsen & Arana. Common name: American Tunbridge Filmy Fern, Cordoba Fern. Phenology: Jun-Sep. Habitat: Moist rock faces in an escarpment gorge with high rainfall. Distribution: N. Mexico south through Central America to n. South America; w. South Carolina; West Indies (Jamaica and Hispaniola). Old World material belongs to H. tunbrigense.

ID notes: H. cordobense 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: The identity of the very rare North American "Hymenophyllum tunbrigense" needs modern study in the context of the breaking up of the former concept of a cosmopolitan H. tunbrigense with disjunct populations scattered around the World (Larsen et al. 2017; Galeotti et al. 2023). It seems to be more likely that our North American material is disjunct from Mexico, Central America, and South America (than from w. Europe), and it is here provisionally placed in H. cordobense (POWO 2024; Larsen et al. 2017; Gonzatti et al. 2023), but may ultimately be found to represent a different segregate in this complex.

Other Comments: The occurrence of this filmy fern in the escarpment gorge of Eastatoe Creek and its tributaries (Pickens County, SC) is remarkable. This species may yet be found in NC in similarly rugged and humid escarpment gorges. While it was feared that drought may have threatened this disjunction with extirpation, recent reports indicate it is faring well (K. Bradley, pers. comm.; 2025).

Synonymy ⓘ: = POWO, Larsen et al (2017); Hymenophyllum tunbrigense (Linnaeus) J.E. Smith var. cordobense Hieron.; Trichomanes tunbrigense L.; = Hymenophyllum tunbridgense (Linnaeus) J.E. Smith — RAB, orthographic variant; = n/a — Sf; < Hymenophyllum tunbrigense (Linnaeus) J.E. Smith — FNA2, K1, K4, Meso1, NS, W, Ebihara et al (2006), Larsen et al (2017). Basionym: Hymenophyllum tunbrigense (Linnaeus) J.E. Smith var. cordobense Hieron. 1896

Links to other floras: < Hymenophyllum tunbrigense - FNA2

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Heliophily ⓘ: 1