5. Hymenophyllum J. Smith, Mém. Acad. Roy. Sci. (Turin). 5: 418. 1793.
膜蕨属 mo jue shu
Mecodium C. Presl ex Copeland; Meringium C. Presl; Microtrichomanes (Mettenius) Copeland; Pleuromanes C. Presl; Trichomanes sect. Microtrichomanes Mettenius.
Plants small, epiphytic or petrophilous. Rhizome long creeping, or short and erect, slender, filiform. Fronds small to medium-sized. Lamina pinnately decompound, semitransparent, entire or toothed at margin; rachis and/or lamina covered with reddish brown long hairs to glabrescent or glabrous. Involucres bivalvate, deeply cleft nearly halfway to base, or tubular with bivalvate mouth, entire or serrate at apex; receptacles included or projecting. 2n = 22, 26, 36, 42, 44.
About 250 species: throughout the tropics to temperate regions; 22 species (four endemic) in China.
Meringium acanthoides (Bosch) Copeland (Philipp. J. Sci. 67: 42. 1938; Didymoglossum acanthoides Bosch, Pl. Jungh. 1: 560. 1856; Hymenophyllum acanthoides (Bosch) Rosenstock) was an accepted name in FRPS (2: 151. 1959). It was described from Java, Indonesia, and was presumably a misidentification.
The following taxa could not be treated here because no material was seen by the present authors: Hymenophyllum dilatatum (G. Forster) Swartz var. amplum Christ (Bull. Herb. Boissier 7(1): 2-3. 1899), described from Yunnan, and H. henryi Baker (J. Bot. 27: 176. 1889), described from Hubei.
Excluded taxa
Hymenophyllum wrightii Bosch, Ned. Kruidk. Arch. 4: 391. 1859.
莱氏蕗蕨 lai shi lu jue
Mecodium wrightii (Bosch) Copeland.
Plants 1.5-5 cm tall. Rhizome brown or blackish, ca. 0.1 mm in diam., glabrescent. Stipes remote, 1.5-2 cm apart, glabrous, with wings at apex (sometimes decurrent to middle or nearly to base), wings flat. Lamina 2- or 3-pinnatifid, green, ovate-lanceolate, usually 1.5-3.5 × 1-1.5 cm, membranous, glabrous or with a few multicellular hairs, base cordate or sometimes nearly truncate, apex obtuse; free lateral pinnae 2 or 3 pairs, alternate, spreading, ovate or obovate, base cuneate to rounded, apex obtuse or rounded; ultimate segments narrowly elliptic to oblong, 8-10 × 3-4 mm, with 1 veinlet at middle of each segment; segments entire, apex rounded, adnate to costae. Veins dichotomous, obvious; rachis and costae with flat wings throughout. Sori on upper parts of fronds, terminal on segments; involucres 1 per segment, bivalvate, cleft to base, entire, rounded at apex. 2n = 56, 84.
On rocks or tree trunks in wet forests. Taiwan [Japan, Korea, Russia (Siberia); North America (W Canada)].
