Hyophila involuta Jaeger 1873

Cells covering the adaxial costal surface in the related genus Plaubelia are rounded and similar to the laminal cells, being small and generally isodiametric; those of Hyophila are rather different from the laminal cells, being somewhat larger and quadrate to short-rectangular. The adaxial costal cells of Plaubelia are more saliently mammillose than those of Hyophila, but this is not always easy to establish. In the flora the range of Plaubelia is restricted to Florida, whereas that of Hyophila involuta extends from Florida north to Ontario. For distinction of Hyophila from Dichodontium pellucidum, see discussion of the latter species. Hyophila involuta apparently rarely fruits in the flora area (one old sporophyte was seen from Ohio; one fruiting specimen from New Jersey was noted by A. J. Grout 1928-1940).

Plants small, to 14 mm high, yellowish green, in dense tufts. Stems erect, simple or branched; central strand absent. Leaves involute to subtubulose when dry, erect- to wide-spreading when moist, oblong-ovate to oblong-spatulate, 1.7–3.0 mm × 0.6–0.8 mm, broadly acute to obtusely apiculate, slightly reflexed at the base; margins serrate in the upper half; costa stout, percurrent to shortly excurrent; upper leaf cells small, subquadrate to rounded hexagonal, 5–8 µm × 5–7 µm, somewhat thick-walled, not papillose, slightly mammillose on the ventral surface; basal cells short-rectangular, 28–62 µm × 10–18 µm, pale or hyaline. Gemmae present. Dioicous. Setae ca. 10–15 mm long, yellowish green to reddish brown, not twisted; capsules erect, cylindrical; opercula conic-rostrate with a long beak; annuli present. Spores 9–11 µm in diameter, nearly smooth.

Plants in loose or dense, dark green to red-brown or blackish tufts, dull or occasionally with a metallic sheen. Stem densely foliate, 5-10(-20) mm, central strand strong. Leaves concave when moist, to 1.5-2(-2.5) mm, oblong-spatulate to obovate, occasionally with multicellular teeth in distal ¹/4, rounded to rounded obtuse at the apex, sometimes apiculate; costa stout, prominent abaxially, smooth on the abaxial surface to occasionally roughened at the apex, hydroids absent; laminal cells near insertion short-rectangular, 2-4:1, firm-walled, pale and brownish or hyaline, cells 8-10(-12) µm wide, in longitudinal and oblique rows, thin to thick-walled, bulging-mammillose on the adaxial surface, plane on the abaxial. Sexual condition dioicous. Seta 6-7 mm, reddish to yellow-brown with age. Capsule erect, 1.5-3 mm, narrowly cylindric from an indistinct neck, annulus well differentiated, red-brown, of vesiculose cells, persistent or deciduous; [operculum erect, conic-rostrate, 0.6-0.8 mm].

Distribution: China, Japan, Nepal, India, Myanmar, Vietnam, Indonesia, Russia, Europe, South and North America, and Oceania.

Habitat: on calcareous rocks, soil, or grasslands.

Hyophila attenuata Broth., Symb. Sin. 4: 37. 1929. Type. China: Yunnan, Nujiang (Lu-jiang) valley, Handel-Mazzetti 9839 (holotype H). Hyophila micholitzii Broth., Öfvers. Forh. Finska Vetensk.-Soc. 35: 39. 1893. Hyophila moutieri Par. & Broth. in Paris, Rev. Bryol. 28: 38. 1901. Type. China: Hainan, 30 VIII 1900, Moutier s.n. Hyophila sinensis Dix., Sci. Rep. Natl. Tsing Hua Univ., ser. B, Biol. Sci. 2: 117. 1936, nom. nud. Hyophila tortula (Schwaegr.) Hampe, Bot. Zeitung (Berlin) 4: 267. 1846.

Gymnostomum involutum Hooker, Musci Exot. 2: plate 154. 1819; Hyophila tortula (Schwägrichen) Hampe