Luisierella Moss

Luisierella barbula usually grows in a thin crust associated with cyanobacteria, Hyophiladelphus agrarius, and Weissia jamaicensis, the minute black plants contrasting starkly with the usually chalky white rock surface. The somewhat elevated cells on the adaxial surface of the costa may resemble a differentiated structure (a pad of cells), but the cells appear to be otherwise undifferentiated from those of the lamina.

Plants inconspicuous, nearly stem-less. Stems mostly unbranched, rhizoids or tomentum not evident. Leaves rosulate, 1-1.5(-2) mm, younger leaves nested in a rosette of older leaves, which extends to ¹/2 the length of the younger leaves; distal laminal cells deep green in sharp contrast with colorless proximal cells region, irregularly rounded-hexagonal, 8-11 µm. Sexual condition with bulbous vaginula; antheridia tiny, ¹/3 the length of the archegonia; plants with only perigonia not seen. Capsule 1-2.5 mm; operculum 0.6-1 mm; peristome teeth short, irregular, sometimes appearing absent.

Plants tiny, only to 1.5 mm high, in gregarious tufts. Stems simple, very short, rarely branched. Leaves contorted-curved when dry, erectopatent when moist, lanceo-ligulate, rounded-obtuse at the apex; margins entire, plane or somewhat wavy; costa ending below the apex; upper leaf cells rounded-hexagonal, thick-walled, more or less hyaline, mammillose; basal cells irregularly rectangular, larger than the upper cells, thin-walled, hyaline. Dioicous. Perichaetial leaves not much differentiated from stem leaves. Setae straight, ca. 6 mm long; capsules erect to slightly curved, ovoid-cylindrical; annuli weakly differentiated, of 1 row of cells; opercula conic-rostrate, with a short, thick beak; peristome teeth erect, densely papillose. Spores ca. 7 µm in diameter, smooth.

Distribution: China, Indonesia, Brazil, Honduras, Jamaica, Puerto Rico, Haiti, Cuba, and U.S.A.

Habitat: on rocks or thin soil over rocks, sometimes on tree trunks.

Gymnostomum barbula Schwägrichen, Sp. Musc. Frond. Suppl. 2(2,1): 77, plate 175. 1826

Gyroweisia brevicaulis (C. Müll.) Broth., Nat. Pflanzenfam. I(3): 389. 1902. Didymodon brevicaulis (C. Müll.) Fleisch., Musci Frond. Archip. Ind. Exsic. 6: n. 272. 1902, illeg. hom. Trichostomum brevicaule Hampe ex C. Müll., Syn. Musc. Frond. 1: 567. 1849.