38.
Grimmia pulvinata
(Hedwig) Smith in J. E. Smith et al., Engl. Bot. 24: plate 1728. 1807.
Fissidens pulvinatus
Hedwig, Sp. Musc. Frond., 158, plate 40, figs. 1-3. 1801;
Grimmia decipiens
var.
hendersonii
(Renald & Cardot) Sayre;
G. indianensis
(Sayre) H. A. Crum;
G. pulvinata
var.
africana
Hooker f. & Wilson;
G. subcurvula
Kindberg;
G. trichophylla
var
. indianensis
Sayre
Plants
in hemispherical hoary cushions, grayish green.
Stems
1-3 cm, central strand present.
Leaves
flexuose when dry, erect when moist, lanceolate, 1-1.7 × 0.3-0.6 mm, keeled, margin recurved on both sides nearly from base to apex, rarely only one margin recurved, abruptly contracted into short to long, smooth to denticulate awn, costa weak proximally, projecting on abaxial side; basal juxtacostal laminal cells quadrate to short-rectangular, thin-walled; basal marginal laminal cells quadrate to short-rectangular, thin- or thick-walled; medial laminal cells rounded-quadrate, slightly sinuose, thin-walled; distal laminal cells 1-stratose, margins 2-stratose.
Gemmae
absent.
Sexual condition
autoicous.
Seta
arcuate, 3-4 mm.
Capsule
usually present, exserted, ellipsoid to obloid, brownish and ribbed when empty and dry, exothecial cells thin-walled, annulus present, operculum rostrate, peristome teeth reddish, fully-developed, papillose.
Calyptra
mitrate.
Various substrates, from acidic to basic rock, old mortar, tree trunks; low to high elevations (0-3000 m); Alta., B.C., Ont.; Ariz, Calif., Colo., Idaho, Ind., Iowa, Kans., Md., Mich., Miss., Mo., Mont., Nev., N.Mex., Okla., Oreg., S.Dak., Tex., Utah, Wash., Wyo.; Mexico; South America (Argentina, Chile, Uruguay); Eurasia; Africa; Pacific Islands (New Zealand); Australia.
Grimmia pulvinata
is the most common species of the genus. It has a nearly cosmopolitan distribution, and is a pioneer on various substrates, even on the trunks of trees. However, in the eastern part of North America, it occurs only in a few scattered localities (H. A. Crum 1977). It is easily recognized by its neat hemispherical cushions with abundant capsules. It may be confused with
G. orbicularis
, which grows in similar habitats and is known to co-occur with
G. pulvinata.
However, as discussed under G.
orbicularis
, it differs in gametophytic as well as sporophytic characters. Some forms with more acuminate leaf tips may be confused with
G. trichophylla
, but the thin-walled, short-rectangular basal cells and the small, rounded mid leaf cells distinguish
G. pulvinata
.
