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didymodon moss, rough-leaf beard-moss, rough-leaf green-beard moss

Habit Plants usually blackish green. Plants orange-green or red-brown, occasionally blackish.
Stem(s)

leaves spreading-incurved and twisted to incurved-appressed when dry, spreading to spreading-recurved and not keeled when moist, monomorphic, short-lanceolate or sometimes short-ovate to long-elliptic, broadly concave adaxially across leaf, usually 1–2.5 mm, base scarcely differentiated in shape to ovate, margins usually recurved at mid leaf, entire, apex broadly acute or occasionally narrowly so, not fragile;

costa percurrent or ending a few cells below the apex, broader at mid leaf, occasionally weakly spurred, with a low adaxial pad of cells, adaxial costal cells quadrate, 4–6 cells wide at mid leaf, guide cells in 1–2 layers;

basal laminal cells differentiated medially or across leaf, quadrate to short-rectangular, walls very thin and not perforated;

distal laminal cells 7–12 wide, 1:1 or occasionally transversely elongate below, papillae usually distinct, low or simple to 2-fid, occasionally absent, lumens oval to rounded-quadrate, walls thin to evenly thickened, convex on both sides of lamina, 2-stratose in one or more rows along margins.

leaves appressed-incurved when dry, usually strongly recurved and keeled when moist, monomorphic, triangular to lanceolate, adaxially grooved along costa, 1.2–2.5 mm, base ovate, margins strongly and broadly recurved in proximal 1/2 or up to near apex, entire, apex narrowly to broadly acute, not fragile, commonly ending in a conical cell;

costa percurrent or ending 1–4 cells before the apex, tapering, widened pad of cells absent, adaxial costal cells quadrate to short-rectangular, 4–6 cells wide at mid leaf, guide cells in 1 layer;

basal laminal cells differentiated medially or across leaf, rectangular, walls usually thickened;

distal laminal cells 13–15 µm wide, 1:1, papillae usually absent, rarely simple, weak and domelike, 1 per lumen, lumens rounded or angular, walls thickened, often irregular or very weakly trigonous, weakly to strongly convex on both sides, 1-stratose.

Seta

0.7–1 cm.

0.4–0.6 cm.

Capsule

1–1.9 mm;

peristome teeth 32, linear, weakly twisted, to 600 µm, occasionally rudimentary.

ca. 1 mm;

peristome teeth 16, short-lanceolate to linear, irregularly cleft or perforate to near base, straight, to 50–300 µm.

Spores

11–15 µm.

13–15 µm.

Specialized

asexual reproduction by multicellular tubers on proximal rhizoids.

asexual reproduction specialized structures absent.

Distal

laminal KOH reaction variously negative or yellow- or orange- or red-brown.

laminal KOH reaction red.

Didymodon australasiae

Didymodon asperifolius

Phenology Capsules mature winter–spring. Capsule maturity undetermined.
Habitat Soil, gypsum, acid rock, ledges, sandstone, silt Calcareous or acid rock, moist calcareous soil, peatland, streamside, alpine
Elevation moderate to high elevations (300-2000 m) (moderate to high elevations (1000-6600 ft)) moderate to high elevations (500-3700 m) (moderate to high elevations (1600-12100 ft))
Distribution
from FNA
AZ; CA; CO; NM; NV; OR; TX; Mexico; Central America; South America; Europe; n Africa; s Africa; Pacific Islands (New Zealand); Australia
from FNA
AK; CO; AB; BC; LB; NT; NU; YT; Greenland; Europe; Asia
Discussion

In North American Didymodon, hydroids are found in the costae of D. anserinocapitatus, D. australasiae, D. nevadensis, D. norrisii, D. umbrosus, D. revolutus, and D. vinealis, and in these species the adaxial stereid band is usually absent in well developed specimens. Intergrades exist between D. australasiae and D. umbrosus, but the extreme forms are common and quite distinctive.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Didymodon asperifolius can sometimes be immediately recognized by a red-yellow translucency in leaves of dry plants, like oiled paper. The adaxial surface of the costa may have either quadrate or short-rectangular cells. The distal laminal cells are also rather large for the genus. The KOH reaction, as well as the natural color of the lamina are sometimes light orange, but usually quite red. Some plants may appear green but the laminal cell walls are red under high magnification.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 27, p. 547. FNA vol. 27, p. 560.
Parent taxa Pottiaceae > subfam. Barbuloideae > Didymodon Pottiaceae > subfam. Barbuloideae > Didymodon
Sibling taxa
D. anserinocapitatus, D. asperifolius, D. bistratosus, D. brachyphyllus, D. eckeliae, D. fallax, D. ferrugineus, D. giganteus, D. johansenii, D. leskeoides, D. maschalogena, D. maximus, D. murrayae, D. nevadensis, D. nicholsonii, D. nigrescens, D. norrisii, D. perobtusus, D. revolutus, D. rigidulus, D. subandreaeoides, D. tectorum, D. tophaceus, D. umbrosus, D. vinealis
D. anserinocapitatus, D. australasiae, D. bistratosus, D. brachyphyllus, D. eckeliae, D. fallax, D. ferrugineus, D. giganteus, D. johansenii, D. leskeoides, D. maschalogena, D. maximus, D. murrayae, D. nevadensis, D. nicholsonii, D. nigrescens, D. norrisii, D. perobtusus, D. revolutus, D. rigidulus, D. subandreaeoides, D. tectorum, D. tophaceus, D. umbrosus, D. vinealis
Synonyms Tortula australasiae, D. diaphanobasis, Husnotiella torquescens, Trichostomopsis australasiae, Trichostomopsis brevifolia, Trichostomopsis diaphanobasis, Trichostomopsis fayae Barbula asperifolia, D. rufus
Name authority (Hooker & Greville) R. H. Zander: Phytologia 41: 21. (1978) (Mitten) H. A. Crum: Bryologist 67: 163. (1964)
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