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nicholson's beard moss

Habit Plants usually blackish green. Plants green to dark green, usually with a reddish cast.
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 to weakly spreading when dry, spreading and not keeled when moist, monomorphic, long-ovate or occasionally ovate-lanceolate, rarely lanceolate, grooved adaxially along the costa, especially near leaf apex, to 3.5 mm, base scarcely differentiated to ovate or oblong in shape, margins narrowly recurved in proximal 3/4 of leaf, entire, apex acute to blunt, not fragile;

costa percurrent or ending before the apex, not strongly spurred, not much widened or tapering, lacking an adaxial pad of cells, adaxial costal cells quadrate to short-rectangular, ca. 6 cells wide at mid leaf, guide cells in 1(–2) layers;

basal laminal cells very weakly differentiated medially, walls thin to weakly thickened, quadrate to short-rectangular, not perforated;

distal laminal cells 7–9 µm wide, 1:1, nearly smooth or papillae simple or 2-fid, 2–3 per lumen, lumens rounded-quadrate, walls thickened, weakly convex on both sides of lamina, 2-stratose in distal leaf half or occasionally only in patches or very rarely 1-stratose, cells of distal leaf margins 2-stratose or occasionally entire leaf 2-stratose distally.

Seta

0.7–1 cm.

ca. 1.2 cm.

Capsule

1–1.9 mm;

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

1.5–2.1 mm;

peristome teeth 32, linear, twisted 1/2 times to once, to 1000 µm.

Spores

11–15 µm.

11–13 µm.

Specialized

asexual reproduction by multicellular tubers on proximal rhizoids.

asexual reproduction absent.

Distal

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

laminal KOH reaction light to dark red-brown, occasionally deep red-orange.

Didymodon australasiae

Didymodon nicholsonii

Phenology Capsules mature winter–spring. Capsules mature spring–summer.
Habitat Soil, gypsum, acid rock, ledges, sandstone, silt Wet rocks, quartzite, wet silty sand, stream bank, canyon walls, streamside, chaparral
Elevation moderate to high elevations (300-2000 m) (moderate to high elevations (1000-6600 ft)) low to high elevations (50-1900 m) (low to high elevations (200-6200 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
CA; MT; NV; OR; UT; BC; Europe; Asia (Afghanistan)
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 nicholsonii intergrades somewhat with D. vinealis but the ovate-lanceolate leaves are distinctive as is the tendency to a partially or completely 2-stratose distal lamina. It may be confused with D. rigidulus but has a broader leaf apex, the costa commonly ending before the apex, a deep apical groove over the costa, and 2-stratose distal marginal cells often in a narrow band. The western species Grimmia cinclidontea Müller Hal. is similar and grows in similar habitats, but is autoicous, has smooth leaf cells and a homogeneous costal section. S. Flowers’s (1973) illustration of D. rigidulus is actually of D. nicholsonii.

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

Source FNA vol. 27, p. 547. FNA vol. 27, p. 553.
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. asperifolius, 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. 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 D. vinealis var. nicholsonii
Name authority (Hooker & Greville) R. H. Zander: Phytologia 41: 21. (1978) Culmann: Rev. Bryol. 34: 100, figs. 1–9. 1907 (as nicholsoni),
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