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giant beard moss

Habit Plants usually blackish green. Plants red-brown.
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 when dry, spreading or weakly recurved and keeled when moist, monomorphic, elliptic-lanceolate, adaxially grooved along costa, (2–)2.5–4 mm, base scarcely differentiated in shape to elliptic, margins nearly broadly recurved in proximal 1/3–3/4 of leaf, entire, apex acute or gradually acuminate, not fragile;

costa percurrent, tapering and distinctly widened at base, widened pad of cells absent, adaxial costal cells elongate, 5–7 cells wide at mid leaf, guide cells in 1 layer;

basal laminal cells differentiated medially, rectangular, walls thickened and porose;

distal laminal cells 13–15 µm wide, 1:1 or occasionally transversely elongated, papillae absent or simple, low, present only on the back of the leaf near the apex, lumens angular, walls irregularly thickened and trigonous with trigones about the same size as the lumens, weakly convex on both sides, 1-stratose.

Seta

0.7–1 cm.

Sexual condition

sterile.

Capsule

1–1.9 mm;

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

Spores

11–15 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 dark red.

Sporophytes

not seen.

Didymodon australasiae

Didymodon giganteus

Phenology Capsules mature winter–spring.
Habitat Soil, gypsum, acid rock, ledges, sandstone, silt Soil, cliff, slopes, lichen tundra, ledges, moist areas
Elevation moderate to high elevations (300-2000 m) (moderate to high elevations (1000-6600 ft)) low to moderate elevations (20-1000 m) (low to moderate elevations (100-3300 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; BC; NT; 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 giganteus commonly forms large tufts on slopes and ledges in the far North. Several specimens, collected in Alaska, have been seen with the above combination of characters, which is that of European specimens. Many collections, however, that had been previously identified as this species but having weak trigones are either D. ferrugineus or D. maximus.

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

Source FNA vol. 27, p. 547. FNA vol. 27, p. 559.
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. 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 gigantea, Geheebia gigantea
Name authority (Hooker & Greville) R. H. Zander: Phytologia 41: 21. (1978) (Funck) Juratzka: Laubm. Fl. Oesterr.-Ung., 102. (1882)
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