Didymodon vinealis
Didymodon nevadensis
didymodon moss, soft-tuft beard-moss
gold butte beard moss
leaves often twisted, appressed to weakly spreading or spreading-flexuose when dry, spreading to spreading-recurved and not keeled when moist, monomorphic, lanceolate, grooved adaxially along the costa, especially near leaf apex, 0.8–2.5(–4) mm, base scarcely differentiated to oblong in shape, margins recurved below mid leaf or to above mid leaf, entire, apex acute, not fragile, commonly ending in a conical cell;
costa percurrent or more commonly short-excurrent, not strongly spurred, not much widened or tapering, lacking an adaxial pad of cells, adaxial costal cells quadrate to short-rectangular, ca. 4 cells wide at mid leaf, guide cells in 1(–2) layers;
basal laminal cells differentiated medially or across the leaf, walls thin to weakly thickened, rectangular or seldom quadrate, not perforated;
distal laminal cells 7–10 µm wide, 1:1, nearly smooth or papillae simple or 2-fid, 2–3 per lumen, lumens irregular or oval to rounded-quadrate, walls thin or evenly thickened, convex on both sides of lamina, 1-stratose or occasionally 2-stratose in patches.
leaves spirally twisted and appressed to weakly spreading when dry, weakly spreading and not keeled when moist, monomorphic, ovate to ovate-lanceolate, grooved adaxially along the costa, especially near leaf apex, to 0.6–1 mm, base ovate in shape, margins broadly recurved to revolute to apex of leaf, entire, apex conic-acute to obtuse, not fragile, commonly ending in a conical cell;
costa percurrent, not strongly spurred, widened medially, with a broad adaxial 1-stratose pad of thin-walled cells, adaxial costal cells quadrate to short-rectangular, 7–9 cells wide at mid leaf, guide cells in 2(–3) layers;
basal laminal cells differentiated medially or across the leaf, walls thin to evenly thickened, short-rectangular, not perforated;
distal laminal cells 8–10 µm wide, 1:1 or occasionally 1:2, nearly smooth or papillae often as a thickened and irregularly shaped lens covering the lumen, lumens quadrate, walls thin or weakly thickened, weakly convex on both sides of lamina, distal leaf margins 1-stratose.
0.8–1 cm.
only perichaetiate plants seen.
1.5–2.5 mm;
peristome teeth 32, linear, twisted 1/2 to once, to 1300 µm, occasionally rudimentary or absent.
9–12 µm. Distal laminal KOH reaction light to dark red-brown, occasionally deep red-orange.
asexual reproduction very rare, by multicellular gemmae in clusters in leaf axils.
asexual reproduction by rhizoidal tubers or axillary gemmae of (2–)4–6(–10) cells.
unknown.
laminal KOH reaction blotchy or irregularly blushing red at mid leaf or above, otherwise colorless or light yellow.
Didymodon vinealis
Didymodon nevadensis
Varieties 2 (2 in the flora).
Didymodon vinealis is often difficult to distinguish from sterile forms of D. rigidulus, but the elongate cells commonly found on the adaxial surface of the costa near the boat-shaped leaf apex, the often strongly papillose laminal cells, and the usual presence of a distinct groove down the adaxial surface of the leaf along the costa are characteristic features. Some but not all specimens may be quickly assigned to this taxon by a unique deep slit floored by elongate cells on the adaxial surface of the costal apex (the adaxial epidermis being absent), visible as a clear window abaxially. Bryoerythrophyllum recurvirostrum is immediately distinguished by the clear, enlarged proximal cells. Like Bellibarbula recurva, small forms of D. vinealis may have quadrate or very short-rectangular proximal cells and sinuose costa, but the former has thick-walled proximal cells and the costa twists laterally, not vertically in the concave distal portion of the leaf of D. vinealis, and the adaxial cells of the costa of commonly elongate, 2:1 or more.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Didymodon nevadensis is similar to Pseudocrossidium crinitum and has much the same appearance under the dissecting microscope. It differs by the somewhat cucullate, acute leaf apex, the costa percurrent (not excurrent as a short awn, smaller distal laminal cells (13–15 µm for P. crinitum), and occasional presence of tubers on the proximal rhizoids. Like P. crinitum, D. nevadensis has blotches of red coloration at mid leaf and above, and this irregular red coloration distinguishes it from Bryoerythrophyllum species, which are evenly colored red. This species has two layers of guide cells (occasionally to three near the leaf base), while P. crinitum is nearly constant in a single layer of guide cells. Unlike B. columbianum, which has somewhat the same apearance and rather broad distal costa, the leaf apices of D. nevadensis are not fragile and specialized asexual reproduction is by several-celled spheric propagula born on rhizoids in the proximal leaf axils, as well as occasionally by brood bodies on the rhizoids. This species differs further from B. columbianum by the blunt, rather cucullate leaf apices comprised of nearly isodiametric cells, and leaf margins more loosely recurved to revolute. Didymodon australasiae is similar to D. nevadensis but its leaves differ in the thin-walled proximal cells and 2-stratose distal margins; small plants of D. australasiae are quite similar to D. nevadensis, especially in the appearance of the leaf apex, the rather broad and adaxially protuberant costa, the double layer of guide cells and lack of an adaxial stereid band, and the few-celled propagula borne on proximal rhizoids, but the former has 2-stratose cells in the leaf apices. Didymodon nevadensis differs from the very similar Tortula atrovirens in its ovate leaf shape, deep groove at the leaf apex, smaller leaf cells, and very weak, flattened abaxial stereid band, the latter having a short oblong leaf shape, broadly channeled leaf apex, large leaf cells (to 18 µm wide) and strong, rounded stereid band; S. Flowers (1973, plate 31) treated and illustrated both species under the name Desmatodon convolutus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Peristome present, well developed, cells of operculum twisted | var. vinealis |
1. Peristome absent, cells of operculum straight or nearly so | var. rubiginosus |
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