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revolute didymodon moss

Habit Plants usually blackish green. Plants usually green to blackish green.
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, imbricated, incurved when dry, widely spreading and not keeled when moist, monomorphic, ovate to elliptical, broadly concave adaxially across leaf, usually 0.4–1(–2) mm, base scarcely differentiated in shape, margins usually recurved to revolute to near apex but sometimes plane, entire, apex obtuse to rounded, often strongly cucullate, not fragile;

costa percurrent or ending a 2–6 cells below the apex, slightly broader at mid leaf, usually strongly spurred, little tapering, with a low adaxial pad of cells, adaxial costal cells quadrate, (4–)6–8 cells wide at mid leaf, guide cells in 1 layer;

basal laminal cells differentiated somewhat medially or across leaf, walls weakly thickened or thin, rectangular, not perforated;

distal laminal cells 7–10 wide, 1:1, papillae absent or low, simple or 1 multiplex, rather flat papilla per lumen, lumens oval to rounded-quadrate, walls convex on both sides of lamina, 1-stratose or occasionally 2-stratose in patches.

Seta

0.7–1 cm.

0.4–0.9 cm.

Capsule

1–1.9 mm;

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

0.7–1.5 mm;

peristome teeth absent to rudimentary, irregularly ligulate, to 65 µm.

Spores

11–15 µm.

9–11 µm.

Specialized

asexual reproduction by multicellular tubers on proximal rhizoids.

asexual reproduction rare, by unicellular gemmae in masses in leaf axils.

Distal

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

laminal KOH reaction light brown to medium orange-brown.

Didymodon australasiae

Didymodon revolutus

Phenology Capsules mature winter–spring. Capsule maturity not determined.
Habitat Soil, gypsum, acid rock, ledges, sandstone, silt Seep, sandstone outcrop, cliffs, associated with prairie grasses
Elevation moderate to high elevations (300-2000 m) (moderate to high elevations (1000-6600 ft)) low to moderate elevations (100-1500 m) (low to moderate elevations (300-4900 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
AZ; CA; MO; NM; OK; TX; Mexico; Central America; South America; Asia (Yemen)
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.)

Distinctive characters of Didymodon revolutus in combination are: arid habitat, ovate leaves with often revolute margins, subpercurrent, strongly spurred costa (with one or more lateral costal cells wending into the lamina), one layer of guide cells, and rudimentary or absent peristome. Like Didymodon perobtusus and Bryoerythrophyllum calcareum, D. revolutus has unicellular gemmae occasionally present in the leaf axils; the similar D. brachyphyllus has multicellular gemmae, has ovate to short-lanceolate leaves that lack hydroids in the costa, and have laminal cell lumens that are quadrate or angled. In an Arizona collection (E. B. Bartram 1688, Musci Acroc. Bor.-Amer. Eur. 642, NY), D. brachyphyllus and D. revolutus were mixed, though easily separated by the above characters.

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

Source FNA vol. 27, p. 547. FNA vol. 27, p. 548.
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. nicholsonii, D. nigrescens, D. norrisii, D. perobtusus, 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 Husnotiella revoluta, Husnotiella revoluta var. palmeri
Name authority (Hooker & Greville) R. H. Zander: Phytologia 41: 21. (1978) (Cardot) R. S. Williams: Bryologist 16: 25. (1922)
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