Didymodon nigrescens

(Mitten) K. Saito

J. Hattori Bot. Lab. 39: 510. 1975,.

Basionym: Barbula nigrescens Mitten J. Proc. Linn. Soc., Bot., suppl. 1: 36. 1859
Synonyms: Barbula rufofusca E. Lawton & F. J. Hermann
Treatment appears in FNA Volume 27. Treatment on page 549. Mentioned on page 110, 541, 546, 558, 581.

Plants usually red to black-brown, occasionally yellow or orangebrown at apex. Stems 1.5–2.3 cm, central strand absent or present. Stem-leaves appressed when dry, spreading and not keeled when moist, monomorphic, long-ovate to lanceolate, broadly concave adaxially across leaf, usually 0.8–1.7 mm, base weakly differentiated in shape, long-ovate, margins usually broadly recurved to revolute to mid leaf or to near apex, minutely crenulate, apex acute to narrowly acuminate, often weakly cucullate; costa percurrent or ending 2–4 cells below the apex, little tapering, not strongly spurred, without an adaxial pad of cells, adaxial costal cells rectangular, 2 cells wide at mid leaf grading to 4 below, guide cells in 1 layer; basal laminal cells differentiated medially, walls thick, rectangular, not perforated; distal laminal cells in rows, 7–11 (–14) µm wide, 1: 1 or often longitudinally elongate, papillae apparently absent but visible in section as low, flattened to multiplex capitulate lenses, 1–3 per lumen, lumens ovate, walls evenly thickened and weakly convex on both sides of lamina, 1-stratose. Specialized asexual reproduction absent. Seta 0.7–0.9 cm. Capsule 1.5–2.8 mm; peristome teeth 32, linear, straight to twisted 1.5 times, 100–600 µm. Spores 9–13 µm. Distal laminal KOH reaction red.


Phenology: Capsules mature spring–fall.
Habitat: Limestone, frostboils, outcrops, cliff faces, often near streams and waterfalls
Elevation: low to moderate elevations (0-700 m)

Distribution

V27 787-distribution-map.gif

B.C., N.W.T., Alaska, Central America (Guatemala), e Asia

Discussion

The specimens cited as Didymodon nigrescens from the Firth River Basin by W. C. Steere (1978), determined by R. H. Zander, are actually Didymodon subandreaeoides. The distinguishing characters of D. nigrescens are the blackish coloration when dry (red in KOH), thin costa and distal laminal margins minutely crenulate by the small, bulging marginal cells. This and the following two species appear to be closely related by the rather distinctive crenulation of the leaf apices. Didymodon asperifolius is similar but may be distinguished by its longer leaves, straight or reflexed to strongly recurved when wet, distal margins recurved and smooth, distal laminal cells larger, 10–13 µm wide, epapillose or papillae simple, costa usually rather wide.

Selected References

None.

Lower Taxa

None.

"um" is not declared as a valid unit of measurement for this property."um" is not declared as a valid unit of measurement for this property.

... more about "Didymodon nigrescens"
quadrate +  and elongate +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
channeled +, concave +  and long-triangular +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
of 1-2 rows +  and differentiated +
long-excurrent +  and short-excurrent +
Richard H. Zander +
(Mitten) K. Saito +
weak +  and strong +
ovate +  and crescent--shaped +
papillose +  and smooth +
usually slightly wider +
long-ovate;differentiated +
differentiated +
Barbula nigrescens +
obovoid +
cucullate +
stegocarpous +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.28 cm2.8 mm <br />0.0028 m <br />) +
monoicous +, dioicous +  and sexual +
flat to bulging +
thin;thick +
1 (?) +  and 10 (?) +
hexagonal +
tomentose +  and bare +
ending 2-4 cells +  and percurrent +
tapering +
quadrate +  and rectangular +
occasionally weakly dentate or crenulate +  and entire +
subquadrate;hexagonal or rounded-angular occasionally shortly rectangular or rhomboid +
B.C. +, N.W.T. +, Alaska +, Central America (Guatemala) +  and e Asia +
low to moderate elevations (0-700 m) +
differentiated +
multicellular +
occasional +
Limestone, frostboils, outcrops, cliff faces, often near streams and waterfalls +
yellow +  and orange-red or red +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
concave;long-ovate;lanceolate +
ovate +, keeled +  and curled +
reduced +
specialized +
dioicous +  and sexual +
dentate +  and entire +
short-conic;long-conic +
photosynthetic +
solid +  and simple +
1 +  and 3 +
flattened +
lateral +  and terminal +
lateral +  and terminal +
oblong +  and linear or long-triangular +
1.5 times 100-600 um . spores +
Capsules mature spring–fall. +
1 (?) +  and 2 (?) +
J. Hattori Bot. Lab. +
straight +
7um;11um +
yellowish;reddish-brown +
elongate +
0.7 cm7 mm <br />0.007 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
2 +  and 1 +
yellow +, red-orange +, red +  and laminal +
rounded-triangular +  and rounded-pentagonal +
1.5 cm15 mm <br />0.015 m <br /> (2.3 cm23 mm <br />0.023 m <br />) +
Barbula rufofusca +
Didymodon nigrescens +
Didymodon +
species +
elliptic;cylindric +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
rudimentary +
1-stratose +  and not perforated +
red +  and yellow +
specialized +
convex +  and rectangular +
stemless +  and perigoniate +
usually red;black-brown occasionally yellow or orangebrown +