Didymodon nicholsonii

Culmann

Rev. Bryol. 34: 100, figs. 1–9. 1907 (as nicholsoni),.

Synonyms: Didymodon vinealis var. nicholsonii (Culmann) R. H. Zander
Treatment appears in FNA Volume 27. Treatment on page 553. Mentioned on page 542, 554, 560, 561.

Plants green to dark green, usually with a reddish cast. Stems to 2 cm, central strand present. Stem-leaves appressed to weakly spreading when dry, spreading and not keeled when moist, monomorphic, long-ovate or occasionally ovatelanceolate, 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 shortrectangular, 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 shortrectangular, not perforated; distal laminal cells 7–9 µm wide, 1: 1, nearly smooth or papillae simple or 2-fid, 2–3 per lumen, lumens roundedquadrate, 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. Specialized asexual reproduction absent. Seta ca. 1.2 cm. Capsule 1.5–2.1 mm; peristome teeth 32, linear, twisted 1/2 times to once, to 1000 µm. Spores 11–13 µm. Distal laminal KOH reaction light to dark redbrown, occasionally deep red-orange.


Phenology: Capsules mature spring–summer.
Habitat: Wet rocks, quartzite, wet silty sand, stream bank, canyon walls, streamside, chaparral
Elevation: low to high elevations (50-1900 m)

Distribution

V27 794-distribution-map.gif

B.C., Calif., Mont., Nev., Oreg., Utah, Europe, Asia (Afghanistan)

Discussion

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.

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 nicholsonii"
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 +
not fragile +
Acute (?) +  and Blunt (?) +
Richard H. Zander +
Culmann +
weak +  and strong +
ovate +  and crescent--shaped +
papillose +  and smooth +
usually slightly wider +
oblong;ovate +
differentiated +
Pottiaceae tribe Barbuleae +
obovoid +
cucullate +
stegocarpous +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.21 cm2.1 mm <br />0.0021 m <br />) +
monoicous +, dioicous +  and sexual +
flat to bulging +
thin;thick +
entire +, 2-stratose +  and 1-stratose +
1 (?) +  and 10 (?) +
hexagonal +
tomentose +  and bare +
ending before the apex +  and percurrent +
tapering +
widened +
quadrate +  and rectangular +
occasionally weakly dentate or crenulate +  and entire +
subquadrate;hexagonal or rounded-angular occasionally shortly rectangular or rhomboid +
B.C. +, Calif. +, Mont. +, Nev. +, Oreg. +, Utah +, Europe +  and Asia (Afghanistan) +
low to high elevations (50-1900 m) +
differentiated +
multicellular +
occasional +
Wet rocks, quartzite, wet silty sand, stream bank, canyon walls, streamside, chaparral +
yellow +  and orange-red or red +
grooved +  and monomorphic +
0 cm0 mm <br />0 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
spreading +, appressed +  and weakly spreading +
lanceolate;ovatelanceolate;long-ovate;keeled +
specialized +
ovate +, keeled +  and curled +
reduced +
specialized +
dioicous +  and sexual +
roundedquadrate +
short-conic;long-conic +
photosynthetic +
2 +  and 3 +
lateral +  and terminal +
lateral +  and terminal +
red-orange +, light +  and dark redbrown +
oblong +  and linear or long-triangular +
1/2 times to 0-1000 um . spores +
Capsules mature spring–summer. +
1 (?) +  and 2 (?) +
Rev. Bryol. +
straight +
yellowish;reddish-brown +
elongate +
1.2 cm12 mm <br />0.012 m <br /> (?) +
2 +  and 1 +
yellow +, red-orange +, red +  and laminal +
rounded-triangular +  and rounded-pentagonal +
0 cm0 mm <br />0 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Didymodon vinealis var. nicholsonii +
Didymodon nicholsonii +
Didymodon +
species +
elliptic;cylindric +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
rudimentary +
2-stratose +  and not perforated +
red +  and yellow +
convex +  and quadrate +
thin +  and weakly thickened +
stemless +  and perigoniate +