Didymodon rigidulus var. gracilis

(Schleicher ex Hooker & Greville) R. H. Zander

Cryptog. Bryol. Lichénol. 2: 393. 1981,.

Basionym: Tortula gracilis (Bridel) Bridel Edinburgh J. Sci. 1: 300. 1824
Synonyms: Barbula acuta (Bridel) K. Saito Didymodon acutus
Treatment appears in FNA Volume 27. Treatment on page 545. Mentioned on page 543, 544.

Stem-leaves appressed to weakly spreading when dry, costa usually percurrent to short-excurrent as a rigid subula, short-lanceolate, seldom-lanceolate, base evenly broadened, ovate to elliptic or oblong, proximal cells shortrectangular, distal laminal cells usually papillose, quadrate, with quadrate lumens, occasionally 2-stratose on the margins in patches; gemmae often present in distal leaf-axils. Peristome teeth short and straight to long and twisted.


Phenology: Capsules mature spring–winter.
Habitat: Basalt, calcareous outcrops and ledges, gravel, soil, silt, frostboil, tundra, along roads and paths
Elevation: low to high elevations (0-3000 m)

Distribution

V27 779-distribution-map.gif

Greenland, Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Sask., Yukon, Alaska, Ariz., Colo., Iowa, Kans., Minn., Mo., Mont., Nev., N.Mex., S.Dak., Tenn., Tex., Utah, Wis., Wyo., Mexico, Central America, South America, Europe, Asia (Siberia), Africa, Atlantic Islands (Iceland)

Discussion

Variety gracilis may sometimes have gemmae and the distal lamina is occasionally 2-stratose in patches, but it differs from var. rigidulus most clearly in its the short- to long-lanceolate leaves. The distal laminal cells are commonly papillose, and their lumens are oval or rounded-quadrate. Because of intergradation, some collections must be assigned to this variety only on the basis of a majority of the characters given in the key. Although leaves in this variety are short in dry habitats, associated with fragile stems, leaf length in collections from moist environments is generally longer. The small distal laminal cells, broad costa to 6 cells in width at mid leaf, and the strong stem central strand serve to distinguish this taxon from Didymodon asperifolius.

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.

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 +
Acute (?) +  and Subulate (?) +
Richard H. Zander +
(Schleicher ex Hooker & Greville) R. H. Zander +
weak +  and strong +
ovate +  and crescent--shaped +
papillose +  and smooth +
usually slightly wider +
ovate;elliptic or oblong +
differentiated +
broadened +
Tortula gracilis +
obovoid +
cucullate +
stegocarpous +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
monoicous +, dioicous +  and sexual +
flat to bulging +
thin;thick +
1 (?) +  and 10 (?) +
hexagonal +
differentiated +
tomentose +  and bare +
usually percurrent +  and short-excurrent +
seldom-lanceolate +  and short-lanceolate +
widened +
quadrate +  and rectangular +
occasionally weakly dentate or crenulate +  and entire +
subquadrate;hexagonal or rounded-angular occasionally shortly rectangular or rhomboid +
Greenland +, Alta. +, B.C. +, Man. +, Nfld. and Labr. +, N.W.T. +, Nunavut +, Ont. +, Que. +, Sask. +, Yukon +, Alaska +, Ariz. +, Colo. +, Iowa +, Kans. +, Minn. +, Mo. +, Mont. +, Nev. +, N.Mex. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Wis. +, Wyo. +, Mexico +, Central America +, South America +, Europe +, Asia (Siberia) +, Africa +  and Atlantic Islands (Iceland) +
low to high elevations (0-3000 m) +
differentiated +
multicellular +
occasional +
Ovate (?) +  and Elliptic (?) +
Basalt, calcareous outcrops and ledges, gravel, soil, silt, frostboil, tundra, along roads and paths +
yellow +  and orange-red or red +
long-ligulate +  and monomorphic +
0.17 cm1.7 mm <br />0.0017 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
not +, spreading +, appressed-incurved +  and weakly spreading +
channeled;ovatelanceolate;keeled +
ovate +, keeled +  and curled +
reduced +
specialized +
dioicous +  and sexual +
quadrate +
short-conic;long-conic +
photosynthetic +
lateral +  and terminal +
lateral +  and terminal +
red-orange +  and yellow +
0-740 um +  and rudimentary +
0-740 um +  and occasionally absent +
0-740 um-triangular +  and long-triangular +
Capsules mature spring–winter. +
1 (?) +  and 2 (?) +
Cryptog. Bryol. Lichénol. +
straight +
yellowish;reddish-brown +
elongate +
0.7 cm7 mm <br />0.007 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
2 +  and 1 +
yellow +, red-orange +, red +  and laminal +
appressed;weakly spreading +
rounded-triangular +  and rounded-pentagonal +
0 cm0 mm <br />0 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Barbula acuta +  and Didymodon acutus +
Didymodon rigidulus var. gracilis +
Didymodon rigidulus +
variety +
elliptic;cylindric +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
rudimentary +
red +  and yellow +
specialized +
thin +  and evenly thickened +
stemless +  and perigoniate +