Brachythecium laetum

(Bridel) Schimper in P. Bruch and W. P. Schimper

in P. Bruch and W. P. Schimper, Bryol. Europ. 6: 24. 1853.

Basionym: Hypnum laetum Bridel Bryol. Univ. 2: 479. 1827
Synonyms: Brachythecium digastrum Müller Hal. ex Kindberg
Treatment appears in FNA Volume 28. Treatment on page 422. Mentioned on page 406, 415, 421, 426, 441, 443.

Plants medium-sized, in moderately loose to dense mats, light green, sordid green, or yellowish to brownish. Stems to 7 (–12) cm, creeping, terete-foliate, irregularly pinnate, branches to 12 (–25) mm, straight to slightly curved, terete-foliate. Stem-leaves erect, loosely to densely imbricate, narrowly ovate-triangular, broadest at 1/12–1/8 leaf length, partially concave, deeply plicate, (1–) 1.3–2.2 × (0.4–) 0.6–1 mm; base rounded, decurrent; margins plane or recurved at places, serrulate almost to base; apex gradually acuminate; costa to 55–75% leaf length, moderately weak, terminal spine absent; alar cells subquadrate, same size as or smaller than basal-cells, (8–) 10–13 × 10–15 µm, walls thin, region not clearly differentiated, to 8–15 cells along margins; laminal cells elongate, 25–70 × 5–8 µm; basal-cells small, 15–25 × (6–) 8–11 µm, region in 3 rows near costa, opaque, markedly different from more distal cells. Branch leaves less plicate; costal terminal spine sometimes present. Sexual condition dioicous. Seta brownish orange, 0.7–2.5 cm, smooth. Capsule slightly inclined, brownish orange, cylindric, slightly curved distally, 2–2.6 mm; annulus not separating; operculum long-conic or short-rostrate. Spores 14–16 µm.


Habitat: Soil, rock, open and moderately shaded habitats, lowlands
Elevation: low to high elevations (0-2300 m)

Distribution

V28 652-distribution-map.gif

Man., N.B., Nfld. and Labr., N.S., Ont., Que., Sask., Ala., Ariz., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Pa., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., W.Va., Wis., Wyo., Mexico (Coahuila), Mexico (Jalisco), Mexico (Nuevo León), Mexico (Tamaulipas), s Europe, sw Asia

Discussion

Brachythecium laetum is a widespread, variable, often weedy species of eastern North America. Plants from temporarily flooded ground or growing on dusty and heavily trampled soil are difficult to identify; these have small, short leaves with weak plication especially in branch leaves, the opaque region across leaf base is not conspicuous, and the isodiametric cells are confined mostly to leaf corners. Those plants have been identified as B. salebrosum, but B. salebrosum has autoicous sexual condition and long cells reaching almost the base in proximity to costa. Plants of B. laetum have long-hexagonal cells in the leaf base, often in conspicuous transversal rows, and relatively short cells in the acumen. Occasionally it is difficult to differentiate small plants of B. laetum from xeric habitats and B. acuminatum; important characters of the latter species include small plants, leaves never falcate, thick-walled distal laminal cells, and larger basal cells forming a usually neither pellucid nor opaque or, sometimes, slightly pellucid belt across leaf base. Brachythecium digastrum was synonymized with B. laetum by M. S. Ignatov et al. (2008). The name Brachythecium oxycladum of American authors but not (Bridel) A. Jaeger has been applied to many specimens that are B. laetum.

Selected References

None.

Lower Taxa

None.

"long" is not a number."broad" is not a number.

... more about "Brachythecium laetum"
not separating +
dioicous +, autoicous +  and sexual +
Michael S. Ignatov +
(Bridel) Schimper in P. Bruch and W. P. Schimper +
small +  and smaller +
8um +  and 11um +
short-decurrent +
rounded +  and narrowed +
decurrent +  and rounded +
short to long +
Hypnum laetum +
terete-foliate +
1.2 cm12 mm <br />0.012 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
straight;slightly curved +
cucullate +
brownish orange +
cylindric +
0.2 cm2 mm <br />0.002 m <br /> (0.26 cm2.6 mm <br />0.0026 m <br />) +
specialized +
synoicous +, dioicous +, autoicous +, sexual +  and asexual +
subquadrate +
larger or smaller +
differentiated +
10um +  and 15um +
3 (?) +  and 2 (?) +
discernible +
dioicous +  and sexual +
Man. +, N.B. +, Nfld. and Labr. +, N.S. +, Ont. +, Que. +, Sask. +, Ala. +, Ariz. +, Ark. +, Conn. +, Del. +, D.C. +, Fla. +, Ga. +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, La. +, Maine +, Md. +, Mass. +, Mich. +, Minn. +, Miss. +, Mo. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Pa. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Vt. +, Va. +, W.Va. +, Wis. +, Wyo. +, Mexico (Coahuila) +, Mexico (Jalisco) +, Mexico (Nuevo León) +, Mexico (Tamaulipas) +, s Europe +  and sw Asia +
low to high elevations (0-2300 m) +
not adherent +
Soil, rock, open and moderately shaded habitats, lowlands +
5um (?) +  and 8um (?) +
pointed +
moderate to somewhat +
short-rostrate +  and long-conic +
perfect +  and xerocastique +
hygrocastique +
not plicate +  and crumpled +
in P. Bruch and W. P. Schimper, Bryol. Europ. +
not +  and conspicuous +
differentiated +
brownish orange +
0.7 cm7 mm <br />0.007 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
1.3mm;2.2mm +
concave +  and ovate-triangular +
terete-foliate +
not reddish +
arching +, erect +, ascending +  and creeping +
0 cm0 mm <br />0 m <br /> (7 cm70 mm <br />0.07 m <br />) +
Brachythecium digastrum +
Brachythecium laetum +
Brachythecium +
species +
incrassate +
yellowish +  and brownish +