Brachythecium udum

I. Hagen

Kongel. Norske Vidensk. Selsk. Skr. (Trondheim) 1908(3): 4, plate 1, fig. 1. 1908.

Synonyms: Brachythecium mildeanum var. udum (I. Hagen) Mönkemeyer B. salebrosum subsp. udum (I. Hagen) J. J. Amann
Treatment appears in FNA Volume 28. Treatment on page 427. Mentioned on page 415, 416, 422, 424.

Plants medium-sized to large, in dense mats, green to pale stramineous. Stems to 8 cm, ascending to upright, terete-foliate, quite loosely irregularly pinnate, often almost unbranched, branches to 7 mm, straight, terete-foliate. Stem-leaves erect, occasionally erectopatent, closely imbricate, ovate to ovatelanceolate, broadest at 1/12–1/9 leaf length, concave, not to somewhat plicate, 1.9–2.4 × 1–1.3 mm; base slightly rounded, inconspicuously decurrent; margins recurved usually only near base, entire to slightly serrulate; apex gradually tapered, often abruptly acuminate; costa to 40–70% leaf length, stronger near base, often much weaker distally, terminal spine absent; alar cells short-rectangular, enlarged, 20–30 × 20 µm, walls moderately thin, region slightly differentiated or enlarged, indistinctly or rarely distinctly delimited, of to 5 × 6 cells, pellucid; laminal cells linear, 70–115 × 7–9 µm, walls not or moderately porose; basal-cells 12–18 µm wide, region in 2 or 3 rows. Branch leaves smaller, narrower. Sexual condition dioicous. Sporophytes unknown.


Habitat: Wet soil, rock over soil, Arctic and alpine habitats
Elevation: low elevations (100 m)

Discussion

Brachythecium udum occurs in Siberia and northern Europe; it has been found in collections by W. C. Steere from Alaska (Noluck Lake), and probably occurs in northern Canada. The Alaska specimen was identified as B. albicans, which is superficially rather similar, but the different patterns of basal areolation easily distinguish them. Alar cells of B. udum are more differentiated than in B. acutum, and in permanently wet habitats, the alar cells can be rather strongly enlarged. Poor branching and commonly upright growth are also characteristic of B. udum.

Selected References

None.

Lower Taxa

None.

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

... more about "Brachythecium udum"
separating +  and not separating +
dioicous +, autoicous +  and sexual +
Michael S. Ignatov +
I. Hagen +
12um +  and 18um +
short-decurrent +
rounded +  and narrowed +
decurrent +  and rounded +
short to long +
terete-foliate +
dioicous +  and sexual +
cucullate +
straight +  and curved +
pendent +, horizontal +  and inclined +
cylindric;elongate;cylindric;elongate;ovate +
specialized +
synoicous +, dioicous +, autoicous +, sexual +  and asexual +
short-rectangular +
enlarged +
differentiated +
3 (?) +  and 2 (?) +
discernible +
Alaska +  and n Eurasia +
low elevations (100 m) +
not adherent +
Wet soil, rock over soil, Arctic and alpine habitats +
7um (?) +  and 9um (?) +
weaker +  and stronger +
pointed +
moderate to somewhat +
entire +  and slightly serrulate +
short-rostrate +  and conic +
perfect +  and xerocastique +
hygrocastique +
not plicate +  and crumpled +
Kongel. Norske Vidensk. Selsk. Skr. (Trondheim) +
enlarged +
differentiated +
darker +  and redbrown +
1.9mm;2.4mm +
erectopatent +  and erect +
concave +, ovate +  and ovatelanceolate +
unbranched +  and terete-foliate +
not reddish +
ascending +  and upright +
0 cm0 mm <br />0 m <br /> (8 cm80 mm <br />0.08 m <br />) +
Brachythecium mildeanum var. udum +  and B. salebrosum subsp. udum +
Brachythecium udum +
Brachythecium +
species +
incrassate +
green +  and pale stramineous +
medium-sized;large +