Cyrtomnium

Holmen

Bryologist 60: 138, figs. 1, 2. 1957.

Etymology: Greek kyrtos, curved or arched, and mnion, moss, alluding to capsules
Treatment appears in FNA Volume 28. Treatment on page 219. Mentioned on page 10, 215, 216, 220, 658.

Plants (0.5–) 2–7 (–20) cm, in tufts or mats. Stems brown or black with age, erect, inclined, arching, or ± plagiotropic, simple, irregularly and sparingly branched, or branched distally, not dendroid; rhizoids brown or reddish-brown, macronemata present, not in longitudinal rows, micronemata present or absent. Leaves often bluish green or green, brownish or reddish when old, crisped or not when dry, erect or erect-spreading, flat or somewhat undulate when moist, ovate or broadly elliptic, 1–2 (–2.5) mm; base not to long-decurrent; margins plane, green or bluish green, 1-stratose, entire; apex obtuse, acute, or rounded, apiculate or not; costa subpercurrent or percurrent, distal abaxial surface smooth; medial laminal cells ± isodiametric or short-elongate, 22–45 µm, often in longitudinal and diagonal rows, weakly collenchymatous, walls weakly pitted; marginal cells differentiated, linear or short-linear, sometimes rhomboidal, in 1–3 rows. Specialized asexual reproduction from fragile stem fragments, plants sometimes breaking only near stem apex. Sexual condition dioicous. Seta single, brown, 3–4 cm, straight. Capsule strongly inclined to horizontal, brown, cylindric, 4–5 mm; stomata phaneroporous; operculum short-apiculate; exostome yellow; endostome pale-yellow, segments free. Spores 13–25 µm.

Distribution

n North America, Europe, Asia

Discussion

Species 2 (2 in the flora).

The phaneropore stomata in Cyrtomnium are unique in Mniaceae, and the reduced endostome cilia are also unusual for the family. These mosses are distinguished morphologically and by habitat preference. In both species, plant stems break easily, and field populations often consist of loose fragments and plants anchored to the substratum, intermixed with other mosses. The outer laminal cell walls have a hygroscopic coating and, as a result, fragments float in water. Thus, local dispersal in these species may be by moving water or by wind, which apparently moves fragments in tundra. Plants of both species often display bluish green leaves. Cyrtomnium is a genus mainly of Arctic and subarctic regions. However, C. hymenophylloides is found far southward as a relict in lowland gorges or in mountains.

Selected References

None.

Key

1 Leaf marginal cells mainly linear, in (1-)2-3 rows; leaf bases not or short-decurrent. Cyrtomnium hymenophylloides
1 Leaf marginal cells mainly short-linear in 1 (or 2) rows; leaf bases long-decurrent. Cyrtomnium hymenophyllum
... more about "Cyrtomnium"
blackish +, orange-yellow +, reddish-brown +, yellowish-brown +, yellowish green +, red +, brown +  and yellow +
not +  and apiculate +
Rounded (?) +, Acute (?) +  and Obtuse (?) +
Norton G. Miller† +  and Gert Steen Mogensen +
Holmen +
long-decurrent +
cucullate +
strongly inclined;horizontal +
cylindric +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
undifferentiated +
2 (?) +  and 1 (?) +
nodulose +
subpercurrent +
toothed +
n North America +, Europe +  and Asia +
Greek kyrtos, curved or arched, and mnion, moss, alluding to capsules +
lanceolate-acuminate +
crowded +  and distant +
0.2 cm2 mm <br />0.002 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
reddish +, brownish +, green +  and bluish green +
elliptic +, ovate +, undulate +, not +  and crisped +
larger +  and small +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
bluish green +  and green +
dioicous +, synoicous +  and sexual +
short-elongate +  and isodiametric +
rostrate +, mammillate +, apiculate +, hemispheric +  and conic +
reddish-brown +  and brown +
smaller +  and larger +
straight +
elongate +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
spheric +
not dendroid +, branched +  and simple +
black +  and brown +
arching +, inclined +  and erect +
phaneroporous +
Cyrtomnium +
Mniaceae +
blunt +  and sharp +
dioicous +  and sexual +