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Brachythecium moss, rough-stalk feather-moss, rough-stalk ragged-moss

acute Brachythecium moss

Habit Plants large, in moderate to dense mats, green, light green, or yellowish to brownish. Plants medium-sized to large, in loose to dense mats, yellowish to brownish.
Stem(s)

leaves erect-appressed or sometimes erectopatent, closely to loosely imbricate, ovate to ovate-triangular, broadest at 1/9–1/5 leaf length, slightly to occasionally strongly concave, not to weakly plicate, 1.8–3 × 0.8–1.6 mm;

base rounded, broadly or sometimes narrowly decurrent;

margins plane, often recurved proximally, occasionally elsewhere, serrulate to serrate;

apex short to moderately acuminate;

costa to 50–75% leaf length, moderately strong, terminal spine absent, sometimes small tooth present;

alar cells short-rectangular, enlarged, 30–45 × 18–23 µm, walls thin, region conspicuous, of 5–10 × 5–10 cells, pellucid;

laminal cells linear, 60–140 × 7–11 µm;

basal cells to 11–14 µm wide, region in 2–4 rows.

leaves erect to erect-spreading, loosely imbricate to somewhat spaced, broadly to narrowly ovate-triangular, broadest at 1/10 leaf length or below, not concave, not or slightly plicate, 2–2.8 × 0.8–1.2 mm;

base rounded, inconspicuously short-decurrent;

margins plane, occasionally recurved distally, minutely and evenly serrulate to subentire;

apex gradually tapered to narrow acumen or gradually acuminate, occasionally short-apiculate;

costa to 60–70% leaf length, strong, terminal spine absent;

alar cells subquadrate or short-rectangular, small to enlarged, 15–30 × 10–14 µm, walls moderately thick, region somewhat differentiated or almost undifferentiated, usually inconspicuous, of 4–7 × 5 cells, pellucid;

laminal cells linear, 60–135 × 8–11 µm, walls not or moderately porose;

basal cells to 20–25 × 10–13 µm, region in 2–5 rows.

Branch leaves

with base often asymmetric;

margins usually recurved below broadest part of leaf.

with margins often recurved at base, usually less serrulate;

basal laminal cells almost undifferentiated or alar region of 2–7 cells, pellucid, (often hidden by recurved margins).

Seta

reddish orange, 1.5–2.5(–3) cm, rough.

red-brown, 2–4 cm, smooth.

Sexual condition

autoicous.

autoicous.

Capsule

strongly inclined to horizontal, red-brown, ovoid to elongate, curved, 2–2.5 mm;

annulus separating by fragments;

operculum conic.

inclined to horizontal, red-brown, ovate, slightly curved, 15–20 mm;

annulus separating by fragments;

operculum conic.

Spores

12–18 µm.

13–18 µm.

Brachythecium rutabulum

Brachythecium acutum

Habitat Tree bases, rotten logs, litter and soil in forests, shaded rock, soil on lawns Wet soil, peat, fens, swamps, rotten logs in swampy forests
Elevation low to high elevations (0-2800 m) (low to high elevations (0-9200 ft)) low to moderate elevations (0-1000 m) (low to moderate elevations (0-3300 ft))
Distribution
from FNA
AL; AR; CT; DC; DE; ID; IL; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NY; OH; PA; RI; SD; TN; VA; VT; WI; WV; WY; BC; NB; NL; NS; ON; QC; Central America; Eurasia; n Africa; Atlantic Islands; Pacific Islands (Hawaii, New Zealand); Australia
[WildflowerSearch map]
from FNA
AK; CA; CO; DE; IA; ID; IL; IN; ME; MO; MT; ND; NE; NJ; NY; OH; PA; SD; UT; WY; BC; MB; NF; NU; ON; QC; SK; YT
Discussion

Brachythecium rutabulum is a large forest moss forming rather dense, shiny mats with many crowded sympodial branches. Its robust stature and the frequent presence of sporophytes with rough setae often allow for confident field identification. Brachythecium rivulare is equally robust, but can be distinguished in the field by the somewhat dendroid appearance; the sympodial shoots in B. rivulare are usually only slightly branched proximally. Under a microscope, the distinctive inflated alar cells readily separate B. rivulare from B. rutabulum. Alar cells in B. rutabulum have a quite different appearance: they are enlarged in a group just proximal to decurrencies, whereas close to marginal cells, they are narrow and chlorophyllose. More slender plants of B. rutabulum are easy to confuse with Sciuro-hypnum curtum (see discussion under 10. S. curtum).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Brachythecium acutum is distinguished by the evenly tapered, triangular, and weakly or not plicate leaves. Brachythecium acutum has been treated as an eplicate form of B. salebrosum (for example, H. A. Crum and L. E. Anderson 1981). This conclusion may have been based on the fact that sometimes, especially in drier habitats, its alar cells are relatively smaller and form a square group; this pattern is also known for the Eurasian B. mildeanum (Schimper) Schimper. However, optimally developed B. acutum is distinct in having homogeneous areolation across the leaf base, quite regularly triangular leaves, minute teeth along leaf margins, not or very weakly plicate leaves, and unusually long setae.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 28, p. 413. FNA vol. 28, p. 423.
Parent taxa Brachytheciaceae > Brachythecium Brachytheciaceae > Brachythecium
Sibling taxa
B. acuminatum, B. acutum, B. albicans, B. asperrimum, B. bolanderi, B. boreale, B. brandegeei, B. campestre, B. cirrosum, B. coruscum, B. erythrorrhizon, B. frigidum, B. jacuticum, B. laetum, B. rivulare, B. rotaeanum, B. ruderale, B. salebrosum, B. turgidum, B. udum
B. acuminatum, B. albicans, B. asperrimum, B. bolanderi, B. boreale, B. brandegeei, B. campestre, B. cirrosum, B. coruscum, B. erythrorrhizon, B. frigidum, B. jacuticum, B. laetum, B. rivulare, B. rotaeanum, B. ruderale, B. rutabulum, B. salebrosum, B. turgidum, B. udum
Synonyms Hypnum rutabulum Hypnum acutum, B. pseudocollinum
Name authority (Hedwig) Schimper: in P. Bruch and W. P. Schimper, Bryol. Europ. 6: 15. (1853) (Mitten) Sullivant: Icon. Musc., suppl., 99. (1874)
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