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common haircap moss, polytrichum moss

awn haircap moss, polytrichum moss

Habit Plants medium to robust, dark green to brownish with age, in loose or rather dense, tall tufts, often in extensive patches. Plants small to medium, glaucous green to reddish brown, in loose tufts.
Stems

(2–)5–10(–70) cm, stiffly erect to decumbent, mostly simple or rarely forked, bracteate proximally, densely to rather distantly leafy.

(0.5–)1–4 cm tall, rather wiry, unbranched, comose at the tips, whitish tomentose only near the base.

Leaves

6–8(–12) mm, erect or erect-spreading when dry, flexuose, with distinctly recurved tips, spreading to broadly recurved when moist, or the blade sharply squarrose-reflexed from the base;

sheath oblong to elliptic, involute-tubular and clasping the stem, often golden yellow and highly nitid, abruptly contracted to the narrowly lanceolate blade;

marginal lamina plane or erect, narrow, 2–3(–7) cells wide, toothed from the base of blade to the apex, the teeth unicellular, embedded in the margin;

costa toothed abaxially near the apex, excurrent, ending in short, rough awn;

lamellae crenulate in profile, 5–9 cells high, the margin distinctly grooved as seen from above, with 2 rows of paired, projecting knobs, the marginal cells in section narrow or more typically enlarged and wider than those beneath, retuse to deeply notched (rarely divided by a vertical partition), ± thick-walled and brownish, smooth;

sheath cells 60–90 × 10–13 µm, elongate-rectangular to linear (as much as 20:1), narrower toward the margins;

cells of the marginal lamina 10–15 µm wide, subquadrate.

(2–)3–4 mm, erect, straight and slightly incurved when dry, erect-spreading when moist;

sheath ovate, ± contracted to the blade;

blade linear-lanceolate, turgid, with sharply infolded margins, the leaf apex abruptly contracted to the base of the awn;

marginal lamina 5–8 cells wide, 1-stratose, membranous, entire to finely serrulate toward the apex, enclosing the lamellae and overlapping in distal half or more;

costa typically smooth abaxially, long-excurrent as a spinulose-toothed, hyaline awn;

lamellae in profile crenulate-dentate to serrulate, with crenulations directed towards the leaf apex, (4–)6–8 cells high, the marginal cells in section conic to distinctly pyriform, terminating in a distinct knob, the marginal cells of the lateral lamellae ovoid, thinner-walled;

sheath cells 60–80 × 10–15 µm, elongate-rectangular (4–6:1);

cells of marginal lamina transversely elongated, ± irregular and sinuous, smaller toward the margins and obliquely oriented, especially approaching the apex, thick-walled.

Seta

5–9 cm, stout, yellowish to reddish brown.

1–3 cm, stout, flexuose, reddish brown.

Sexual condition

dioicous;

perichaetial leaves with a long, scarious-margined sheath and blade greatly reduced, gradually narrowed to a finely acuminate tip, the margins toothed, denticulate to subentire, the costa short- to long-excurrent, roughened to almost smooth.

dioicous;

perigonia intense wine-red;

perichaetial leaves a little longer than foliage leaves, with hyaline lamina and longer awns.

Capsule

3–6 mm, short-rectangular to cubic, brown to dark reddish brown, glaucous when fresh, sharply 4-alate, inclined to horizontal;

peristome 250 µm, divided to 0.6, the teeth 64, pale.

2.5–3.5 mm, short to almost cubic (1.5–2:1), inclined, becoming horizontal when mature;

peristome rather short, 110–180(–200) µm, divided to 0.6, the teeth about 64, obtuse.

Calyptra

golden yellow to brownish, completely enveloping the capsule.

dirty white to light brown, enclosing the capsule.

Spores

5–8(–12) µm.

9–12 µm.

Polytrichum commune

Polytrichum piliferum

Habitat Shallow well-drained sandy or gravelly soil over rocks and boulders in sunny situations, often associated with Cladonia, in road cuts, old fields, burned over areas, heaths, rocky ridges and moraines, and in dry alpine tundra and late snow areas northward
Elevation low to moderate elevations
Distribution
from USDA
Mexico; Widely distributed in the North America; throughout temperate and boreal latitudes in the Northern Hemisphere; Pacific Islands (New Zealand); Australia
[WildflowerSearch map]
from FNA
AK; AL; AZ; CA; CO; CT; IA; ID; IN; KS; KY; LA; MA; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NY; OH; OR; PA; SD; TN; UT; VA; VT; WA; WI; WV; WY; HI; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; YT; South America; Australia; Greenland; Atlantic Islands (Falkland Islands, Macaronesia); Asia; Europe; Antarctica
[WildflowerSearch map]
Discussion

Widely distributed in the North America, throughout temperate and boreal latitudes in the Northern Hemisphere, Mexico, Pacific Islands (New Zealand), Australia.

The only North American species likely to be confused with Polytrichum commune is Polytrichastrum pallidisetum. When sterile, Polytrichum commune is easily distinguished by cross-sections of the leaves, particularly by the greatly broadened costa, and the notched marginal cells of the lamellae. In Polytrichastrum pallidisetum the marginal cells of the lamellae are broadened and shallowly retuse, but not distinctly notched, and in Polytrichum commune the arc of guide cells (seen in section below mid-point of blade) is broad, 18–24 cells wide, compared with 8–12 cells wide in Polytrichastrum pallidisetum. When capsules are present, the two species can be distinguished at a glance. A striking form of Polytrichum commune growing in wetlands, var. uliginosum, has greatly elongate stems and tightly sheathing, glossy leaf bases, the blades are flexuose and squarrose-recurved. Recent European genetic studies (R. J. Bijlsma et al. 2000) suggest that it should be recognized as a separate species.

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

Polytrichum piliferum is easily recognized by its habit, growing in short, loose reddish brown clumps, each plant crowned by a whitish tuft of intertwined hyaline awns. The intensely colored, wine-red antheridial rosettes are remarkably flower-like in appearance. The lamella marginal cells are pyriform in section, ending in a distinct knob, except for the lamellae standing in the shade of the inflexed lamina. The leaves of P. piliferum are smooth abaxially and abruptly contracted to the base of the awn; P. juniperinum is a larger plant with reddish rather than hyaline awns; P. hyperboreum is typically fastigiately branched, the leaves with a channeled leaf apex, tapering to a bicolored awn. In Nunavut, it is known from Baffin and Melville islands.

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

Key
1. Plants (2-)5-10(-70) cm; apical cells of lamellae broader than those beneath, in section deeply grooved; inner perichaetial leaves not much longer than the foliage leaves, toothed distally, ending in a rather short, roughened awn
var. commune
1. Plants to 6 cm; marginal cells of lamellae narrow, in section shallowly grooved; inner perichaetial leaves ribbon-like, exceeding the foliage leaves, denticulate to subentire, gradually tapering to long, nearly smooth awn
var. perigoniale
Source FNA vol. 27, p. 135. FNA vol. 27, p. 140.
Parent taxa Polytrichaceae > Polytrichum Polytrichaceae > Polytrichum
Sibling taxa
P. hyperboreum, P. jensenii, P. juniperinum, P. piliferum, P. strictum, P. swartzii
P. commune, P. hyperboreum, P. jensenii, P. juniperinum, P. strictum, P. swartzii
Subordinate taxa
P. commune var. commune, P. commune var. perigoniale
Name authority Hedwig: Sp. Musc. Frond., 88. (1801) Hedwig: Sp. Musc. Frond., 90. (1801)
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