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juniper haircap moss, juniper polytrichum moss

common haircap moss, polytrichum moss

Habit Plants small to medium to fairly robust, gray-green to bluish green to reddish brown with age, in loose tufts, often forming extensive patches. Plants medium to robust, dark green to brownish with age, in loose or rather dense, tall tufts, often in extensive patches.

(1–)4–5(–10) cm, simple, brownish tomentose only near the base.

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


3–6(–8) mm, densely imbricate, ± erect and almost straight when dry, erect-spreading to widely spreading when moist;

sheath oblong-rectangular, yellowish, tapering to the blade;

blade slender, bluish green and nitid, rather flat, with sharply infolded margins;

marginal lamina 5–7 cells wide, 1-stratose, entire or minutely crenulate, membranous and transparent, enclosing the lamellae and overlapping towards the apex;

costa usually somewhat toothed distally, excurrent, forming a subulate, toothed awn, the awn reddish brown throughout or slightly decolorate at tip;

lamellae bluntly crenate in profile, 6–8 cells high, the marginal cells in cross-section ovate to pyriform, thick-walled, ending in a distinct knob, smooth or rarely faintly papillose, the marginal cells of lateral lamellae (enclosed by the overlapping margins) ovoid and less strongly thickened;

sheath cells 70–100 × 6–10 µm, narrowly rectangular (4–6:1), narrower toward the margin;

cells of the broad marginal lamina transversely elongate, very thick-walled.

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.


(1–)3–5 cm, stout, yellowish to reddish brown.

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

Sexual condition


perigonial rosettes yellowish to reddish green;

perichaetial leaves longer than the foliage leaves, long-sheathing, the blade almost obsolete, ending in a slender yellowish or hyaline awn.


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.


2.5–5 mm, rectangular, longer than wide (1.5–2:1), reddish brown to dark brown, glaucous when fresh, suberect, becoming horizontal when mature, sharply 4-angled and prismatic;

peristome 200–240 µm, divided to 0.6–0.8, the teeth 64, keeled at back.

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.


whitish to light brown, covering the capsule.

golden yellow to brownish, completely enveloping the capsule.


6–10(–12) µm.

5–8(–12) µm.

Polytrichum juniperinum

Polytrichum commune

Habitat Exposed, well-drained, mostly acid soils in old fields and open woods, in openings following forest fire, on trailside banks and road cuts, on thin shallow soil overlying rocks, blowdowns and open ridge tops near timberline, only rarely in moist or wet situations
Elevation low to high elevations
from FNA
AK; AL; AR; AZ; CA; CO; CT; DE; GA; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MT; NC; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; YT; Mexico; Central America; c Asia; Australia; Pacific Islands (New Zealand); Atlantic Islands (Macaronesia); Greenland; n Asia; Europe; s South America; West Indies; Antarctica
[WildflowerSearch map]
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]

Polytrichum juniperinum occurs on a variety of substrates, but primarily in dryer situations than P. commune or P. strictum. It often forms extensive pure stands of a distinctive pale bluish green color from the reflection of light off the thin, membranous margins of the leaves. The narrow leaf blades are widely spreading and have short, reddish awns. Polytrichum juniperinum is common and generally distributed throughout continental North America. In the high Arctic, however, the species is rare and many older reports of it actually pertain to 5. P. hyperboreum (D. G. Long 1985).

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

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.)

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. 138. FNA vol. 27, p. 135.
Parent taxa Polytrichaceae > Polytrichum Polytrichaceae > Polytrichum
Sibling taxa
P. commune, P. hyperboreum, P. jensenii, P. piliferum, P. strictum, P. swartzii
P. hyperboreum, P. jensenii, P. juniperinum, P. piliferum, P. strictum, P. swartzii
Subordinate taxa
P. commune var. commune, P. commune var. perigoniale
Synonyms P. alpestre, P. juniperinum var. alpestre, P. juniperinum var. waghornei
Name authority Hedwig: Sp. Musc. Frond., 89, plate 18, figs. 6–10. (1801) Hedwig: Sp. Musc. Frond., 88. (1801)
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