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juniper haircap moss, juniper polytrichum moss

arctic 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 small to fairly robust, green to attractive chestnut brown with age.

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

2–6(–10) cm, simple or more commonly fasciculately branched, whitish tomentose only at base.


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.

3–6 mm, crowded in distal half stem, erect and closely appressed when dry, erect-spreading when moist;

sheath rectangular, abruptly contracted to the blade;

blade linear-lanceolate, rather flat, with sharply infolded margins, channeled at the apex and tapering to the bicolored awn;

marginal lamina 7–9 cells wide, 1-stratose, entire, membranous, infolded and overlapping, completely enclosing the lamellae;

costa excurrent with low blunt teeth abaxially near apex, the awn coarsely spinulose at the base, brown in the basal 1/3 to 1/2, hyaline distally;

lamellae 5–9 cells high, the marginal cells in section ovoid, somewhat larger than cells below, thin-walled or very slightly thickened at apex;

median sheath cells 45–90 × 12–15 µm, narrowly rectangular, thin-walled;

cells of marginal lamina 10–15 × 24–45 µm, thick-walled, obliquely oriented and shorter toward the margin and thin-walled.


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

rather short for plant size, 1.2–3 cm, reddish.

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 elongate, with hyaline lamina and long, tapering awn.


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.

2.3–3 mm, ovoid-rectangular (1.2–2:1), somewhat broader at base, sharply 4(–5)-angled, erect, becoming inclined to horizontal when mature;

peristome 150–230 µm, divided to 0.6, the teeth pale brownish, acute.


whitish to light brown, covering the capsule.


6–10(–12) µm.

15–17 µm.

Polytrichum juniperinum

Polytrichum hyperboreum

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 Open sandy or stony ground, ridges, moraines, and open tundra, and in deep masses on stream banks and margins of lakes and ravines
Elevation low to high elevations low to moderate elevations (0-1500 m) (low to moderate elevations (0-4900 ft))
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 FNA
AK; LB; NT; NU; QC; YT; Greenland; n Europe (Scandinavia); n Asia (Russia)

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.)

Polytrichum hyperboreum is a handsome species, widespread in arctic America. Sporophytes are commonly produced. In Nunavut, it is known from Baffin, Ellesmere, and Melville islands. The most distinctive characters are the branching habit, channeled leaf apex, and the distinctive bicolored awn, which is coarsely and thickly spinulose at the base, brownish below and hyaline in the distal 1/2. In P. juniperinum, P. strictum, and P. piliferum the awns are ± evenly roughened throughout to almost smooth. It differs from these species also in the rather thin-walled, ovoid marginal cells of the lamellae, and the broad marginal laminae overlapping and completely enclosing the lamellae.

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

Source FNA vol. 27, p. 138. FNA vol. 27, p. 138.
Parent taxa Polytrichaceae > Polytrichum Polytrichaceae > Polytrichum
Sibling taxa
P. commune, P. hyperboreum, P. jensenii, P. piliferum, P. strictum, P. swartzii
P. commune, P. jensenii, P. juniperinum, P. piliferum, P. strictum, P. swartzii
Synonyms P. alpestre, P. juniperinum var. alpestre, P. juniperinum var. waghornei P. piliferum var. hyperboreum
Name authority Hedwig: Sp. Musc. Frond., 89, plate 18, figs. 6–10. (1801) R. Brown: Chlor. Melvill., 36. (1823)
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