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juniper haircap moss, juniper polytrichum 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 sized to tall and robust, in loose to compact tufts, arising from a horizontal underground rhizome.

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

loosely to densely leafy distally, bracteate proximally, rhizoidous at base or rarely wooly-tomentose throughout.


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.

with differentiated sheath and blade;

sheath entire, hyaline-margined, often highly nitid (glossy), with a well-developed hinge-tissue at the junction of sheath and blade;

marginal lamina narrow, plane or erect, sharply toothed with stout, unicellular teeth, or entire, broadened and ± sharply inflexed, enclosing the lamellae;

costa short-excurrent or prolonged as a long, spinulose awn;

lamellae numerous, closely-spaced, the marginal cells in section distinctly differentiated, pyriform, flat-topped, or retuse, smooth.


(1–)3–5 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.


male plants with conspicuous rosettes formed by the broadly overlapping, apiculate perigonial bracts, commonly innovating and producing several successive male inflorescences per shoot;

perichaetial leaves typically long-sheathing, the sheath broadly hyaline-margined, with a weakly-developed and greatly abbreviated blade.


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.

4(–5)-angled, often somewhat broader toward the base, alate and prismatic with knife-edge angles after the operculum is shed, reddish to purplish brown, glaucous in fresh capsules, suberect when young but becoming sharply bent at the attachment to the seta and almost horizontal;

hypophysis discoid, sharply delimited from the urn by a deep basal constriction;

stomata rather few and confined to the constriction;

exothecial cells bulging-mammillose, often transversely elongate, with a sharply defined, circular or slit-like pit in the outer wall;

operculum umbonate, with a short beak;

peristome teeth 64, pale, single, with a thin vertical keel and delicate spur-like projections in the inner face;

epiphragm thin and delicate, remaining attached to the peristome teeth, the margin thicker and dissected into pendent lobes alternating with the peristome teeth.


whitish to light brown, covering the capsule.

with a densely interwoven, matted felt of hairs, enveloping the whole capsule and entwined beneath.


6–10(–12) µm.

small, smooth (minutely echinulate with SEM).

Polytrichum juniperinum


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

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.)

Species ca. 70 (7 in the flora).

Polytrichum is characterized by a unique set of tightly correlated sporophytic characters. The capsules are sharply angled with a discoid hypophysis separated from the body of the capsule by a deep basal constriction, and a glaucous appearance when fresh (see E. Lawton 1971, frontisp.). The exothecial cells are bulging-mammillose, with a sharply-defined pit, and the peristome and epiphragm are of the pterygodont type (S. O. Lindberg 1868; Gary L. Smith 1971, 1974). Polytrichum species are distinct genetically from other members of the family, suggesting an early origin for this lineage. Capsules with bulging-mammillose, pitted exothecial cells, discoid hypophysis, and spores echinulate with “Christmas-tree” projections are already present in the Late Cretaceous fossil genus Eopolytrichum (A. S. Konopka et al. 1997). Two groups of Polytrichum species are represented in our area, one with narrow, toothed, ± erect leaf margins (sect. Polytrichum), and the other with broad, entire, sharply inflexed leaf margins, enclosing and sheltering the adaxial lamellae (sect. Juniperifolia).

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

1. Marginal lamina narrow, mostly erect, the margins sharply toothed to subentire; cells of the marginal lamina ± isodiametric
→ 2
1. Marginal lamina broad, membranous, sharply inflexed and overlapping, enclosing the lamellae, the margins entire or minutely crenulate; cells of the marginal lamina transversely elongate-rectangular, thick-walled
→ 4
2. Marginal cells of lamellae in section single or geminate, usually broader than tall, rounded-quadrate, flat-topped or asymmetrical, the margin flat-topped or shallowly crenulate, without projecting knobs.
P. swartzii
2. Marginal cells of lamellae in section single, retuse to distinctly notched (rarely divided by a vertical partition), the margin distinctly grooved as seen from above, with 2 rows of paired, projecting knobs
→ 3
3. Stems (2-)5-10(-70) cm; leaves with blade squarrose-recurved when moist, not caducous, margins strongly toothed; capsule rectangular.
P. commune
3. Stems 3-12 cm; leaves straight or weakly recurved when moist, the blade caducous, margins entire or finely serrulate; capsule short-rectangular to cubic.
P. jensenii
4. Leaf sheath ovate; blade abruptly contracted to a long, hyaline awn.
P. piliferum
4. Leaf sheath elliptic to rectangular; blade tapering to a short brownish or bicolored awn
→ 5
5. Plants fastigiately branched; awns roughly toothed at the base, bicolored, reddish brown at base, hyaline in distal 1/2; marginal cells of lamellae ovoid, ± thin-walled.
P. hyperboreum
5. Plants simple; awns roughened to subentire, concolorous, brownish throughout (or hyaline only at extreme tip); marginal cells of lamellae in section pyriform, thick-walled especially in the apex
→ 6
6. Stems brownish tomentose only near base; leaves longer, 3-6(-8) mm; capsules to 2 times longer than broad.
P. juniperinum
6. Stems densely whitish tomentose; leaves short, 2-5(-6) mm; capsules cubic.
P. strictum
Source FNA vol. 27, p. 138. FNA vol. 27, p. 133. Author: Gary L. Smith Merrill.
Parent taxa Polytrichaceae > Polytrichum Polytrichaceae
Sibling taxa
P. commune, P. hyperboreum, P. jensenii, P. piliferum, P. strictum, P. swartzii
Subordinate taxa
P. commune, P. hyperboreum, P. jensenii, P. juniperinum, P. piliferum, P. strictum, P. swartzii
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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