The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Pennsylvania pogonatum moss

tooth pogonatum moss

Habit Plants small, dull and brownish, scattered on a bright green protonema. Plants medium-sized, in loose tufts or scattered among other bryophytes, green to reddish brown with age.
Stems

0.2–0.6 cm.

to 3(–5) cm, comose from a wiry base, mostly unbranched.

Leaves

2–4 mm, when dry loosely sheathing at the base, the blade narrow, curved and often hooked at the tips, erect-spreading and almost straight when moist;

sheath oblong to oblong-ovate, in leaves near the base of the shoot abruptly contracted to the blade, in distal leaves more gradually tapering, not hyaline-margined, with a narrow strip of incrassate cells at the shoulders;

blade narrowly lanceolate to linear, slenderly acuminate, ending in a short point;

marginal lamina ± plane, variable in width, 1-stratose, irregularly notched-dentate or at times almost entire;

costa smooth or weakly toothed abaxially near the tip;

lamellae 11–16, entire in profile, 4–8 cells high, the marginal cells larger and rounded in section, single or in pairs, smooth;

sheath cells short-rectangular;

cells of lamina 10–12 µm, subquadrate to irregular.

2.5–6 mm, loosely imbricate, erect and somewhat incurved when dry, plane and erect-spreading when moist;

sheath short-ovate, not hyaline-margined, abruptly contracted to the blade, the group of incrassate hinge-cells at the shoulders not much differentiated;

blade rather broadly oblong-lanceolate to linear-lanceolate;

marginal lamina erect, narrowly inflexed when dry, 1-stratose, 1–3 cells wide, toothed nearly to the shoulders with multicellular, uncinate teeth (rarely serrulate, but never entire), the teeth broadly triangular, (1–)3–7-celled, the terminal cell not much larger than the others;

costa percurrent or slightly excurrent as a short, smooth to denticulate point, smooth or sparsely toothed near the tip;

lamellae 20–30, entire or slightly crenulate in profile, 5–7 cells high, the marginal cells thick-walled and coarsely papillose, ± rectangular and flat-topped in section, broader than high, the lumen quadrate;

median sheath cells short-rectangular, thin-walled;

cells on abaxial surface of blade transversely elongate, 25–30 × 12–18 µm, with a median strip of cells shorter and ± isodiametric.

Seta

1–3.5 cm, reddish.

1–3.5(–5) cm, brownish, straight to flexuose.

Capsule

2.5–4 mm, erect or nearly so, sometimes indistinctly angled;

exothecium scabrous, the cells short-rectangular, thick-walled;

operculum obliquely rostrate;

peristome 190–220 µm, divided to 0.8.

2–3 mm, erect to somewhat inclined, brownish;

exothecium mammillose, the cells short-rectangular, incrassate, appearing distinctly pitted in surface view;

peristome 350–450 µm, deeply divided from 0.8 to nearly to the base, the teeth slender, reddish brown with hyaline margins.

Spores

9–12 µm.

18–24 µm.

Pogonatum pensilvanicum

Pogonatum dentatum

Habitat Pioneer on steep banks of moist clay or silt Dry, sunny habitats, silt, sandy or gravelly soil, often in disturbed situations, among stones and boulders, over rock outcrops and on talus slopes
Elevation low to moderate elevations moderate to high elevations
Distribution
from FNA
AL; AR; CT; DE; FL; IA; IL; IN; KS; KY; LA; ME; MO; NH; NJ; NY; OH; OK; PA; TN; TX; VA; VT; WV; NB; NF; NS; ON; PE; QC; Mexico; West Indies
[WildflowerSearch map]
from FNA
AK; MI; NC; NH; NY; OR; VT; AB; BC; NB; NL; NS; NT; NU; QC; YT; e Asia; Greenland; n Asia; n Europe; Atlantic Islands (Iceland)
Discussion

Pogonatum pensilvanicum is widespread in eastern North America. It differs from P. brachyphyllum by the more slender, membranous leaves with irregularly dentate margins and fewer lamellae. The marginal cells of the lamellae are typically in pairs, and they may “bulge out and proliferate, giving rise to masses of what apparently are gemmae” (G. E. Nichols 1937). The calyptra is dirty white and stands out in contrast to the bright emerald-green protonema. When taken up, the texture of the protonemal mat is firm and often quite rubbery. Specimens with more regularly dentate leaf margins are sometimes distinguished as var. torreyanum (Bridel) Paris. Pogonatum pensilvanicum has been reported from South America.

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

Pogonatum dentatum is an arctic-montane species, widespread in the cooler regions of the Holarctic, southward at higher elevations to Oregon, and in eastern mountains to North Carolina. In arctic America, P. dentatum is more common and occurs at lower altitudes than P. urnigerum (D. G. Long 1985). Pogonatum dentatum is distinguished by the rectangular, flat-topped marginal cells of the lamellae in section, compared with the rounded marginal cells of P. urnigerum, with a broadly convex distal wall. The short, mostly unbranched stems, stout, hooked teeth of the leaf margins, and deeply dissected peristome will also serve to distinguish this species in the field. Caducous-leaved forms are frequent in the Arctic. In Nunavut, it is known from Ellesmere Island.

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

Source FNA vol. 27, p. 157. FNA vol. 27, p. 158.
Parent taxa Polytrichaceae > Pogonatum Polytrichaceae > Pogonatum
Sibling taxa
P. brachyphyllum, P. contortum, P. dentatum, P. urnigerum
P. brachyphyllum, P. contortum, P. pensilvanicum, P. urnigerum
Synonyms Polytrichum pensilvanicum, P. brevicaule, P. tenue Polytrichum dentatum, P. capillare
Name authority (Hedwig) P. Beauvois: Mém. Soc. Linn. Paris 1: 461. (1823) (Bridel) Bridel: Bryol. Univ. 2: 122. (1827)
Web links