Pohlia nutans |
Pohlia tundrae |
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nodding pohlia, nodding thread-moss, pohlia moss |
tundra pohlia moss |
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Habit | Plants small to large, green or rarely reddish, dull. | Plants small to medium-sized, green to light green, glossy. |
Stems | 0.5–3.5(–10) cm. |
0.5–2.5 cm. |
Leaves | erect to ± spreading, lanceolate to ovate-lanceolate, 2 mm; base not or scarcely decurrent; margins subentire or more often serrulate to serrate in distal 1/3; costa subpercurrent, percurrent, or rarely short-excurrent; distal medial laminal cells hexagonal to rhomboidal, firm, 50–90 µm, walls moderately thick. |
± spreading, lanceolate to ovate-lanceolate, 0.9–1.5 mm; margins serrulate to serrate in distal 1/3; costa subpercurrent; distal medial laminal cells rhombic to rhomboidal, 45–95 µm, walls thin. |
Seta | orange to orange-brown. |
orange-brown. |
Sexual condition | paroicous, rarely dioicous; perigonial leaves ovate-lanceolate; perichaetial leaves somewhat differentiated, ± long-lanceolate. |
dioicous; perigonial leaves ovate; perichaetial leaves scarcely differentiated, ovate-lanceolate. |
Capsule | inclined 80–100°, orange to orange-brown, slender-pyriform, neck 1/2 urn length; exothecial cells elongate-rectangular, walls straight; stomata superficial; annulus present; operculum conic; exostome teeth yellow to orange-brown, acute-triangular; endostome hyaline or rarely orange-brown, basal membrane 1/2 exostome length, segments tapered apically, broadly keeled, broadly perforate, cilia short to long. |
inclined 95–180°, brown to stramineous, pyriform, neck 1/3 urn length; exothecial cells short-rectangular, walls sinuate; stomata superficial; annulus present; operculum convex-conic; exostome teeth yellow-brown, narrowly triangular-acute; endostome hyaline, basal membrane 1/2 exostome length, segments distinctly keeled, broadly perforate, cilia short to rudimentary. |
Spores | 16–22 µm, finely to distinctly roughened. |
16–23 µm, finely roughened. |
Specialized | asexual reproduction typically absent. |
asexual reproduction usually present when sterile; axillary gemmae 2–8, elongate, extending beyond leaves, yellow, pink, or green, leaf primordia at apex and lower, laminate. |
Pohlia nutans |
Pohlia tundrae |
|
Phenology | Capsules mature spring (Apr–Jun). | Capsules mature summer (Jun–Aug). |
Habitat | Soil banks, logs, tree bases, disturbed places | Acid, relatively humus-rich soil, alpine tundra, stream banks, path banks, heavy metal mine tailings |
Elevation | low to high elevations | low to high elevations |
Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; Africa; Greenland; Eurasia; Mexico (Nuevo León); Australia
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AK; CA; CO; ID; NM; NV; OR; UT; WA; WY; Europe |
Discussion | Pohlia nutans is the most common species of Pohlia in North America, Europe, and elsewhere in the Northern Hemisphere. In contrast to the treatment by A. J. Shaw (1982), P. sphagnicola is not separated here from P. nutans; the type of P. sphagnicola is European. Plants referable to P. sphagnicola, including North American collections, differ in being dioicous and having entire leaves, slightly shorter laminal cells, and smaller spores. The habitat in Sphagnum hummocks is not diagnostic; at least 80% of plants growing in Sphagnum are P. nutans. Pohlia schimperi, a northern form with reddish leaves, also dioicous, is not recognized, as per Shaw. The peristome of Pohlia nutans is as well developed as any in Pohlia, with long, tapered, trabeculate exostome teeth and well-developed endostomes with broadly keeled, widely perforate segments and short to long cilia. The laminal cells are short- to elongate-hexagonal with thickened walls. The only other North American species with relatively thick-walled laminal cells is P. elongata; the cells of P. elongata are typically longer, but there is extensive overlap in sizes. Plants without sporophytes have generally been named P. nutans, although some collections from montane regions may actually be P. elongata; sporophytes of P. elongata have longer necks, as long as or longer than the urns, and reduced peristomes with endostome segments narrowly split along the keel and (usually) no cilia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Pohlia tundrae has linear to oblong gemmae that extend widely from the distal leaf axils and develop in clusters, sometimes densely. The leaf primordia are broadly laminate and flexuose. Lax plants from shaded microsites have narrow pale to whitish gemmae, but plants from more exposed sites have thicker, sometimes reddish gemmae that can appear similar to those of P. drummondii. At high elevations in Yosemite National Park, P. tundrae grows mixed with P. drummondii and the two appear to intergrade, but such intermediate plants have not been seen elsewhere. Occasional plants with very short gemmae can be confused with P. proligera, which typically has smaller, vermicular gemmae with peglike apical leaf primordia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 28, p. 196. | FNA vol. 28, p. 204. |
Parent taxa | Mielichhoferiaceae > Pohlia | Mielichhoferiaceae > Pohlia |
Sibling taxa | ||
Synonyms | Webera nutans, P. sphagnicola | |
Name authority | (Hedwig) Lindberg: Musc. Scand., 18. (1879) | A. J. Shaw: Bryologist 84: 65, figs. 1 – 10. (1981) |
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