Pohlia wahlenbergii
Pohlia obtusifolia
pale nodding-cap moss, pale pohlia, Wahlenberg's pohlia moss
blunt-leaf pohlia, blunt-leaf thread-moss, obtuseleaf pohlia moss
0.8–10 cm.
0.3–0.8 cm.
laxly spreading to more stiffly erect, lanceolate to ovate-lanceolate, 0.6–1.2 mm;
margins weakly to strongly serrulate in distal 1/3;
costa ending well before apex;
distal medial laminal cells laxly and broadly hexagonal to rhomboidal, 65–110 µm, walls thin.
erect to ± spreading, broadly lanceolate, 0.7–1.4 mm;
margins serrulate to serrate in distal 1/3;
costa subpercurrent;
distal medial laminal cells hexagonal or broadly rhombic, lax, 30–70 µm, walls thin.
orange-brown.
orange-brown.
dioicous;
perigonial leaves ovate;
perichaetial leaves weakly differentiated, lanceolate.
paroicous;
perichaetial leaves scarcely differentiated, broadly lanceolate.
inclined ± 180°, brown to red-brown, sometimes stramineous, short-pyriform to urceolate, neck less than 1/3 urn length;
exothecial cells isodiametric, walls sinuate;
stomata immersed;
annulus absent;
operculum short- to long-conic;
exostome teeth light brown to red-brown, triangular-acute;
endostome hyaline to yellow, basal membrane 1/2 exostome length or slightly longer, segments tapered apically, distinctly keeled, broadly perforate, cilia long, nodulose.
inclined 160–180°, stramineous to orange-brown, broadly pyriform, neck 1/3 urn length;
exothecial cells elongate-rectangular, walls straight;
stomata superficial;
annulus present;
operculum bluntly conic;
exostome teeth yellow to brown, bluntly acute;
endostome hyaline, basal membrane low, scarcely exceeding capsule rim to 1/3 exostome length, segments narrow, weakly keeled, broadly perforate, cilia absent.
15–21 µm, finely roughened.
17–25 µm, distinctly roughened.
asexual reproduction absent.
asexual reproduction absent.
Pohlia wahlenbergii
Pohlia obtusifolia
Pohlia wahlenbergii is one of the most geographically widespread and common species of the genus. The leaves are pale whitish, decurrent, and have lax, thin-walled cells. The species varies greatly in size from very slender delicate plants in suboptimal habitats to large and deep cushions in cold high altitude and latitude sites. Large plants of P. wahlenbergii typically have red stems and sometimes reddish pigmentation to the leaves as well. Some authors refer large expressions to var. glaciale (or P. glaciale), but gradation in size and pigmentation is completely continuous, and different collectors draw the line between the typical variety and var. glaciale at different points. The exothecial cell walls in capsules of this species are somewhat collenchymatous.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Plants of Pohlia obtusifolia with sporophytes are generally small, but some sterile colonies in late snowmelt areas at high elevations form deeper cushions. When plants are sterile, the subtly cucullate leaves provide a clue to their identity; they are similar to those of P. drummondii, but the stems tend to be less red, the laminal cells are broader and thinner walled, and axillary gemmae are absent. Pohlia obtusifolia is paroicous (unlike P. drummondii, which is dioicous) and the capsules are barrel-shaped, with straight, rectangular walls (sinuate in P. drummondii and other gemmiferous species). The peristome of P. obtusifolia is relatively reduced, with slenderly triangular exostome teeth that are weakly pitted basally, a low endostomial basal membrane, and narrow segments that are weakly keeled but broadly perforate.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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