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nodding pohlia, nodding thread-moss, pohlia moss

pohlia moss

Habit Plants small to large, green or rarely reddish, dull. Plants very small to large, as scattered plants or deep, sometimes extensive, turfs.
Stems

0.5–3.5(–10) cm.

0.1–10 cm, not complanate-foliate, often bearing subfloral innovations below the gametangia.

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.

with dorsal and lateral not differentiated, erect to spreading, narrowly lanceolate to ovate-lanceolate [rarely linear-lanceolate], 0.6–3.5 mm;

base decurrent or not;

margins plane (strongly revolute in P. cardotii and P. crudoides), finely serrate to serrulate near apex, rarely entire;

apex acute (sometimes short-acuminate in P. melanodon);

costa ending well before apex, subpercurrent, percurrent, or rarely short-excurrent;

distal medial laminal cells elongate-hexagonal, rhombic, or linear-rhomboidal, sometimes narrowly vermicular;

marginal cells undifferentiated or slightly narrower and longer than medial cells.

Seta

orange to orange-brown.

single (multiple in P. robertsonii), stramineous to orange-brown, straight or bent.

Sexual condition

paroicous, rarely dioicous;

perigonial leaves ovate-lanceolate;

perichaetial leaves somewhat differentiated, ± long-lanceolate.

dioicous, paroicous, or rarely autoicous;

perigonia and perichaetia terminal (perigonia rarely lateral in P. longibracteata);

perigonial leaf apex acute to long-acuminate;

perichaetial leaves same size as vegetative leaves or sometimes strongly differentiated, lanceolate to narrowly linear-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 0–180°, narrowly cylindric to broadly pyriform or urceolate, 1–6[–10] mm, neck sometimes 1+ times urn length;

exothecial cells near mouth in 1–3+ rows, medial cell walls straight or sinuate;

stomata superficial to immersed;

annulus absent or present, revoluble;

operculum convex, short- to long-conic, sometimes short-rostrate;

peristome double [rarely absent], 4:2:4–6(–8);

exostome white, pale yellow to brown, or sometimes dark reddish brown, teeth triangular to lanceolate, sometimes irregular [rarely reduced or absent], trabeculate or not, pitted basally, coarsely papillose distally (coarsely papillose throughout in P. crudoides);

endostome basal membrane low to high, sometimes scarcely exceeding capsule rim, segments narrow to wide, strongly to weakly or scarcely keeled, rarely reduced to rudimentary projections, broadly to narrowly perforate or less often not, cilia absent or 1–3.

Spores

16–22 µm, finely to distinctly roughened.

Specialized

asexual reproduction typically absent.

asexual reproduction common, by spheric to ovoid rhizoidal tubers or axillary filiform to bulbiform gemmae.

Pohlia nutans

Pohlia

Phenology Capsules mature spring (Apr–Jun).
Habitat Soil banks, logs, tree bases, disturbed places
Elevation low to high elevations
Distribution
from FNA
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
[WildflowerSearch map]
from USDA
North America; Mexico; Central America; South America; Europe; Asia; Africa; Pacific Islands (New Zealand); Australia
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.)

Species ca. 85 (32 species in the flora).

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

Key
1. Axillary gemmae present
→ 2
1. Axillary gemmae absent
→ 14
2. Gemmae with peglike leaf primordia
→ 3
2. Gemmae with broadly laminate (leaflike) leaf primordia
→ 8
3. Plants glossy
→ 4
3. Plants dull
→ 5
4. Gemmae oblong-linear to linear-vermicular, leaf primordia elongate, erect.
P. proligera
4. Gemmae isodiametric to oblong, leaf primordia inconspicuous, incurved.
P. andrewsii
5. Gemmae oblong, knobby in outline, leaf primordia absent.
P. flexuosa
5. Gemmae spheroid, obconic, or linear, not knobby in outline, leaf primordia present
→ 6
6. Gemmae spheroid.
P. camptotrachela
6. Gemmae oblong or obconic to linear
→ 7
7. Gemmae oblong or obconic, leaf primordia 2-5, conspicuous.
P. annotina
7. Gemmae narrowly linear, leaf primordia 1 or 2, inconspicuous.
P. flexuosa
8. Gemmae 2-8 per leaf axil, narrowly elongate, oblong-bulbiform, or obconic
→ 9
8. Gemmae 1 or 2 per leaf axil, bulbiform
→ 11
9. Gemmae elongate, extending beyond leaves.
P. tundrae
9. Gemmae oblong, obconic, or spheroid, shorter than leaves
→ 10
10. Gemmae obconic to oblong.
P. andalusica
10. Gemmae spheroid to obovate.
P. bulbifera
11. Gemmae oblong or elliptic to subglobose, leaf primordia small, stiff, restricted to apex or rarely 1 or 2 proximally.
P. filum
11. Gemmae bulbiform, leaf primordia large, flexuose, at gemma apex and proximally
→ 12
12. Plants dull; leaves slightly contorted when dry.
P. rabunbaldensis
12. Plants glossy; leaves unaltered when dry
→ 13
13. Plants dark green to reddish; leaves ± spreading.
P. drummondii
13. Plants whitish; leaves ± erect.
P. beringiensis
14. Leaf margins strongly recurved to revolute
→ 15
14. Leaf margins plane
→ 16
15. Leaves narrowly long-lanceolate; medial laminal cells linear-hexagonal, walls thin, not porose.
P. crudoides
15. Leaves ovate-lanceolate; medial laminal cells rhombic, walls thick, ± porose.
P. cardotii
16. Sexual condition paroicous
→ 17
16. Sexual condition dioicous (very rarely paroicous)
→ 22
17. Setae multiple.
P. robertsonii
17. Setae single
→ 18
18. Medial laminal cells lax, hexagonal or broadly rhombic, walls thin.
P. obtusifolia
18. Medial laminal cells firm, hexagonal to rhomboidal or vermicular, walls thin or thick
→ 19
19. Plants dull; laminal cells hexagonal to rhomboidal
→ 20
19. Plants shiny; laminal cells linear-vermicular
→ 21
20. Capsule necks 1/2 urn length; endostome segments broadly perforate, cilia present.
P. nutans
20. Capsule necks 1/2 to 1 time urn length; endostome segments narrowly to not perforate, cilia absent to rudimentary, rarely long.
P. elongata
21. Leaves long-lanceolate; endostome segments narrowly to not perforate, cilia absent to rudimentary.
P. longicolla
21. Leaves lanceolate to elliptic; endostome segments broadly perforate, cilia present, short to long.
P. cruda
22. Capsules inclined 0-20°; endostome segments weakly keeled, slightly tapered, cilia absent.
P. erecta
22. Capsules inclined 35-180°; endostome segments distinctly keeled, tapered apically, cilia present or absent
→ 23
23. Leaf bases long-decurrent; medial laminal cells rhombic to rhomboidal.
P. ludwigii
23. Leaf bases not or scarcely decurrent; medial laminal cells linear, hexagonal, or rhomboidal
→ 24
24. Capsules narrowly cylindric, inclined 35-90°; endostome segments narrowly to not perforate, cilia absent to rudimentary.
P. bolanderi
24. Capsules pyriform to urceolate, inclined 80-180°; endostome segments broadly perforate, cilia present
→ 25
25. Annulus present; exothecial cells rectangular
→ 26
25. Annulus absent; exothecial cells isodiametric
→ 28
26. Plants green or rarely reddish, dull; laminal cells short- hexagonal.
P. nutans
26. Plants pale green to green, glossy; laminal cells linear-rhomboidal to linear-vermicular
→ 27
27. Plants somewhat glossy; leaf margins serrulate at apex; medial laminal cells 65-110 µm.
P. lescuriana
27. Plants very glossy; leaf margins coarsely serrate at apex; medial laminal cells 110-145 µm.
P. pacifica
28. Medial laminal cells laxly rhomboidal
→ 29
28. Medial laminal cells linear-hexagonal to linear-rhomboidal or broadly rhomboidal
→ 31
29. Plants very small, reddish; stems 0.2-0.4 cm; stomata superficial.
P. atropurpurea
29. Plants small to large, green to whitish, rarely reddish when very large; stems 0.3-10 cm; stomata deeply immersed
→ 30
30. Plants dark green; stems 0.3-1 cm.
P. melanodon
30. Plants whitish, sometimes reddish when very large; stems 0.8-10 cm.
P. wahlenbergii
31. Plants medium-sized to large; leaves wide-spreading; perigonial leaves to 6 mm.
P. longibracteata
31. Plants small to rarely medium-sized; leaves erect to erect-spreading; perigonial leaves to 3 mm
→ 32
32. Stomata superficial or slightly immersed
→ 33
32. Stomata immersed
→ 34
33. Stems 0.3-1.5 cm; leaves erect-spreading; medial laminal cells linear, 6-9 µm wide.
P. brevinervis
33. Stems 0.2-0.4 cm; leaves erect-spreading to spreading; medial laminal cells laxly and broadly rhomboidal, 10-12 µm wide.
P. atropurpurea
34. Stems green to pale orange or pink; leaves spreading; plants dull.
P. columbica
34. Stems cherry red; leaves erect; plants glossy.
P. vexans
Source FNA vol. 28, p. 196. FNA vol. 28, p. 193.
Parent taxa Mielichhoferiaceae > Pohlia Mielichhoferiaceae
Sibling taxa
P. andalusica, P. andrewsii, P. annotina, P. atropurpurea, P. beringiensis, P. bolanderi, P. brevinervis, P. bulbifera, P. camptotrachela, P. cardotii, P. columbica, P. cruda, P. crudoides, P. drummondii, P. elongata, P. erecta, P. filum, P. flexuosa, P. lescuriana, P. longibracteata, P. longicolla, P. ludwigii, P. melanodon, P. obtusifolia, P. pacifica, P. proligera, P. rabunbaldensis, P. robertsonii, P. tundrae, P. vexans, P. wahlenbergii
Subordinate taxa
P. andalusica, P. andrewsii, P. annotina, P. atropurpurea, P. beringiensis, P. bolanderi, P. brevinervis, P. bulbifera, P. camptotrachela, P. cardotii, P. columbica, P. cruda, P. crudoides, P. drummondii, P. elongata, P. erecta, P. filum, P. flexuosa, P. lescuriana, P. longibracteata, P. longicolla, P. ludwigii, P. melanodon, P. nutans, P. obtusifolia, P. pacifica, P. proligera, P. rabunbaldensis, P. robertsonii, P. tundrae, P. vexans, P. wahlenbergii
Synonyms Webera nutans, P. sphagnicola
Name authority (Hedwig) Lindberg: Musc. Scand., 18. (1879) Hedwig: Sp. Musc. Frond., 171. (1801)
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