Stems 0.5–4 (–6) cm, usually comose; sparsely to moderately radiculose. Leaves ovate, ovatelanceolate, or orbicular, distal leaves sometimes enlarged; base green, or if red then same color as rest of leaf, purple, pink, or red sap often present in cell lumina; limbidium indistinct, narrow, yellowish, partially 2-stratose from base to mid leaf (1-stratose in P. marratii); subalar cells not inflated or pink; proximal laminal cells rectangular, longer than medial cells; distal cells short-rhomboidal, lax, 2–4: 1. Capsule with shape variable, ovate, obovate, pyriform, clavate, or turbinate; endostome occasionally fragile and poorly developed, segments with narrow linear to ovate perforations. Spores 10–40 µm, finely papillose (sometimes smooth in P. cyclophyllum), yellow, green, or brown.

Distribution

North America, South America, Eurasia, Africa, Pacific Islands, Australia, arctic and boreal regions of the Northern Hemisphere

Discussion

Species ca. 25 (15 in the flora).

Plants of subg. Ptychostomum are distinctive in a number of characters, especially the 2-stratose margins and the unusual color of the sap in cells of the leaf base. These cells tend to be green, rarely evenly pink or red, but the cell sap is colored, often a bright purple, pink, orange, or red. Usually this occurs as irregular and randomly distributed patches of cells with colored sap; plants of subg. Cladodium do not exhibit this feature. There are two groups of species in subg. Ptychostomum, those with monoicous sexual condition, reduced peristomes and large spores, and those that are dioicous, have more or less well-developed peristomes, and small spores.

Selected References

None.

Lower Taxa

Ptychostomum acutiforme, Ptychostomum arcticum, Ptychostomum calophyllum, Ptychostomum cernuum, Ptychostomum cryophilum, Ptychostomum cyclophyllum, Ptychostomum marratii, Ptychostomum meesioides, Ptychostomum pallens, Ptychostomum rutilans, Ptychostomum schleicheri, Ptychostomum turbinatum, Ptychostomum warneum, Ptychostomum weigelii, Ptychostomum wrightii

Key

1	Stems usually shorter than 3 cm; sexual condition autoicous, polyoicous, or synoicous; peristome reduced; endostome cilia absent or rudimentary; spores usually larger than 24µm	> 2
1	Stems usually (1-)2-4(-10) cm; sexual condition dioicous; peristome well developed (reduced in P. rutilans); endostome cilia usually present; spores smaller than 24 µm	> 8
2	Sexual condition autoicous; leaf limbidium absent or weak, 1-stratose; apices broadly acute to obtuse; costae not reaching apex.	Ptychostomum marratii
2	Sexual condition autoicous, synoicous, or polyoicous; leaf limbidium strong, partially 2-stratose; apices acute to acuminate (obtuse to broadly acute in P. calophyllum); costae usually percurrent or excurrent, sometimes not reaching apex	> 3
3	Sexual condition autoicous or synoicous; spores 18-32 µm; capsules usually red-brown or red at maturity, ovate, broadly ovate, or pyriform	> 4
3	Sexual condition autoicous or polyoicous; spores greater than 24 µm; capsules brown or yellow-brown at maturity, clavate to pyriform, occasionally ovate	> 5
4	Sexual condition autoicous; capsules ovate; leaves ovate-lanceolate; apices acute to acuminate; spores 28-32 µm.	Ptychostomum acutiforme
4	Sexual condition synoicous; capsules broadly ovate to pyriform; leaves ovate; apices acute; spores 18-20(-22) µm.	Ptychostomum wrightii
5	Sexual condition autoicous; capsules ovate; hypophysis thick.	Ptychostomum calophyllum
5	Sexual condition autoicous or polyoicous; capsules pyriform to clavate; hypophysis slender	> 6
6	Sexual condition usually polyoicous; capsules pyriform; spores (32-)36-48(-50) µm.	Ptychostomum warneum
6	Sexual condition autoicous or polyoicous; capsules elongate-pyriform to clavate; spores 24-35 µm	> 7
7	Sexual condition polyoicous, often populations either synoicous or only archegoniate; plants often red or pink; costae excurrent; exostome teeth hyaline distally; spores 24-30(-32) µm.	Ptychostomum arcticum
7	Sexual condition autoicous; plants green or yellow-green; costae percurrent to short-excurrent; exostome teeth yellow throughout or rarely hyaline distally; spores 28-32(-35) µm.	Ptychostomum cernuum
8	Leaf bases strongly, broadly decurrent, decurrencies almost reaching next more proximal leaf; apices acute; costae not reaching apex to short-excurrent.	Ptychostomum weigelii
8	Leaf bases not, weakly, or narrowly decurrent; apices obtuse, acute, or acuminate; costae percurrent to short-excurrent, rarely not reaching apex	> 9
9	Leaves ovate or broadly ovate to suborbicular; apices broadly acute to obtuse; costae not reaching apex to percurrent	> 10
9	Leaves usually ovate to ovate-lanceolate; apices acute or acuminate; costae percurrent to short-excurrent	> 11
10	Plants red, red-green, or red-yellow; leaves strongly concave; costae usually percurrent; spores 16-20 µm.	Ptychostomum cryophilum
10	Plants green or yellow-green; leaves flat or weakly concave; costae usually not reaching apex; spores 14-16 µm.	Ptychostomum cyclophyllum
11	Leaves yellow, yellow-copper, yellow-green, or dull green; bases not or weakly decurrent; margins usually plane proximally; specialized asexual reproduction absent; capsules pyriform or turbinate, symmetric	> 12
11	At least young leaves pink or red tinged; bases not to strongly decurrent; margins revolute proximally; specialized asexual reproduction sometimes present by leaf axil gemmae; capsules elongate-pyriform to clavate, somewhat to strongly curved	> 13
12	Leaves yellow to yellow-copper, older leaves ± imbricate when dry, broadly ovate; medial laminal cells 28-36 µm wide; stems 3-6(-10) cm.	Ptychostomum schleicheri
12	Leaves dull green to yellow-green, all leaves strongly shrunken and contorted when dry, broadly ovate-lanceolate; medial laminal cells 18-25(-30) µm wide; stems (1-)2-4(-6) cm.	Ptychostomum turbinatum
13	Laminal cell walls incrassate, porose; endostome basal membrane less than 1/2 exostome height, cilia reduced or absent.	Ptychostomum rutilans
13	Laminal cell walls thin, not porose; endostome basal membrane 1/2 exostome height, cilia usually long	> 14
14	Capsules strongly curved; exothecial cells elongate, 3-4:1.	Ptychostomum meesioides
14	Capsules somewhat curved; exothecial cells short-rectangular to quadrate, 1-2:1.	Ptychostomum pallens

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