Schistidium apocarpum
Schistidium cryptocarpum
schistidium moss
schistidium moss
1.2–12 cm, central strand weak or absent.
0.8–2.5 cm, central strand distinct.
erect or curved, rarely (falcate-) secund when dry, ovate-lanceolate, sharply keeled distally, (1.3–)1.7–2.5(–3.2) mm, 1-stratose or rarely 2-stratose in striae distally;
margins usually recurved throughout or to just before the apex, usually denticulate distally, 1 or 2-stratose;
apices acute or sub-obtuse;
costa percurrent or excurrent as a smooth or weakly denticulate, occasionally decurrent awn, abaxial surface often papillose;
basal marginal cells usually quadrate;
distal laminal cells mostly short-rectangular, 8–10 µm wide, smooth, sinuose.
erect or curved, rarely falcate, imbricate when dry, lanceolate to ovate-lanceolate, strongly keeled distally, (0.9–)1.4–2(–2.3) mm, 1-stratose;
margins usually recurved to just before the apex, proximally often more broadly recurved on one side of leaf, distal 1/3 often plane, smooth, 1-stratose with 2-stratose sections;
apices acute or sub-obtuse;
costa excurrent as a denticulate, flexuose, usually strongly decurrent awn, often embracing part of the lamina, smooth;
basal marginal cells short-rectangular, occasionally with transverse walls thicker than longitudinal walls;
distal cells mainly short-rectangular or quadrate, 7–10(–11.5) µm wide, smooth, usually strongly sinuose.
autoicous.
autoicous.
dark red or brown, short-cylindric, 0.7–1.3 mm;
exothecial cells usually quadrate, sometimes mixed with short-elongate or oblate cells, thin-walled, usually trigonous;
stomata present;
peristome patent or erect, often twisted, 350–600(–700) µm, red, densely papillose, usually perforated.
orange-brown or reddish brown, campanulate, 0.5–0.6 mm;
exothecial cells short-elongate or isodiametric, often more or less quadrate, thin-walled or slightly thickened, small trigones usually present;
stomata present;
operculum rostrate;
peristome rudimentary, consisting of basal segments, or absent, yellowish, papillose.
11–14(–19) µm, granulose or smooth.
8–12 µm, verruculose.
Schistidium apocarpum
Schistidium cryptocarpum
Although H. H. Blom (1996) considered Schistidium apocarpum to be restricted in the flora area to the eastern portions of North America, it is more widespread and scattered across the continent. The denticulate leaf margins, papillose abaxial costal surface, short-cylindrical capsules, and the thin-walled, often evenly quadrate exothecial cells are distinguishing characters. The long peristome teeth are also useful in identifying S. apocarpum. In good condition the peristome can only be confused with that of S. trichodon, which differs in the darker, often black color of its plants, the peristome teeth often forming a dome, and the cylindrical capsules that retain the columella.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The long, usually strongly decurrent awns and the campanulate capsules absent a distinct peristome separate Schistidium cryptocarpum from other arctic species of the geunus. Mogensen and Blom provided further details on this species. It should be confused only with S. flaccidum, a more southern species, which differs in having a mamillate rostrum and a cupulate capsule.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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