Schistidium apocarpum
Schistidium crassipilum
schistidium moss
thickpoint grimmia
1.2–12 cm, central strand weak or absent.
1–3.5(–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 slightly curved when dry, ovate-lanceolate, sharply keeled distally, 1.7–3.3 mm, 1-stratose with 2-stratose striae or patches or occasionally 2-stratose distally;
margins recurved to well just before the apex, often less recurved to nearly plane on part of one side of leaf, usually denticulate near apex, usually 2-stratose or 3-stratose;
apices acute;
costa percurrent or excurrent as a denticulate, usually decurrent awn, abaxial surface often papillose;
basal marginal cells quadrate or short-rectangular, transverse walls often somewhat thicker than longitudinal walls, often trigonous;
distal laminal cells usually rounded or short-rectangular, 8–9 µm wide, weakly 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.
red-brown, sometimes orange-brown, elongate-cylindric to cylindric, 0.8–1.4 mm;
exothecial cells mostly elongate, mixed with angular-isodiametric cells, walls unevenly thickened and somewhat curved, often trigonous;
stomata absent or few;
peristome patent to squarrose, sometimes twisted, 300–450 µm, red, densely to finely papillose, entire or strongly perforated.
11–14(–19) µm, granulose or smooth.
8–11 µm, granulose or verruculose.
Schistidium apocarpum
Schistidium crassipilum
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.)
Schistidium crassipilum is distinguished by its unevenly 2-stratose leaves, its elongate-cylindrical to cylindrical capsules, and the mostly elongate exothecial cells, with their cell walls unevenly thickened and somewhat curved. S. Flowers (1973) may have illustrated this species (as Grimmia apocarpa), although details of the exothecial cells that would confirm this are absent in his illustrations.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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