Dicranum acutifolium
Dicranum pallidisetum
acuteleaf dicranum moss, sharp-leaf heron's-bill moss
dicranum moss, pale-stalk broom-moss, pale-stalk heron's-bill moss
1.5–7 cm, generally branched above, somewhat tomentose with reddish brown rhizoids.
1–6 cm, tomentose with white or reddish brown rhizoids.
erect-spreading, slightly curled to ± straight when dry, usually with a few undulations in distal part, (3.5–)5–8(–10) mm × 0.5–1 mm, concave below, keeled above, sometimes margins ± involute, lanceolate, narrowly acute to acuminate;
margins serrulate to serrate above;
laminae 1-stratose or with few 2-stratose regions on or near the distal margins;
costa percurrent to shortly excurrent, 1/6–1/4 the width of the leaves at base, smooth to slightly papillose above on abaxial surface, abaxial ridges absent, with a row of guide cells, two stereid bands extending to the apex, adaxial epidermal layer of cells not differentiated, the abaxial layer differentiated;
cell walls between lamina cells not or slightly bulging;
leaf cells smooth to weakly papillose above on abaxial surface;
alar cells 2-stratose, differentiated, often extending to costa;
proximal laminal cells linear-rectangular, pitted, (22–)41–60(–90) × (5–)6–8(–12) µm;
distal laminal cells short-rectangular, irregularly angled or rounded, not pitted, (7–)12–20(–32) × (4–)8–9(–14) µm. Sexual condition pseudomonoicous;
dwarf males on stem rhizoids of female plants;
interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.
often secund, straight or nearly so, often crisped when dry, smooth, 4–8 × 0.5–1 mm, lanceolate, acute, tubulose to apex;
margins entire below, serrulate ot serrate near apex;
laminae 1-stratose or sometimes 2-stratose on distal margins;
costa excurrent, 1/5–1/3 the width of the leaves at base, abaxially papillose or toothed from leaf middle to apex, abaxial ridges absent, with a row of guide cells, stereid bands often present and well-developed in proximal part of leaf, absent in distal 1/4–1/3 of leaf, cells above and below guide cells large and thin-walled;
cell walls between lamina cells not or slightly bulging;
leaf cells smooth or often strongly papillose in distal half of leaf;
alar cells 2-stratose, differentiated, often extending to costa, abaxial ridges absent;
proximal laminal cells linear to rectangular, with or without pits, (26–)58–95(–130) × (10–)12–14(–16) µm;
distal laminal cells quadrate, rounded, irregularly angled or short-rectangular, not pitted, (10–)15–26(–38) × (8–)9–11(–12) µm. Sexual condition dioicous;
male plants as large as female plants;
interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.
1.2–2.5 cm, solitary, yellow to reddish yellow.
1–2.5 cm, solitary or sometimes 2, rarely 3, per perichaetium, yellow, rarely reddish yellow or brown with age.
2–2.7 mm, arcuate, inclined to horizontal, furrowed when dry, rarely slightly strumose, brown to reddish brown;
operculum 1.5–2.5 mm.
1.5–3.5 mm, arcuate, inclined, often with a small struma, strongly furrowed when dry, contracted below mouth, yellow or yellowish brown, rarely reddish yellow or brown with age;
operculum 1.5–2.5 mm.
14–28 µm.
14–20 µm.
Dicranum acutifolium
Dicranum pallidisetum
Dicranum acutifolium has been reported from Colorado by W. A. Weber (1973), but has been deleted from the flora (Weber, pers. comm.). It has also been reported from New Mexico, New York, and Wyoming by W. L. Peterson (1979). This arctic-alpine species is recognized by its erect-spreading leaves, slightly curled when dry, keeled and often weakly undulate above, lanceolate, narrowly acute to acuminate, by its percurrent to shortly excurrent costae, smooth to slightly papillose above, and by its leaf cross section that shows only the abaxial row of cells differentiated, a few 2-stratose marginal cells and the cell walls between lamina cells smooth to slightly bulging. Dicranum acutifolium has often been confused with D. fuscescens but the latter species has a longer, rougher subula that in leaf cross section in the distal half reveals very large and obvious papillae, compared to the smaller and less distinct ones in the former, and margins that are almost completely 2-stratose, while those of D. acutifolium are mostly 1-stratose. It has also been confused with 13. D. brevifolium and for distinctions see discussion thereunder.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Dicranum pallidisetum has often been confused with D. fuscescens, being considered a form of it for many years (R. R. Ireland 1966). Unlike that species, which often occurs at low altitudes below 800 m, D. pallidisetum occurs predominately at high elevations, 800–2000 m, rarely being found as low as 500 m. It is distinguished from D. fuscescens by its tubulose leaves, usually 1-stratose or rarely 2-stratose on the margins, by its costa cross section that shows no stereid bands in the distal 1/3 of the leaf, and by its yellow or yellow-brown capsules that are sometimes 2–3 per perichaetium. In contrast, D. fuscescens has leaves keeled above, usually 2-stratose on both margins, rarely 1-stratose on one margin, stereid bands present throughout the leaf and dark brown to reddish brown capsules that are solitary or rarely 2 per perichaetium.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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