Dicranum polysetum
Dicranum fulvum
dicranum moss, wavy broom moss, wavy-leaf heron's-bill moss, wavy-leaf moss
boulder broom moss, dicranum moss
4–15 cm, densely tomentose with whitish or reddish rhizoids.
1.5–3.5 cm, sparsely tomentose with light- to reddish brown rhizoids.
erect to spreading, ± flexuose, little changed when dry, strongly undulate, (5.5–)7–9.5(–10.5) × 1–2 mm, lanceolate, concave proximally, keeled above, acute;
margins strongly toothed in the distal half;
laminae 1-stratose;
costa ending before apex, occupying ca. 1/16–1/8 of leaf base, strong, with two toothed ridges distally on abaxial surface, with one row of guide cells, two stereid bands, adaxial epidermal layer of cells not differentiated, abaxial layer with a few cells enlarged;
cell walls between lamina cells not bulging;
leaf cells smooth;
alar cells 2-stratose, well-differentiated, not extending to costa;
proximal laminal cells elongate, pitted, (45–)78–129(–156) × (5–)9–10(–14) µm;
distal laminal cells shorter, sinuose, pitted, (42–)64–68(–115) × (4–)9–10(–13)µm. Sexual condition pseudomonoicous;
dwarf male plants on stem rhizoids of female plants;
interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.
erect-spreading, some weakly falcate-secund, crisped when dry, smooth, (3–)4–5(–7) × 0.5–0.8 mm, some leaf tips broken off, concave below, subtubulose above, narrowly lanceolate to a long, narrow subula occupied mainly by the excurrent costa, apex acute;
margins serrate to serrulate in distal half;
laminae 1- or 2-stratose above, sometimes 2-stratose in patches;
costa excurrent, 1/4–1/3 the width of the leaves at base, abaxially toothed or papillose in distal half, abaxial ridges absent, with a row of guide cells, two stereid bands not extending above the leaf middle, adaxial and abaxial epidermal layers of cells somewhat differentiated or with a few cells enlarged in both layers, cell walls between lamina cells strongly bulging in distal part of leaf lamina;
leaf cells smooth or abaxially prorate above;
alar cells mostly 1-stratose or sometimes with a few 2-stratose cells, distinctly differentiated, often extending to costa;
proximal laminal cells elongate-rectangular, not pitted or with few pits, (19–)24–33(–42) × (4)5–6(9) µm;
distal laminal cells regularly quadrate to short-rectangular, not pitted, (5–)10–11(–16) × (4)5–6(9) µm. Sexual condition dioicous;
male plants as tall as female plants but usually more slender;
interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.
1.5–4 cm, usually aggregate, 3–6 per perichaetium, brown or reddish brown.
1–2 cm., solitary, brown or reddish brown.
2–3.5 mm, arcuate, inclined to horizontal, furrowed when dry, yellowish brown or reddish brown;
operculum 2–4 mm.
1.5–3 mm, straight and erect, smooth, slightly furrowed when dry, reddish brown;
operculum 1.5–2 mm.
12–24 µm.
14–28 µm.
Dicranum polysetum
Dicranum fulvum
W. L. Peterson (1979) recorded Dicranum polysetum from Nunavut. It is one of the largest, most conspicuous, and most easily recognized species in the genus in North America. The species is immediately recognized by the large stems, 4–15 cm, with a dense mat of whitish or reddish tomentum, giving the stems a thickened appearance, by the shiny, strongly undulate, wide-spreading leaves with margins strongly toothed in the distal half and by the clustered sporophytes (3–6 per perichaetium). Microscopically, the species is readily distinguished by the elongate, abundantly pitted cells throughout the leaf and by the toothed ridges on the abaxial surface of the costa in the distal part of the leaf. Dicranum polysetum is one of the few species in North America that has no apparent intergradations with any other species of the genus. It is common in southeastern Canada, northeastern United States, and the Canadian Rocky Mountains, where it extends south to Wyoming and Colorado, occurring in both states in a small number of localities. It is rare west of the Rockies, where it is known from only a few localities in northwestern Montana, southern Idaho and northeastern Washington and Oregon.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Dicranum fulvum has dull, blackish green plants, especially evident from the leaves on the basal part of the stems, leaves crisped when dry, broad costae that cover 1/4–1/3 the width of the leaves at base, laminae that are mostly 2-stratose in the distal half of the leaf, and erect, cylindrical capsules that are slightly furrowed when dry. It is sometimes confused with D. fuscescens but that species has keeled leaves in the distal half, with 2-stratose regions restricted to the margins, and horizontal capsules, whereas D. fulvum has subtubulose leaves, with almost entirely 2-stratose laminae above, and erect capsules. When D. fulvum has some of its leaf apices broken off, which is not uncommon, it can be confused with D. viride, which has the majority of its leaf tips absent. The usual occurrence on rock of plants of D. fulvum as opposed to the usual occurrence on bases of tree trunks of D. viride often gives some clue to their identity. Morphologically, the proximal leaf cells of the two differ: D. fulvum has shorter cells, averaging 24–33 µm, compared to the longer cells of D. viride, averaging 33–42 µm.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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