Dicranum polysetum
Dicranum ontariense
dicranum moss, wavy broom moss, wavy-leaf heron's-bill moss, wavy-leaf moss
Ontario dicranum moss
4–15 cm, densely tomentose with whitish or reddish rhizoids.
3–8 cm, densely tomentose below with 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.
falcate-secund, flexuose, contorted when dry, slightly undulate, (5–)6.5–9(–10) mm × 1–1.5 mm, concave below, keeled above, from a lanceolate base to a long-acuminate apex;
margins plane, strongly serrate above;
laminae 1-stratose, rarely with 2-stratose regions on margins or near costa;
costa percurrent to slightly excurrent, 1/6–1/5 the width of the leaves at base, papillose to spinose above on numerous, low abaxial ridges, with a row of guide cells, two thick, well-developed stereid bands above and below extending to apex, adaxial epidermal layer of cells not differentiated, the abaxial layer differentiated;
cell walls between lamina cells not bulging or weakly bulging;
leaf cells prorate on abaxial surface, sometimes papillose adaxially;
alar cells 2-stratose, rarely 3-stratose in parts, differentiated, not extending to costa;
proximal laminal cells rectangular, pitted, (22–)40–64(–126) × (2–)7–8(–10) µm;
distal laminal cells short-rectangular to rectangular, not pitted, ± in longitudinal rows, marginal cells usually more elongate, some distal cells with long toothlike projections, scattered on abaxial surface, (7–)12–18(–42) × (5–)8–12(–16) µm. Sexual condition pseudomonoicous;
dwarf males on stem rhizoids of female plants;
interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.
1.5–4 cm, usually aggregate, 3–6 per perichaetium, brown or reddish brown.
2–3.5 cm, often aggregate 2–5 per perichaetium, sometimes solitary, yellow, brown or reddish yellow.
2–3.5 mm, arcuate, inclined to horizontal, furrowed when dry, yellowish brown or reddish brown;
operculum 2–4 mm.
2–3 mm, arcuate, inclined to horizontal, furrowed when dry, yellow to light brown;
operculum 1.5–3 mm.
12–24 µm.
9–20 µm.
Dicranum polysetum
Dicranum ontariense
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.)
W. L. Peterson (1979) recorded Dicranum ontariense from Alberta. This is a North American endemic species that was previously mistaken for D. drummondii Müller Hal., a predominately Eurasian species which was unknown on this continent until it was discovered just recently on the Aleutians Islands. Peterson (1977) clarified the taxonomic position of D. ontariense, while P. Isoviita (1977) amplified on the complex nomenclatural details of why it must be recognized as a species distinct from D. drummondii. The main distinguishing features of D. ontariense are the dark to light green, dull, falcate-secund, flexuose tipped, slightly undulate leaves, contorted when dry, keeled above from a lanceolate base to a long-acumination, the leaf apices papillose to spinose above on abaxial surface, the laminae 1-stratose except for occasional 2-stratose regions on margins, the leaf margins plane, strongly serrate above, and the usually multiple sporophytes, 2–5 per perichaetium.
This species is sometimes confused with an environmental form of Dicranum undulatum that has nearly percurrent costae and ± acute apices. The aggregate setae of D. ontariense will immediately distinguish it from that form, which has solitary setae. The dull leaves that are contorted when dry, and the leaf apices that are long-acuminate, abundantly spinose on the abaxial surface, are other superficial features to distinguish it from D. undulatum, which has shiny, usually broadly acute, smooth or serrulate leaf apices. Also, on occasion, D. ontariense can be confused with large forms of D. condensatum when sterile. The thin-walled, short-rectangular to quadrate distal-median cells in more or less regular rows of the former will distinguish it from the latter, which has irregularly shaped cells that are thick-walled and usually not in well defined rows. When fruiting, the aggregate setae on some of the plants of D. ontariense will immediately distinguish it from D. condensatum, which has solitary setae.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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