Blytt's Thyme Moss - Mnium blyttii
MNPS Threat Rank
Plants: Acrocarpous, growing in open to crowded clumps of upright shoots (Flowers 1973). Stems deep russet, mostly 2-5 cm tall, rarely to 7 cm (FNA 2014), mostly unbranched, possessing a central strand; rhizoids brown and tomentose proximally (Lawton 1971).
Leaves: Wavy and a little twisted, curved, or bent when dry (FNA 2014), spreading when wet, 1.3-2 mm in width (Lawton 1971), 2-4 mm in length, the upper leaves much larger (FNA 2014) and more crowded than those below (Crum and Anderson et al. 1981), green to deep green, widely egg-shaped to elliptic, sometimes with ovate tendencies, ending in an acute and sometimes curved or more broadly-angled leaf tip, forming an apiculus or occasionally a small-toothed cusp; base extending a little to well-down the stem; margins flat, becoming russet over time, smooth to slightly dentate in the distal half, seldom toothed further below on the margin, the teeth small and usually single; costa usually reaching or nearly reaching the leaf tip, occasionally shorter, without teeth distally on the upper part of the dorsal surface (FNA 2014), red (Lawton 1971).
Leaf Cells: Margins mostly of 1 cell-layer, seldom with short stretches of 2 layers, the cells long and narrow in up to 3 rows, often becoming somewhat russet with time (FNA 2014), the marginal teeth of 1 cell (Lawton 1971); medial cells of the lamina about as wide as long or, more often, slightly elongated, a little larger toward the center than near the margins, occasionally in somewhat indistinct longitudinal (but not oblique) rows (FNA 2014).
Fruit ripens in the summer (FNA 2014).
Even plants of M. blyttii with smooth-appearing leaf margins should have some leaves that have a few marginal cells with a small bulge at their distal end facing anteriorly, separating them from Rhizomnium and Cinclidium (FNA 2014).
North American Range
AK to NU, BC and AB s to WA, UT, and NM, also CA (FNA 2014). Known in Montana from Flathead, Gallatin, Glacier, Hill, Jefferson, Lake, Madison, Mineral, Missoula, Park, and Sanders Counties (Elliott and Pipp 2016).
Shaded and damp soil, humus and stone, sometimes on bluffs (FNA 2014); montane (Lawton 1971).
Dioicous. Antheridia with heads plate-like. Perichaetial bracts longer than vegetative leaves. Seta 3-5 cm tall (Lawton 1971), solitary. Capsule sometimes reaching 5 mm in length, ochre (FNA 2014), level to drooping, with a short neck; stomata sunken, with guard cells partly visible (Lawton 1971), occurring in the neck (Crum and Anderson et al. 1981); exostome green with yellow tones (FNA 2014), papillose; endostome segments wide, with cilia in groups of 2-3. Calyptra draping like a hood (Lawton 1971).
- Literature Cited AboveLegend: View Online Publication
- Crum, H.A. and L.E. Anderson. 1981. Mosses of Eastern North America. 2 volumes. Columbia University Press, New York. 1328 pp.
- Elliott, J.C. and A.K. Pipp. 2018. A Checklist of Montana Mosses (1880-2018). December 20th. Montana Natural Heritage Program, Helena, Montana. 73 pp.
- Flora of North America Editorial Committee, eds. 2014. Flora of North America North of Mexico. Volume 28. Bryophytes: Mosses, Part 2. Oxford University Press, Inc., NY. xxi + 702 pp.
- Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University, Provo, Utah. 567 p.
- Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botanical Laboratory. Japan: Yamabuki-cho, Shinjuku-ku, Tokyo. 362 pages plus appendices.
- Additional ReferencesLegend: View Online Publication
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- Lawton, E. 1971. Keys for the Identification of the Mosses on the Pacific Northwest. Reprinted from 'Moss Flora of the Pacific Northwest'. Published as Supplement No. 2 of the Journal of the Hattori Botanical Laboratory. Nichinan, Miyazaki, Japan. 66 pp.
- Malcolm, B., N. Malcolm, J. Shevock, and D. Norris. 2009. California Mosses. Nelson, New Zealand: Micro-Optics Press. 430 pp.
- Vitt, D. J. Marsh, and R. Bovey. 1988. Mosses, Lichens & Ferns of Northwest North America. Seattle, WA: University of Washington Press. 296 p.