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A Thread Moss - Ditrichum heteromallum

Native Species

Global Rank: G3G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

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General Description
Plants: Acrocarpous, growing in open to crowded clumps of erect shoots (FNA 2007), sometimes well-scattered (Lawton 1971), green with yellow tones above, somewhat ochre or brown below. Stems mostly single, sometimes reaching 10 mm in height, possessing a central strand; rhizoids occurring at the bottom of the stem (FNA 2007).

Leaves: Generally upright or spreading to about 45 degrees (FNA 2007), sometimes tending to point toward the same side of the stem (Lawton 1971), the somewhat egg-shaped base steadily narrowing to a subula, the subula long and with a longitudinal groove; margins flat (FNA 2007) or curved up and inward, sometimes slightly dentate distally but otherwise smooth; costa extending to the apex or beyond (Lawton 1971), largely filling the subula (FNA 2007).

Leaf Cells: Lamina 2 cell-layers thick above; distal laminal and subular cells somewhat long and quadrangular, becoming longer near the bottom of the leaf, occasionally papillose and more often near the leaf tip; margins 2 cell-layers thick in the upper half, 1-layered below; costa in X-section with guide cells in 1 row, a weak ventral stereid band and a well-defined dorsal stereid band (FNA 2007).

Fruit ripens in early- to mid-summer (FNA 2007).

Diagnostic Characteristics
The similar Ditrichum flexicaule often can be distinguished by its marginal cells near mid-leaf, which are isodiametric or nearly so, or lengthened crosswise to the leaf. Those of D. heteromallum are long (Lawton 1971).

Range Comments
North American Range

AK, BC s to OR (FNA 2007). Known in Montana from Flathead and Lewis and Clark Counties (Elliott & Pipp, 2016).

Damp (Elliott & Pipp, 2016), often disrupted, bare, or finely- to coarsely-textured soil and gravel on embankments, roadsides, open spaces in woods (FNA 2007). Ranging in elevation from low-lying areas to occasionally over 4920 feet (Lawton 1971).

Reproductive Characteristics
Dioicous. Perichaetial leaves enveloping the stem (Lawton 1971). Seta, russet, 1-2.5 mm in height, carrying the capsule beyond the perichaetial leaves. Capsule upright, russet, 0.5-1.5 mm in length (FNA 2007), straight, frequently the mouth smaller in diameter (Lawton 1971); peristome single, the 16 teeth (FNA 2007) 2-fid and split almost to the base (Lawton 1971), weakly papillose, light orange. Calyptra draping like a hood (FNA 2007).

Specialized vegetative reproduction occurring rarely from tubers produced by the rhizoids, the tubers looking short and filamentous with enlarged, deformed rhizoid cells (FNA 2007).

  • Literature Cited AboveLegend:   View Online Publication
    • Elliot, J.C., and A.K. Pipp. 2018. A Checklist of Montana Mosses (1880-2018). December 5. Montana Natural Heritage Program, Helena, Montana. 73 pp.
    • Flora of North America Editorial Committee, eds. 2007. Flora of North America North of Mexico. Volume 27. Bryophytes: Mosses, Part 1. Oxford University Press, Inc., NY. xxi + 713 pp.
    • 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
    Do you know of a citation we're missing?
    • 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.
    • Smith, A.J.E. 1980. The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge. 705 pp.
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A Thread Moss — Ditrichum heteromallum.  Montana Field Guide.  .  Retrieved on , from