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Montana Field Guide

Montana Field Guides

Variable Hook Moss - Drepanocladus aduncus

Native Species

Global Rank: G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Pleurocarpous (Vitt 1988), usually growing prostrate in soft, loose mats, but commonly in upright tufts, occasionally floating on or submerged in water, green or chartreuse, brown below. Stems usually 2-5 cm in length (up to 40 cm in aquatic plants) (Flowers 1973), possessing a central strand with small cells in the outer layers (Lawton 1971).

Leaves: Curved like a sickle or occasionally straight (FNA 2014), sometimes curved only at the ends of the stems or branches (Lawton 1971), ovate-lanceolate to widely ovate or rounded-deltoid, progressively tapered to the leaf tip, concave, 0.9-5.1 mm in length, 0.4-1.6 mm in width; margins not bordered, smooth or seldom very delicately toothed (FNA 2014), occasionally incurved distally (Lawton 1971); apex acute or tapering to a short to long narrow point; costa solitary, extending to mid leaf or further, but not closely approaching the apex (FNA 2014).

Leaf Cells: Marginal cells unistratose; alar cells short, rectangular or linear (FNA 2014), colorless and swollen, the alar area distinct and stretching from margin to costa or nearly so; median cells long and thin, quite variable in length (Lawton 1971).

Diagnostic Characteristics
Drepanocladus aduncus is often mistaken for Sarmentypnum or Warnstorfia species. Warnstorfia plants usually display red colors when growing in open surroundings, whereas D. aduncus never does. At least a few leaves of most Warnstorfia and Sarmenthypnum species (uncommon in S. trichophyllum) nearly always have rhizoids initials near their tips; this is never the case in D. aduncus (FNA 2014).

Range Comments
Greenland; Canada: AB, BC, MB, NB, NL, NS, NT, ON, PE, QC, SK, YT; USA: AK, AR, AZ, CA, CO, CT, DE, IA, ID, IL, IN, KS, MA, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OR, PA, SD, UT, VA, VT, WA, WI, WV, WY; Mexico; West Indies; Central America; South America; Eurasia; Africa; Indian Ocean Islands; Pacific Islands; Australia (FNA 2014). In Montana, known from Carbon, Carter, Cascade, Choteau, Flathead, Gallatin, Glacier, Granite, Lake, Lewis and Clark, Lincoln, Madison, Mineral, Missoula, Sanders, Stillwater, Teton, and Valley Counties (Elliott 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 46

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

On wet soil, sometimes semi-aquatic (Elliott 2016) in lakes, swamps, and wetlands plentiful in nutrients and minerals (FNA 2014).

Reproductive Characteristics
Dioicous; rarely fruiting (Flowers 1973). Seta 3-6 cm in length. Capsule rounded; urn 2-3 mm in length (Lawton 1971), light ochre in color when ripe (Flowers 1973).

  • Literature Cited AboveLegend:   View Online Publication
    • Elliott, J.C. and A.K. Pipp. 2018. A Checklist of Montana Mosses (1880-2018). Updated 3 January, 2020. 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.
    • Vitt, D. J. Marsh, and R. Bovey. 1988. Mosses, Lichens & Ferns of Northwest North America. Seattle, WA: University of Washington Press. 296 p.
  • 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.
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Citation for data on this website:
Variable Hook Moss — Drepanocladus aduncus.  Montana Field Guide.  .  Retrieved on , from