Timmia comata Lindberg & Arnell; T. norvegica var. comata (Lindberg & Arnell) H. A. Crum

Plants generally smaller and more delicate than those of var. norvegica. Leaves 2-6 mm, 0.5-0.6 mm wide at mid-limb; cells of mid-limb lamina 6-10(-11) × 6-9(-10) µm; costa excurrent, smooth on abaxial surface of sheath, smooth or slightly papillose on abaxial surface of the limb, with one-several teeth at back near the apex; base of costa pale and not strongly attached to the stem; stem tips often with loose deciduous clusters of almost linear leaves (ca. 3 × 0.1-0.2 mm).

Calcareous areas, often on shaded limestone cliffs near rivers in Arctic and boreal regions, intermixed with other mosses, including other taxa of Timmia; low to moderate elevations (0-1500 m); Greenland; Nfld. and Labr. (Nfld.), N.W.T., Nunavut, N.S., Que, Yukon; Alaska; Eurasia (Scandinavia, Switzerland, Poland, Russia); Atlantic Islands (Iceland).

Variety excurrens is known also as a Quaternary subfossil from New York and Vermont. Variety excurrens is not known to occur with sporophytes, but the deciduous leaves no doubt act as vegetative propagules.