23. Dicranum viride (Sullivant & Lesquereux) Lindberg, Hedwigia. 2: 70. 1863.
Campylopus viridis Sullivant & Lesquereux in W. S. Sullivant, Musc. Hepat. U.S., 103. 1856; Dicranum fulvum subsp. viride (Sullivant & Lesquereux) Lindberg; D. fulvum var. viride (Sullivant & Lesquereux) Frye
Plants in loose to dense tufts, yellowish to dark green, glossy to dull. Stems 1.5-4.5 cm, sparsely tomentose with whitish to reddish brown rhizoids. Leaves erect-spreading or somewhat falcate-secund, rigid, erect below and flexuose above when dry, smooth, (3-)4-6(-7) × 0.5-0.8 mm, most of the leaf tips broken off, concave below to canaliculate above, from a lanceolate base to a long-acuminate, acute apex (when present); margins entire, sometimes slightly denticulate at apex; laminae 1-stratose or with some 2-stratose regions in patches between margin and costa; costa excurrent, 1/5-1/4 the width of the leaves at base, smooth or slightly rough on abaxial surface in distal half, abaxial ridges absent, with a row of guide cells, two weakly developed stereid bands above and below, not extending above the leaf middle, adaxial and abaxial epidermal layers of cells not differentiated or with a few cells enlarged in both layers; cell walls between lamina cells not or weakly bulging; leaf cells usually smooth; alar cells 1-stratose or with a few 2-stratose regions, well-differentiated, often extending to costa; proximal laminal cells rectangular to short-rectangular, not pitted or with few pits, (11-)33-42(-51) × (7-)9-10(-13) µm; median laminal cells regularly quadrate, not pitted, (9-)15-22(-26) × (5-)7-8(-11) µm; distal laminal cells small, quadrate, not pitted. Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing. Seta 1-1.6 cm, solitary, yellow to reddish brown. Capsule 1.5-2.5 mm, straight, erect, smooth, slightly furrowed when dry, brown to reddish brown; operculum 1-1.5 mm. Spores 9-22 µm.
Capsules mature in spring. Commonly growing on the base of trees (usually deciduous but sometimes coniferous, especially Thuja), rotten logs, stumps, rarely soil and acidic or limestone rock; 40-1400 m; Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Alaska, Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., N.H., N.Y., N.C., Ohio, Pa., Tenn., Vt., Va., W.Va., Wis.; Europe; Asia.
Dicranum viride has been reported from Alaska by I. A. Worley and Z. Iwatsuki (1970) and from Kentucky by J. A. Snider et al. (1988). It is a not uncommon species of the eastern United States and southeastern Canada. It rarely produces sporophytes and is distinctive because of the fragile, deciduous leaf tips, which probably serve as a means of asexual reproduction. It has on occasion been confused with 22. D. fulvum, which has nearly the same distribution, and rarely with 21. D. fragilifolium where their ranges overlap in the Great Lakes region. For distinctions see the discussions under those species.