BFNA Title: Orthotrichaceae
Dale H. Vitt
Plants small to robust, dull, dark-green, reddish-brown, or olive-brown, in tufts, cushions, or mats on rocks and trees. Stems erect-ascending and often forked or creeping with numerous, erect, simple or forked branches, interior cells thin-walled and uniform, central strand not present, exterior cells thick-walled. Leaves erect-appressed, spirally-twisted, flexuose, crisped, or contorted when dry, erect-spreading to squarrose-recurved when moist, 5 mm or less, ovate-lanceolate, ligulate-oblong, to lanceolate-linear, rounded-obtuse, acute, occasionally acuminate, apiculate or awned, crowded, ± channeled, usually not decurrent; margins usually plane to revolute, rarely involute to erect, entire or sometimes denticulate near apex; costae strong, ending near apex; distal cells usually 5--15 µm wide and rounded-hexagonal, rarely rectangular, often with incrassate walls and 1--4(--6) conical or forked papillae per cell, rarely smooth or mammillose; basal cells rectangular to elongate-linear, smooth (quadrate in Drummondia and Macrocoma, tuberculate in some species of Macromitrium); alar cells rarely differentiated. Perichaetial leaves sometimes larger than stem leaves. Perichaetia terminal, with further branching occurring by innovations; perigonia large, budlike, terminal or lateral, sometimes occurring on dwarf male plants; brood-bodies occasionally produced. Sexual condition usually goniautoicous or dioecious, rarely pseudautoicous or cladautoicous. Seta 12 mm or less, erect, smooth or rarely rough, dextrose or sinistrorse. Capsule ovate to cylindric-fusiform, erect, symmetric, smooth, or 8-, rarely 16-ribbed, sometimes constricted beneath mouth, immersed, emergent, or exserted; exothecial cells rectangular to elliptic, often differentiated into bands; stomates superficial or immersed, usually below middle of capsule, well developed; operculum convex to conic, rostrate; annulus poorly developed or absent; peristome double, single, rudimentary or rarely lacking, when single endostome lacking, diplolepidous; exostome teeth 16, usually united into 8 pairs, densely papillose or striate, lanceolate, thick, erect, recurved, or reflexed, or sometimes consisting of papillose membrane; endostome segments, 8 or 16 when present, hyaline, thin, linear-lanceolate alternating with exostome teeth or fused to form rudimentary membrane; cilia none; preperistome sometimes present, usually fragmentary. Calyptra mitrate or more rarely cucullate, plicate or smooth, hairy or naked, generally large and conspicuous. Spores isosporous or anisosporous.
Genera 22 (9 in the flora): nearly worldwide.
SELECTED REFERENCES: Vitt, D. H. 1971. A revision of the genus Orthotrichaceae in North America, north of Mexico, Ph.D. Dissertation, University of Michigan, Ann Arbor. Sharp, A. J., H. Crum, and P. Eckel. 1994. The Moss Flora of Mexico, Part Two. Mem. New York Bot. Gard. 69.
1. Plants forming compact cushions on rock; leaves linear; leaf cells with numerous, minute, elliptic, cuticular mounds over both lumens and transverse walls...................................... 1. Amphidium, p. xx
1. Plants forming loose cushions or mats; leaves lanceolate-ligulate or broader; leaf cells smooth or tuberculate to papillose only over lumens.
2. Plants tufted or in cushions; stems erect to ascending; seta twisted to right (in surface view with capsule erect).
3. Distal leaf cells with (3--)4--7 small, conic to clavate papillae; seta slender, long; capsule long-exserted; calyptra cucullate .................................... 9. Zygodon, p. xx
3. Distal leaf cells with 1--3(--4) branched, conic or irregular papillae or smooth; seta stout, short; capsule emergent to shortly exserted; calyptra mitrate.
4. Leaves flexuose-erect; basal leaf cells uniform or only gradually shorter from costa to margin; calyptra covering all of capsule; stomates superficial or immersed in capsule wall 6. Orthotrichum, p. xx
4. Leaves crisped to flexuose; basal leaf cells with strongly differentiated band of shorter, broader, hyaline cells at margin; calyptra covering about half of capsule; stomates superficial in capsule wall......................... 8. Ulota, p. xx
2. Plants in loose mats; stems prostrate or descending, with erect branches; seta twisted to left (in surface view with capsule erect).
5. Leaves with basal border of several rows of elongate, thick-walled cells extending about 1/3--1/2 of leaf length; inner basal cells oblate to rounded, flat . 3. Groutiella, p. xx
5. Leaves with basal marginal cells similar to inner ones or gradually and only slightly longer, without distinct border; inner basal cells elongate to rounded to elliptic, tuberculate, bulging or flat.
6. Calyptra cucullate; leaves oblong, not rugose; spores multicellular.......... 2. Drummondia, p. xx
6. Calyptra mitrate; leaves oblong to ligulate or lanceolate, rugose or not; spores unicellular.
7. Distal leaf cells flat, very small (7--10 µm wide), in diagonal rows; calyptra not plicate, 4--6 lobed at base, naked .. 7. Schlotheimia, p. xx
7. Distal leaf cells bulging, papillose, or flat, small to large (8--)10--16 µm wide, irregularly oriented or in vertical rows; calyptra plicate (or very short, hairy), with numerous lobes, hairy or naked.
8. Capsule cylindric; leaves erect-appressed, straight; margins entire; basal leaf cells oblate-rounded, or elliptic at extreme base................................... 4. Macrocoma, p. xx
8. Capsule ovate to elliptic; leaves loosely arranged, flexuose to twisted, curved or otherwise bent; margins denticulate to entire; basal leaf cells elongate 5. Macromitrium, p. xx