Ulota C. Mohr, Ann. Bot. 2: 540. 1806.
[referring to curled leaves of some species]
Dale H. Vitt
Plants to 5.5 mm. Stems erect or rarely creeping, ± branched. Leaves contorted-crisped to slightly twisted and erect-curved when dry, erect-spreading to spreading-flexuose when moist, 1--1.4 mm, oblong- to linear-lanceolate, usually from an ovate base, acuminate, acute, or narrowly obtuse, base usually clasping stem; margins entire, plane or reflexed; costa ending near apex or rarely excurrent; distal cells 6--13 µm wide, hexagonal-rounded to elliptic, with very incrassate walls and conical papillae, sometimes smooth; interior basal cells radiating from insertion, rectangular-elongate to elliptic, often nodose, very thick-walled, usually orange, sharply grading to thin-walled, hyaline, quadrate marginal cells. Brood bodies rarely present, if so, then only at tips of leaves. Perichaetial leaves larger. Sexual condition autoicous or rarely dioicous. Seta 1.5--10 mm. Capsule 0.6--3.2 mm, fusiform-cylindric, ovate-oblong or rarely obovate, lightly 8-plicate at mouth to moderately 8-ribbed entire length, fully exserted, mouth puckered or capsule ± constricted beneath mouth, gradually contracted to seta through long neck; stomates superficial; peristome double or single; exostome teeth 8, sometimes split to 16, ± perforate at tips, finely and densely papillose to papillose-striate, reflexed or erect and flexuose; endostome segments 8 or lacking, smooth, reticulate or papillose-striate, incurved; preperistome never present. Calyptra smooth, hairy, mitrate, short-conic to conic, not plicate, usually deeply split several times at base. Spores isomorphic.
Species ca. 60 (9 in the flora): temperate in distribution; North America, South America, Europe, Asia, Australia, Pacific Islands (New Zealand).
The genus Ulota consists of approximately 60 species of which over half are restricted to the Southern Hemisphere. Generally, New Zealand, Japan, and western North America are especially rich in species. Ecologically the species are primarily found either in wet, shaded coniferous forests, particularly in areas of high rainfall, or in subalpine areas where they grow on small trees. Ulota is closely related to the genus Orthotrichum. Ulota differs by its conic calyptra shape, highly differentiated basal leaf cells, crisped leaves, superficial stomates, and lack of brood bodies on the leaf lamina. A few species show a close resemblance to the genus Macromitrium in having creeping stems, similar basal cells and calyptrae. The North American species can be divided into four groups: (1) dioicous species, producing brood-bodies---U. phyllantha; (2) species with a single, erect-flexuose peristome and leaves not much crisped---U. drummondii and U. coarctata; (3) species with a double peristome and the exostome teeth reflexed---U. crispa, U. curvifolia, U. hutchinsiae, U. barclayi, and U. obtusiuscula; and (4) species with creeping branched stems---U. megalospora.