Jennings: Manual of Mosses — 8. Orthotrichaceae 107 



5. Orthotrichum pumilum Dickson 

 Densely cespitose, dark green, tufts less than 1 cm high; stems only a few 

 mm high; leaves erect-spreading, lance-oblong, when dry imbricated and 

 straight, obtuse to short-acuminate, margin recurved; upper leaf-cells rounded- 

 hexagonal, rather thin-walled for the genus, relatively rather large, minutely 

 papillose, the basal cells larger, rectangular and smooth; costa strong, ending a 

 little below the apex: seta very short, capsule immersed, small, when moist 

 oval-oblong with a distinct neck, when dry narrower, constricted below the 

 mouth, 8-plicate, yellowish to orange; stomata immersed; exothecial cells quad- 

 rate to rectangular-hexagonal, becoming at the mouth much smaller, rounded, 

 and rather obscure; peristome-teeth 8, bigeminate, yellowish-pellucid, triangu- 

 lar-lanceolate, papillose, when dry reflexed, the segments alrriost as long, lance- 

 subulate, 8 in number; calyptra smooth, short, inflated, lustrous, with few or 

 no hairs, light yellow; spores .012-. 015 mm, mature in spring: autoicous. 



On trunks of trees; Europe, Asia, Algeria, and, in North America, from 

 southeastern Canada to Tennessee and westward to Idaho and Utah. 



Rare in our region. Washington Co.: Linn and Simonton. (Porter's Catalogue). 



6. Orthotrichum obtusifolium (Schrader) Bridel 



Plate LXIII 



Small yellowish green tufts up to about 8-10 mm high; leaves appressed 

 when dry, spreading when moist, about 1.5-2.5 mm long, oblong-ovate to 

 lingulate, entire, decurrent, trough-shaped with plane margins, obtuse to 

 broadly acute; costa strong but ending below apex; thick-walled brood-bodies 

 abundant on apical upper surface of some leaves; upper leaf-cells thick-walled, 

 rounded, basal marginal short-rectangular, basal median somewhat larger and 

 elongate-rectangular, middle and upper cells with low blunt papillae. 



On deciduous tree bark, from southern Canada and New England to 

 Maryland and from Alaska to our Southwest. 



Washington Co.: "On fallen ash tree," near Washington, Linn and Simonton, Feb. 

 10 and Mar. 16, 1894 (figured). 



4. Ulota Mohr 



Autoicous, rarely dioicous: mostly forming cushions on living trees: stems 

 often creeping with erect or ascending branches, radiculose; leaves mostly 

 (except U. americana) crisped or contorted when dry, mostly spreading to 

 squarrose, from a broadly concave base lance-linear, carinate, with margins 

 mostly revolute below; costa percurrent or nearly so; basal cells narrowly linear, 

 yellowish but with a margin of one to several rows of hyaline, thin-walled, 

 rectangular to quadrate cells: capsule erect, exserted, with long, tapering neck, 

 symmetric, 8-plicate when dry, stomata superficial; annulus persisting; peri- 

 stome mostly double, segments usually 8, rarely 16 or none; lid convex or 

 conic, rostrate; calyptra mitrate, with 10-16 obtuse folds, incised-lobed at base, 

 hirsute with shining golden-yellow hairs or rarely almost glabrous. 



A world-wide genus of about 50 species, most numerous in America; in 

 North America about 15 species; in our region three species. 



