274 American Midland Naturalist Monograph No. 6 



at the main forks and usually quite difficult to separate from the substratum 

 without breaking in pieces; leaves about 1.5 mm long, complanately arranged, 

 lance-ovate, long-acuminate from an ovate-oblong base, sharply serrate above 

 the middle, margins plane, serrulate, or entire towards the base; costa none 

 or very short and faint; oerichaetial leaves ovate, basally concave, abruptly 

 short-pointed, dentate at apex; median leaf-cells fusiform to broadly linear, 

 prosenchymatous, about 8-12:1, the basal a little shorter and wider, the alar 

 either not differentiated or a few sub-quadrate to rectangular and incrassate: 

 seta slender, about 1.5 cm long, castaneous, somewhat twisted; capsule oblong, 

 about 2-3.1, about 2 mm long, slightly curved and somewhat inclined when 

 young, when old and empty arcuate, horizontal, plicate, castaneous, and con- 

 stricted below the mouth; annulus large, double; lid conic; exothecial cells 

 small and rounded in three or four series at the rim, gradually becoming 

 oblong-rectangular or irregular-oblong below, the upper more or less distinctly 

 rastaneous-collenchymatous; peristome small, the teeth lance-subulate, papil- 

 lose above, dorsally transversely striolate below, strongly trabeculate and 

 lamellate, slightly confluent at base; segm.ents nearly as long, narrow, not split, 

 papillose, yellowish, basal membrane about two-fifths as high; cilia strong, 

 nodose, often about as long as the segments, 1 or 2 in number; spores more 

 or less greenish-yellow, about .008-.011 mm, papillose, rather thin-walled, 

 mature in summer. 



On rich woods-humus in moist woods or in peat bogs; Europe, and from 

 Canada to Georgia and Texas. 



Cambria Co.: Ebensburg. T. P. James. (Porter's Catalogue). Crawford Co.: 

 In swamp near Hartstown, May 29-31, 1909. O.E.J, and G.K.J, (figured). McKean 

 Co.: East. Branch Swamp, Bradford, July 1, 1896. D.A.B. 



21. Plagiothecium Bryologia Europaea* 



Autoicous or dioicous, rarely polyoicous: usually more or less robust, most- 

 ly softly cespitose, bright to yellowish or whitish-green, lustrous: stems creep- 

 ing to ascending, or in thick cushions erect, with ascending and small-leaved 

 stolons, mostly irregularly branched; branches often elongate-flagelliform; 

 paraphyllia none; leaves uniform, obliquely inserted, non-plicate, some species 

 complanate-distichous, concave from a narrow and more or less decurrent base, 

 broadly lanceolate to ovate, acuminate, mostly plane-margined and entire, 

 sometimes serrate; costa short, mostly double, sometimes none; median leaf- 

 cells chlorophyllose, elongate-rhom.boid to linear, thin-walled, the basal shorter 

 and wider, the alar lax and hyaline: seta long, reddish, drying twisted; capsule 

 erect to cernuous, with collum, oblong to cylindric, symmetric to weakly dor- 

 sally gibbous, drying wrinkled or smooth and often arcuate; annulus mostly 

 revoluble; peristome-teeth yellowish, confluent basally, lance-subulate, mostly 



* Plagiothecium and the next following genus (Isopterygium) are probably best treated 

 as one genus. Grout (Moss Flora, 1932) unites them under Plagiothecium. Brotherus 

 (Die Naturlichen Pflanzenfamilien. 2nd edit. 1925) recognizes Plagiothecium and Isopter- 

 ygium as here treated except that he places deplanatum and geophilum in a third genus 

 Taxiphyllum. 



