Jennings: Manual of Mosses — 2. Dicranaceae 45 



p)orted in our region, but to be expected, as it occurs in eastern Pennsylvania 

 and in Ohio, and its type locality is Harper's Ferry. 



Family 2. — DiCRANACEAE 



Autoicous or dioicous; large to minute, mostly cespitose: stem with a 

 central strand, often thickly covered with rhizoids, mostly densely leafy, 

 branched; leaves often falcate-secund, mostly acuminate to narrowly linear 

 from a broader base, usually more or less smooth and shining, usually costate; 

 costa sometimes dorsally serrate, heterogenous; leaf-cells sometimes mammil- 

 late, the basal ones enlarged and mostly transparent, alar cells often much 

 larger and either hyaline or brownish, the central leaf-cells short to rounded, 

 mostly smooth; perichstial leaves often sheathing: seta usually erect and long; 

 capsule mostly unsymmetric, usually cernuous, when dry often curved and 

 sulcate; annulus present or absent; peristome simply or rarely none; when 

 present the peristome teeth are 16 in number, approximate, united below into 

 a basal membrane, usually two parted to the middle, or beyond, into linear 

 or awl-like divisions, no longitudinal lines, but the teeth minutely striate or 

 papillose on the dorsal face, rarely smooth, inner face yellow with one or two 

 longitudinal lines and with more or less projecting trabecube, operculum more 

 or less long-rostrate; calyptra usually cucullate. 



Key to the Genera 



A. Capsule with a long, slender, usually curved neck; leaves suddenly lanceolate or 



subulate from a broad, clasping base 2. Trematodon 



A. Capsule neck, if any, much shorter than the urn B 



B. Cells of costa in cross-section homogeneous; peristome, if present, of 16 flat, 



smooth, usually entire teeth 6. Seligeria 



B. Cells of costa in cross-section heterogeneous; peristome none, or various C 



C. Alar cells not conspicuously enlarged or inflated D 



C. Alar cells conspicuously enlarged or inflated j 



D. Leaf-cells smooth or essentially so in our species E 



D. Leaf-cells more or less distinctly mamillose or papillose Q 



E. Leaves not crisped when dry F 



e. Leaves crisped when dry P 



F. Costa more than one-half width of leaf-base Brothera 



F. Costa less than half as wide as leaf-base G 



G. Cleistocarpous H 



G. With peristome I 



H. Capsule ovoid, immersed, short-apiculate 3. Pleundium 



H. Capsule pyriform with a short neck 1. Bruchia 



r. Peristome-teeth unequally subulately 2-3 cleft to the middle or somewhat below, 



papillose above 7. Dicranella 



I. Peristome-teeth cleft to the base or nearly so into two, linear, filiform papillose divi- 

 sions N 



J. Costa narrow, less than one-third as wide as leaf-base K 



J. Costa at least one-third as wide as leaf-base L 



K. Capsule mostly not strumose; peristome at base not forming a deeply inserted tube 



10. Dicratium 



K. Capsule strumose; jseristome teeth united at base into a deeply inserted tube 



9. Oncophorus 



L. No stereid bands in costa; costa filling most of the leaf above the middle M 



