296 A MANUAL OF MOSSES 



squarrose, sometimes circinate-secund, mostly plicate, scarcely 

 decurrent, from an ovate or cordate base more or less long- 

 acuminate, plane-margined, rather sharply serrate ; costa short, 

 double, or sometimes none ; cells narrowly linear, smooth, or 

 the upper angle projecting dorsally as a tooth, the basal wider, 

 shorter, more or less incrassate and porose, colored, the alar 

 mostly not differentiated; seta 2-4 cm. long, castaneous; cap- 

 sule horizontal to pendent, from a very short neck thickly oval, 

 dorsally gibbous, when dry and empty plicate, but not con- 

 stricted below the mouth, annulate; peristome normally 

 hypnoid ; lid convex, conic-acute. 



A genus of 5 species of forest and meadow in the tem- 

 perate and cold regions of the Northern Hemisphere ; 4 species 

 in North America; 2 species in our region. 



Key to the Species. 

 a. Cells smooth both sides; stem-leaves not plicate, sqtiarrose-re- 



curved. 1. R. squarrosus. 



a Cells dorsally spinose: stem-leaves strongly plicate, spreading. 



2. R. triquetrns. 



1. Rhytidiadelphus squarrosus [Linnaeus] Warnstorf. 



(Hypnitin squarrosii/ii Limuetis ; Hylocomium sqitarrosinn Bryo- 



logia Europaea). 



Widely and softly cespitose, bright green, lustrous : stems 

 robust, but slender, up to 10 or even 15 cm. long, procumbent 

 or more or less ascending to erect at the ends, the branchlets 

 rather distant, fiexuous, unequal, attenuated and more or less 

 sub-flagelliform ; stem-leaves crowded, about 3 mm. long, 

 abruptly squarrose from a cordate-ovate more or less erect- 

 sheathing base, not secund, imbricated, the squarrose portion 

 long and gradually tapering and channeled, denticulate above, 

 the apical leaves somewhat stellately spreading, branch-leaves 

 smaller but otherwise very similar to stem-leaves ; costa short, 

 double, faint; median leaf-cells smooth dorsally, about 8-10;l, 

 narrowly-linear, the alar gradually rectangular-hexagonal, 

 larger, short, opaque to pellucid, numerous, but. not forming- 

 abruptly differentiated auricles ; perichsetial leaves squarrose, 

 the inner linear-acuminate and apically serrate : seta usually 

 3-4 cm. long, fiexuous ; capsule short, ovoid, dorsally gibbous, 

 inclined to horizontal, or even pendent by the curving of the 

 upper part of the seta ; lid convex-conic, rather acute ; annulus 

 2-seriate ; peristome normally hypnoid, segments carinately 

 split between the articulations, cilia 3; spores mature in winter 

 or early spring. 



In moist or wet meadows and borders of woods in grassy 

 places ; Azores, Europe, Asia, and, in North America, from the 

 Arctic regions to the northern United States. Rare in our 



region. 



Cambria ; Lesquereux, at Cresson. (Porters Flora). 



