HYPNACEAE 93 



Key 



i — Leaves with a distinct border joined with the costa at apex. . Sciaromium 



Leaves not bordered 2 



2 — Leaves blunt and rounded at apex Calliergon 



Leaves acute to acuminate 3 



3 — Leaf cells very long and narrow (except forms of D. aduncus); leaves 



mere or less falcate-secund Drepanocladus 



Leaf cells much shorter: leaves rarely falcate-secund (except Cra- 



toneuron) 4. 



4 — Paraphyllia abundant; plants plainly pinnately branched .. Cratoneuron 



Paraphyllia very few or lacking 5 



5 — Leaves widely spreading to squarrose-recurved (except polyganum) ; leaf 



cells usually more than six times as long as broad Campylium 



Leaves not squarrose-recurved; leaf cells usually less than six times 

 as long as broad Amblystegium 



AMBLYSTEGIUM B. & S. 



Mostly small moisture-loving mosses, growing on various 

 substrata; variously colored, dark green to yellowish, sometimes 

 blackish in the older portions, not glossy. Stems creeping, 

 branching freely and irregularly; central strand present, few- 

 celled. Leaves spreading to erect when dry, mostly equally 

 spreading, but occasionally somewhat secund, more or less 

 decurrent, lanceolate to ovate, acute to long-acuminate, strongly 

 costate, flat or concave, but not plicate, margins plane. Leaf 

 cells short, often less than 5: 1 (longer in A. vacillans and A. 

 riparium) ; basal cells shorter and broader and parenchymatous; 

 alar often somewhat enlarged, but not abruptly so, not inflated 

 or forming auricles except A. filicinum. Paraphyllia few or 

 more often wanting. Nearly always monoicous. Seta long, 

 smooth; capsules often large in comparison with the gametophyte, 

 inclined to horizontal, elongated and usually strongly curved 

 and constricted under the mouth when dry and empty; operculum 

 conical, not rostrate; annulus usually present; peristome per- 

 fect. The genus as here defined does not include the small 

 species having ecostate leaves. They belong in the Hypneae. 



The short leaf cells and long capsules, together with the 

 usually small size of the plants, render this genus fairly easy of 

 recognition, but the species, like most aquatic and subaquatic 

 mosses, are exceedingly variable and puzzling. 



