84 HYPNACEAE 



loosely spreading, erect-open when moist. Very rarely falcate 

 or secund except in B. velutinum and its allies, often strongly 

 plicate or sulcate, at least when dry, simply costate half way or 

 more, leaf-cells linear-vermicular (except B. reflexnm, B. digas- 

 trum and B. cyrtophyllum) . Alar cells differentiated, often 

 inflated and hyaline, sometimes quadrate and densely chloro- 

 phyllose. 



Capsules brown to chestnut-brown, ovoid, short, cernuous 

 and unsymmetric except in Homalotheciella and in B. oxycladon, 

 and B. acuminatum and its allies, rarely or never plicate or 

 strongly contracted under the mouth when dry; operculum conic, 

 conic-apiculate or long-rostrate, seta often roughened with 

 prominent papillae; peristome perfect except in species hav- 

 ing erect capsules. 



Key to the Genera 



i — Operculum with very long, needle-like beak 2 



Operculum conic or at most with a very short beak 3 



2 — Apices of branch leaves abruptly long-acuminate from a spoon-shaped 



base, apical cells not broader or shorter than the median. Cirriphyllum 

 Apices of branch leaves acute to obtusely-acute, with apical cells 

 broader and shorter than the median (except E. semdattim) . 



Eurhynchium 

 3 — Leaves markedly papillose on the back with projections from the 



angles of the cell walls; seta rough Bryhnia 



Leaves not papillose, seta rough or smooth 4 



4 — Leaves all elongated-lanceolate, very strongly sulcate with numer- 

 ous folds; plants very glossy, golden green Camptothecium 



Leaves broader, less strongly sulcate or even smooth, less glossy 5 



5 — Calyptra smooth; inner peristome free Brachythecium 



Calyptra hairy; inner peristome adherent to teeth Homalotheciella 



BRACHYTHECIUM 



Plants mostly of medium size and typically hypnaceous 

 habit, very rarely pinnately branching with any degree of regu- 

 larity. Branch leaves acute to acuminate, never obtuse, usually 

 somewhat concave and often plicate or sulcate, costate to above 

 the middle, median leaf cells sinuous-linear to linear-rhomboidal 

 (broader and shorter in B. reflexum, B. digastrum and in some 

 leaves of B. cyrtophyllum) , basal cells broader and shorter, alar 

 quadrate, rarely inflated and hyaline. 



