— 22 — 



Midrib seen when moist plants are held to the light. 



Rhodohryum, Mnium, Catharinaea. 

 Color of leaves. — The color of the leaves of most mosses varies from light or 

 yellowish green to dark green. 



Leaves usually conspicuously light or yellowish green 



Physcomitrium, Funaria, Aulacomnium, Philonotis, (Sphagnum). 



Leaves glaucous or whitish green, especially when dry 



Leucohryum, (Sphagnum). 



Leaves bluish green Saelania, Polytrichum. 



Leaves usually conspicuously dark or olive green .... Grimmia, Rhacomi- 

 trium, Drummondia, Orthotrichum, Bryum, Webera, Georgia. 



Leaves sometimes with a reddish tinge Catharinaea, (Sphagnum). 



•Seta. — The seta of most mosses is single, reddish brown, and conspicuous. 



Seta yellowish Trematodon, Ditrichum, Dicranella. 



Physcomitrium, Dicranum, Funaria. 



Seta dark red Ceratodon, Pohlia. 



Setae clustered Dicranum, Rhodobryum, Mnium, Catharinaea. 



Seta very short, apparently absent, so that the capsule is partially concealed 



by the surrounding leaves. Grimmia, Orthotrichum, Webera. 



Position of Capsule — 



Capsule erect. .. .Ditrichum, Dicranella, Dicranum, Fissidens, Rhacomi- 

 trium, Orthotrichum, Ulota, Physcomitrium, Georgia, 

 Catharinaea, Pogonatum, Polytrichum' 

 CapsnXe inclined ... .Trematodon, Ditrichum, Ceratodon, Dicranella, Di- 

 cranum, Leucobryum, Aulacomnium, Bartramia, Phil- 

 onotis, Catharinaea, Polytrichum. 

 Capsule horizontal. . . . Pohlia, Bryum, Rhodobryum, Mnium, Polytrichum. 



Capsule hanging down Funaria, Leptobryum, Pohlia, Bryum, 



Rhodobryum, Mnium, Polytrichum. 

 Capsule partly concealed by surrounding leaves . . . Grimmia, Orthotrichum. 

 Shape of operculum. — The operculum of most mosses is convex, cone-shaped, 

 or short beaked, and not especially conspicuous. 

 Operculum conspicuously long beaked ... .Trematodon, Ditrichum, Di- 

 cranella, Dicranum, Leucobryum, Catharinaea, Polytrichum. 

 Calyptra. — The calyptra of most mosses is smooth and inconspicuous, often 

 falling off long before the capsule is mature. 



Calyptra hairy and conspicuous Orthotrichum, Ulota, Pogonatum, 



Polytrichum. 



IL' Pleurocarpcus Mosses. 



Manner of growth. Pleurocarpous mosses usually grow in rather flat mats 

 with the stems and branches prostrate or creeping, and often closely 

 interwoven so that .no great length of stem can easily be separated. 



Plants with stems usually ascending or erect and easily separated 



Climacium, Helodium, Drepanocladus, Calliergon, Rhytidiadelphus , Hy- 



locomium, Hypnum, Ptilium, Stereodon. 



