— 23 — 



Plants tree-like, with erect stems, and erect or spreading branches only 



towards the tip of the stem Climacium. 



Plants fern-like (branches bi- or tripinnate) 



Ptilium, Thiiidium, Hylocomium. 



Plants plume-like Ptilium. 



Color of stem. — The stems of most pleurocarpous mosses are either covered 

 with leaves and appear green, or are brown and inconspicuous. 



Stems and branches showing red through leaves, when moist plants are 



held to the light Climacium, Hypnum, Hylocomium. 



Position and shape of leaves. — The leaves of most pleurocarpous mosses 

 are erect or spreading, and are usually arranged equally around the stem and 

 branches, sometimes apparently in two rows. They are generally more or less 

 oval at the base, and end in a straight or curved tip, but are often too closely 

 folded or too small to show the entire outline. 



Leaves straight and flattened on opposite sides of the stem, apparently in 

 two rows, giving the plants a pressed appearance .... Neckera, Homalia, 

 Isopterygium, Plagiothecium, Brachythecium, Rhynchostegium. 

 Leaves curved and turned in two opposite directions, giving a braided ap- 

 pearance to the stems and branches • Stefeodon. 



Leaves strongly curved, and more or less turned in one direction 



Drepanocladus, Ctenidium, Ptilium, Stereodon. 

 Color of leaves. — The leaves of most mosses vary in color from a light 

 or yellowish green to dark green. 



Leaves usually light, yellowish or golden green. 



Capsule erect Dichelyma, Neckera, Entodon, Pylaisia. 



Capsule not erect Helodtum, Calliergon, Rhytidiadelphus, Hyp- 

 num, Ptilium, Cirriphyllum. 



Leaves usually very dark or olive green. 



Capsule almost concealed by the surrounding leaves Hedwigia. 



Capsule erect Fontinalis, Anomodon, Leskea. 



Capsule not erect Oxyrhynchium. 



Leaves glaucous or bluish green Thelia. 



Position of capsule. — The capsules of genera not mentioned are more or 

 less inclined. 



Capsule erect .... Fontinalis, Dichelyma, Climacium, Leucodon, Neckera, 

 Homalia, Entodon, Platygyrium, Pylaisia, Thelia, Myurella. 

 Capsule partially concealed by the leaves. .Hedwigia, Fontinalis, Leuco- 

 don, Neckera. 



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

 shaped, or short-beaked, and not especially conspicuous. 



Operculum conspicuously long-beaked Plagiothecium, Cirriphyllum, 



Oxyrhynchium, Eurhynchium, Rhynchostegium. 



Waban, Mass. 



