BRISTLE MOSSES 



in 



Some of the top-fruiting mosses grow on trees. The curious 

 Four -Toothed Moss (Tetraphis), which grows chiefly on old 

 stumps and decaying wood, is well worth studying. It forms 

 bright green tufts, about an inch high, and many of the stems 

 end in a neat cup which 

 contains a number of 

 small buds or brood 

 bodies, each carried on 

 a short, slender stalk 

 (Fig. 23, D). On being 

 set free these bodies 

 produce new plants. 

 The fruits, which are 

 formed all summer, but 

 are often rather spar- 

 ingly produced, have a 

 peristome of four teeth, 

 which move inwards 

 and meet when moist 

 but stand erect when 

 dry(Fig.23,E,F). The 

 Bristle-Mosses (Ortho- 

 trichum) grow in neat 

 tufts on trees, and are 

 short, erect plants with 

 short-stalked capsules, 

 usually showing eight 

 ribs on the surface (one 

 kind has a smooth cap- 

 sule), and having a 



FIG. 25. Capsules of Bristle Mosses (Orthotrichum\ 



very elegant peristome. 

 In the commonest kinds 

 (Fig. 25, A, D) there are sixteen outer teeth, in eight pairs, which 

 when dry bend out widely and hang over the edge of the mouth, 

 and eight or sixteen slender inner teeth which behave in just 

 the opposite way, bending up when moist and closing down when 

 dry. Hence in damp weather the capsule mouth is closed, 

 while on drying the outer teeth bend right, but the spores can 



