Leafy Mosses 



by the wind, will grow into new plants, 

 if they fall in favourable places. 



HOW THE SPORES ESCAPE FROM 

 THE SPORE-CASE 



When the weather is damp, although 

 the spores are ripe, the teeth of the Poly- 

 trichum mosses hold the membranous 

 disk so that the spores cannot escape. 

 When the weather is dry the teeth are so 

 modified as to make a ring of holes be- 

 tween the teeth and the edge of the disk, 

 through which the spores may pass. 



There are mosses with their teeth trian- 

 gular in shape. These have the bases of the 

 triangles fastened at the rim and the points 



Teeth. 



Tetraplodon mnioides. 

 Spore-case with eight 

 pairs of teeth turned 

 back. 



Leucobryum vulgare. Portion 

 of single peristome showing 

 four teeth split half way to the 

 base. 



Polylrichum juni- 

 perinum. An o 1 d 

 sporophyte with 

 lid removed. 



Georgia pellucida. 

 Top of spore -case 

 with four teeth. 



meeting at the centre. In some species the teeth simply arch up, 

 remaining fastened at the points, and let the pores escape, wh 

 in other species they turn back like 

 the ray flowers of a daisy. 



Some species have at the base 

 of the teeth a single or double row 

 of short bead-like cells (annulus) 

 which swell up at the proper time 

 to push off the spore-case lid. 



37 



Teefh 



Funaria hygrometrica. Summit or 

 spore-case. 



