GROUP II. BRYOPHYTA. 



325 



differentiated into stem and leaf, as in the higher Hepaticse 

 (foliose Jungermanniacese) and in the Musci. 



The sexual organs are borne on the adult shoot, and are an- 

 theridia and archegonia. They are rarely borne singly or scat- 

 tered, but more commonly in groups (sori) surrounded by some 

 kind of protective investment to which the general term involucre 

 may be applied. In some cases the portion of the shoot which 

 immediately bears the sexual organs is more or less specialised as 

 a receptacle, and in others special reproductive branches, gameto- 

 phores, are differentiated, and may be either antheridiophores or 

 archegoniophores. In the lower Hepaticae the sexual organs are 

 generally borne on the upper (dorsal) surface of the shoot, whilst 



FIG. 232. Fmiaria hygrometrica (Moss). A Germinating spores: tc rhizoid; s exospore. 

 B Part of a protonema, about three weeks after the germination of the spore : 7i a pro- 

 cumbent primary shoot with brown wall and oblique septa, out of which arise the 

 ascending branches with limited growth : K rudiment of a leaf-bearing axis with rhizoid 

 (w). (A x 550: B about 90.) 



in the higher Hepaticae (Jungermanniaceaa acrogynee) and in the 

 Mosses they are borne at the apex. 



The distribution of the sexual organs is various : the male and 

 female organs may be borne on distinct shoots, when they are 

 dioecious ; or on different branches of the same shoot, when they 

 are monoecious but diclinous ; or together in the same sorus, when 

 they are monoclinous. In Mosses it appears to be the rule, in 

 dioecious forms, that a protonema always bears both male and 

 female shoots. 



