CHAPTER XI.- — THE BRYOPHYTA. 335 



CHAPTER XI. 



SERIES II.— THE BRYOPHYTA, OR MOSS PLANTS. 

 The Hepatioe — The Musci. 



I. Hepaticae -j 



[ Riccieae. 



I Anthoceroteae. 



Marchantiaceae. 

 L Jungermanniaceae. 



Sphagnaceae. 



II. Musci 



Andreaceae. , , 



l Acrocarpi. 



Bryaceae < Cladocarpi. 



( Pleurocarpi. 



The plants of this Series, on the whole, show, in the more 

 complete differentiation of their cells into tissues and of the 

 plant body into stem, leaves and root-hairs, as well as in their 

 more complicated reproductive process, a decided advance in 

 structure over the members of the preceding Series. At first 

 sight the two groups seem sharply distinct, but a closer com- 

 parison shows that there are few points in the Bryophyta which 

 have not been clearly anticipated by some of the plants below 

 them. In turn, the Bryophyta anticipate some of the features of 

 the higher plants. 



All Moss-plants are chlorophyll-bearing ; in all, the plant 

 body consists of true tissues formed by cell-division ; all are of 

 small or moderate size, seldom attaining more than a few inches 

 in height, yet none of them at maturity are so small as to be 

 strictly microscopic ; none possess true roots, though many bear 

 root-hairs, corresponding probably to those of the higher plants, 

 by means of which they attach themselves to the substratum or 

 absorb nutriment ; a few are aquatic ; most are either terrestrial 

 or epiphytic, but none are either parasitic or saprophytic. 



All the species are characterized by a distinctly-marked 

 alternation of a sexual with an asexual generation. The plant 

 which bears the sexual organs is the more conspicuous ; it may 

 be either a leafy-stemmed plant or a thallus. It does not spring 

 directly from a spore, but the latter, in germinating, first forms a 



