CHAPTER XIY 



BRYOPHYTES (LIVERWORTS AND MOSSES) 



The Bryophyta are higher types of plants than the Thallophyta, 

 approaching more nearly to the conditions found in the higher 

 spore and seed plants in the structure of the plant body and in 

 the character of the reproductive organs. In the liverworts, or 

 Hepaticae, the plant body is termed a thallus, since they resemble 

 the thallop'hytes (algse and fungi) in not possessing true roots, 

 stems, and leaves. The mosses (musci) are more highly organized 

 than the liverworts and have stem and leaves resembling some- 

 what those of the higher plants, but this leafy-stemmed plant is 

 a gametophyte plant, as in the algse, instead of a sporophyte 

 plant, like the leafy plants of all plants above the bryophytes. 

 The liverworts and mosses, while differing in the form and 

 structure of the plant body, are nevertheless closely related by 

 the great similarity of their reproductive organs and the stages 

 of their life histories. 



HEPATICAE (LIVERWORTS) 



The simplest members of the Hepaticae are amphibious plants, 

 which occupy wet banks and overhanging rocks on the borders 

 of streams and lakes. They are named Hepaticae from their 

 fancied resemblance to the lobes of the human liver. As might 

 be expected, these simplest land plants exhibit transition stages 

 between the aquatic algae and the highest spore plants (repre- 

 sented by the mosses and ferns). The simplest forms are mere 

 ribbons of green cells, resembling in their structure the leaf of 

 Elodea or of a moss. They are attached to the mud or wet rocks 

 over which they grow by fine, hairlike roots called rhizoids, 

 which closely resemble the root hairs of the higher plants. 



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