184 



BOTANT. 



an upper and an under one, the latter bearing the root- 

 hairs (rhizoids), by means of which the plant is fixed to 

 the ground. In this class breathing-pores are found for 

 the first time in the vegetable kingdom. They are of very 

 simple structure (Fig. 101). 



386. The leaves, when present, are usually in two rows 

 (sometimes three), and are either opposite or alternate. 

 The tissues of the plant-body show a little differentiation; 



Fi». 101.— I, a thalloid LiTerwort; Band C, showing bud-cups, natural size; D, 

 enlarged to show breathing-pores. i7, a leafy -stemmed laverwort; a, unnpe, 

 and 6, ripened and split, spore-fruit. 



the leaves, however, have no midrib or other veins, and 

 consist of a single layer of cells. The development of the 

 stem is always from a single apical cell, which repeatedly 

 divides. 



387. The asexual reproduction of Liverworts takes place 

 by means of peculiar bodies, the bads (or gemmae) so fre- 

 quently to be seen in the Common Liverwort (Marchantia 

 polymorpha). In the latter plant they are little stalked 



