DEVELOPMENT OF PLANTS 



257 



of the mucilage secreted by glandular hairs growing among them 

 (Fig. 189). These minute bodies grow directly into new plants 

 and so serve to rapidly multiply the plant. 



The reproductive organs appear upon different plants which 

 may therefore be distinguished as antheridial or male plants and 

 archegonial as female plants (Figs. 186, 190). Such a distribu- 



FIG. 190. Thallus of Marchantia bearing several erect branches with 

 lobed or umbrella-like tops. The archegonia are situated on the underside 

 of the umbrella, between the lobes, a, the early appearance of a branch, 

 in which condition fertilization is effected. 



tion of the sexual organs is termed dioecious, meaning in two 

 households, whereas Ricciocarpus and others are said to be mon- 

 oecious, because the exual organs are developed upon the same 

 plant. The antheridia and archegonia are developed, as in Ric- 

 ciocarpus, upon the upper surface of the thallus, but they are 

 confined to special portions of it which appear at first as mush- 

 room-shaped outgrowths (Fig. 190, a). These outgrowths, 

 however, are but modified branches of the thallus and bear the 

 sexual organs upon their upper surfaces in lines radiating from 

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