02 



A TEXTBOOK OF THEORETICAL BOTANY 



coasts. The thallus consists of a single coenocyte, but this enormous cell 

 shows differentiation into a main axis, from which arise, towards the upper 



Fig. 72. — Various species of Caiderpa illustrating the remarkable degree of difTer- 

 entiation which can be achieved by a coenocytic structure. A, C. ligiilata. 

 B, C clavifera. C, C. prolifera. D, C. sertularioides. 



end, two rows of lateral branches or pinnae (Fig. 73). From the lower end 

 of the axis there is formed a little-branched horizontal rhizome anchored by 

 rhizoids. This rhizome may produce numerous upright axes, so that each 

 plant actually consists of a little tuft of vertically growing filaments. The 

 pinnae vary in length, those nearest the base being the longest and decreasing 

 regularly towards the apex. Each pinna is an elongated sac, and there is a 

 constriction at the base w^here it joins the main axis (Fig. 74). No true 

 septa are formed in the coenocyte prior to the reproductive phase and the 



