48 



PART I. — ORGANOGRAPHY. 



common mode of branching in Marine Algae, the leaves of some 

 Ferns and in the stems and roots of Club-Mosses. 



In the monopodial type the branches originate as lateral out- 

 growths, back of the apex of the main stem, as illustrated in Fig. 

 172. There are also several modifications of this type : 



(1) The Racemose Monopodium, in which the main axis 

 retains the ascendancy over its branches, as in Fig. 172. 



(2) The Cymose Monopodium, in which the main axis is 

 soon suppressed and the lateral branches gain the ascend- 

 ancy. Of the latter 



kind there are several S\f"$jLj^ hJt 



variations 



(a) The False Dich- 



otomy, represented in tf^f \^/y 

 Fig. 173, in which the "**" 



* 



Fig. 171. 



lateral branches de- 

 velop in such a manner 

 as to resemble true 

 forks, or a genuine 

 dichotomy. 



(b) The Helicoui 

 Monopodium, in which the main axis and lateral branches on one 

 side are habitually suppressed, while the branches on the other 

 side are developed to form a false axis, as in Fig. 174. 



-Diagram of forked dichotomy. 

 -Diagram of helicoid dichotomy. 

 -Diagram of scorpioid dichotomy. 



X 



q 



V 



V 



Fig. 172. 



Fig. 173. 



Fig. 174. 



Fig. 175. 



Fig. 172. — Diagram of a racemose monopodium. 

 Fig. 173. — Diagram of false dichotomy. 

 Fig. 174. — Diagram of the helicoid monopodium. 

 Fig. 175. — Diagram of the scorpioid monopodium. 



(c) The Scorpioid Monopodium, in which the main axis soon 

 ceases to grow and the branches are suppressed alternately on 

 one side and then on the other, as illustrated in Fig. 175. 



