Branch Systems 



67 



always on the same side, a helicoid or bostrychoid dichotomy 

 is formed (fig. 99, b). If the stronger bifurcation alternates, 

 first to the right and then to the left, we have a scorpioid or 

 cicinnal dichotomy (fig. 99, c). 



2. If the axis is prolonged beyond the branch, a monopodial 

 branching is produced. If the main axis continues to develop 

 more strongly than the branches, the branching is said to be 

 racemose ; in other cases the main axis soon ceases to grow, 

 and the shoots become strong ; the branching is now said to be 

 cymose. 



There are two varieties of this : — 



a. When two or more shoots arise near the apex of the 

 podium and develop more strongly than the main axis, which 

 soon ceases to grow. This is called false dichotomy (or if 

 three branches, trichotomy, or if more than three, polytomy) 

 (fig. 100, c). 



4 



3 



■S Q 



/ ^ 



.1 



Fig. too,— Diagrams of sympodial varieties of monopodial branching. A and i>, 

 cicinnal monopodia. C dicha.-ium, or false dichotomy. D, bostrychoid monopodium. 

 The axes are numbered in succession from i to 7. (After Sachs.) 



b. When only one shoot grows it forms a pseud-axis or 

 sympodium, which may form a scorpioid or cicinnal cyme if 

 the branches come off on opposite sides (fig. loo, a, b), or a 

 helicoid cyme if they all, come off on the same side (fig. loo, d). 



