

Ill] MONOPODIAL GROWTH 39 



If the parent-axis maintains its rate of elongation, 

 and the lateral axes, in acropetal succession, go on grow- 

 ing uniformly, or nearly so, it is clear that the whole 

 shoot-system consists of one primary axis and its ap- 

 pendages, and has a more or less conical or pyramidal out- 

 line according to the angular divergence and directions of 

 growth of the laterals e.g. young Pines, Firs, &c. already 

 referred to (Fig. 1). 



Nor is the matter essentially altered if the primary 

 axis grows less rapidly than the laterals, and these come 

 to over-top it in time, though in this case the whole out- 

 line of the shoot-system is altered. 



The fundamental fact here concerned is that there is 

 only one primary axis, which, continuing its onward growth, 

 throws off secondary lateral axes which grow out at 

 various angles from it. This on-growing primary axis 

 is often termed a Monopodium, and the total branch- 

 system thus developed is frequently termed Racemose or 

 Indefinite the latter term referring to the continued on- 

 growtfa of the primary axis. Of course no difference in 

 principle is introduced when the secondary axes bear 

 tertiary ones, and behave similarly, and so on with higher 

 orders of branching, as is well seen in many Conifers 

 during the first twenty or thirty years of growth, during 

 which the regular pyramidal-conic form is maintained, 

 each lateral branch growing proportionally equally as the 

 leader elongates. 



An essentially different system of branching is met 

 with, however, if the primary axis stops growing by the 

 death of its vegetative apex, while the secondary axes 

 continue their onward growth, and many of the most 

 interesting and difficult forms of branch-systems are due 

 to this phenomenon. 



A simple case is afforded by the branches of a Lime or 



