DIV. I 



MORPHOLOGY 



127 



II. The main axis grows as strongly as the lateral axes. 



4. UMBEL : a whorl of lateral axes bearing flowers on a main axis which 



grows to the same length and ends in a flower (Fig. 150 C, Fig. 148). 



5. COMPOUND UMBEL : an umbel which has small umbels in place of the 



single flowers (Fig. 150 F). 



6. CAPITULUM or HEAD : flowers sessile on a shortened main axis (Fig. 



150 Z>). 



(b) The term eymose branching is applied when the main axis 

 grows LESS STRONGLY than the lateral axes, which continue the 

 branching and in their turn are overtopped 

 by the branches they bear. The resulting 

 appearance differs according to whether 

 several, equally strong, lateral axes of the 

 same order, or only* one lateral 

 axis, continue the branch-system. 

 In the latter case an apparent 

 main axis or SYMPODIUM is 

 formed. 



In many cases of eymose branching 

 the parent axis not merely grows more 

 slowly than the daughter axes but its 

 tip dies or is cast off. This happens 

 in many of our trees such as the Willow 

 or the Lime. 



FIG. 148. Umbel of the Cherry. 

 (After DUCHARTRE.) 



FIG. 149. Panicle of Yucca filamentusa. 

 (After A. F. W. SCHIMPER. Reduced.) 



I. If more than two lateral branches of the same order continue the branching 

 the term PLEIOCHASIUM is used. Such lateral branches are usually approximated 

 to the upper end of the parent axis and radiate on all sides obliquely upwards, in 

 some cases being arranged in a whorl. The inflorescence of Euphorbia affords an 

 example. 



II. If two lateral branches of the same order continue the branching and stand 

 opposite to one another, forming an acute or right angle, the term DICHASIUM is 

 used. This is shown diagrammatically in ;Fig. 151, with which the dichasial 

 inflorescence in Fig. 153 may be compared. A branch system of this kind, another 

 example of which is afforded by the Mistletoe, which grows parasitically on trees, 

 simulates a dichotomy. The successive pairs of lateral branches do not lie in one 



