THE FLOWER. 



41 



inflorescence is determinate, because the length of the 

 axis is thereby determined ; it cannot grow longer. The 

 indeterminate inflorescence is also centripetal, that is, the 

 outermost flowers (when the cluster is level-topped), or the 

 lowest on the stem, open first, and those higher follow in 

 regular succession, until finally the one in the centre or at 

 the.top expands. Examples are furnished by the Lily of 

 the Valley, Currant, Plantain, Shepherd's-Purse, etc. The 

 determinate inflorescence is centrifugal, inasmuch as the 

 flowering begins inthe centre or top and proceeds outwards 



or downwards. This is exhibited in the Chick weed, Dian- 

 thus. Hydrangea, etc. 



49. The following are varieties of indeterminate inflores- 

 cence: Raceme, Corymb, Umbel, Spike, Spadix, Catkin, 

 Head, and Panicle. The raceme has the pedicellate 

 flowers scattered on an elongated axis (Fig. 88). The 

 corymb is the same as a raceme, with the lower pedicels 

 elongated so as to make the flower-cluster level-topped 

 (Fig. 89). In an umbel the axis is reduced, and all the 

 pedicels proceed from a common point (Fig. 90). The 



Figs. 88-91. Diagrams, illustrating forms of inflorescence : 88'. Raceme ; 89. 

 Corymb; 90. Umbel; 91. Spike. 



