INFLORESCENCE 



159. Definition of inflorescence and flower cluster. The man- 

 ner in which flowers are arranged on the stem is known as 

 inflorescence. 1 Not infrequently the flowering shoot bears only 

 a single flower, but very generally among seed plants these 

 shoots are grouped into definite systems, which are called 

 flower clusters. 



160. Advantage of grouping flowers. Flowers when clus- 

 tered, as in Figs. 140-143, on special nearly leafless shoots are 

 much more conspicuous than they would be if scattered along 



ordinary leafy branches and partly hidden 

 by the leaves. This is a decided advantage 

 in securing many visits from insects which 

 carry pollen from plant to plant (Chapter 

 xxxn) and leads to a more abundant pro- 

 duction of seed. 



161. Regular positions for flower buds. 

 Flower buds, like leaf buds, occur regularly 

 either in the axils of leaves or at the end 

 of the stem or branch, and are therefore 

 either axillary or terminal (Sec. 168). 



162. Axillary and solitary flowers ; inde- 

 terminate inflorescence. The simplest pos- 

 sible arrangement for flowers which arise 

 from the axils of leaves is to have a single 



flower spring from each leaf axil. Fig. 139 shows how this 

 plan appears in a plant with opposite leaves. As long as the 



1 Sometimes (but less correctly) the word inflorescence is used to mean 

 flower cluster. 



132 



FIG. 139. Axillary 

 and solitary flowers 

 of pimpernel 



