THE RACEME AXD RELATED FORMS 



133 



FIG. 140. Raceme of 

 common red currant 



p, peduncle ; p', pedicel 



br, bract 



stem continues to grow the production of new leaves may be 

 followed by that of new flowers. Since there is no definite 

 limit to the number of flowers which may appear in this way, 

 the mode of flowering just de- 

 scribed (with many others of 

 the same general character) is 

 known as indeterminate inflo- 

 rescence. 



163. The raceme and re- 

 lated forms. If the leaves 

 along the stem were to become 



very much dwarfed and the flowers brought closer together, 

 as they frequently are, a kind of flower cluster like that of 

 the currant (Fig. 140) or the lily of the valley would result. 

 Such an inflorescence is called a raceme ; the main flower 

 stalk is known as the peduncle ; the little individual flower 



stalks are pedicels, and the small, 

 more or less scale-like leaves of 

 the peduncle are bracts. 



Frequently the lower pedicels 

 of a cluster on the general plan of 

 the raceme are longer than the 

 upper ones and make a somewhat 

 flat-topped cluster, like that of the 

 hawthorn, the elder, the sheep lau- 

 rel, or the trumpet creeper. This 

 is called a corymb. 



In many cases, for example the 

 parsnip, the sweet cicely, the gin- 

 seng, and the cherry, a group of pedicels of nearly equal 

 length spring from about the same point. This produces a 

 flower cluster called the umbel (Fig. 141). 



164. Sessile flowers and flower clusters. Often the pedicels 

 are wanting, or the flowers are sessile, and then a modification 

 of the raceme is produced which is called a spike, like that of 



FIG. 141. Simple umbel 

 of cherry 



