110 



MANUAL OF BOTANY 



Fig. 200 



the summit of the cone or in the centre of the flattened portion. 

 The youngest flowers consequently appear in that position and 

 the oldest ones are at its periphery. The order of expansion is 

 in these cases said to be centripetal. 



A number of flowers being thus developed upon an elongated, 

 shortened, or dilated peduncle, several varieties of this kind 

 of inflorescence exist, depending upon the extent to which the 

 floral axis branches, the comparative 

 lengths of the flower-stalks, or their 

 complete suppression, and other sub- 

 ordinate circumstances. The chief 

 forms may be described under three 

 heads : first, those which have an elon- 

 gated primary axis ; second, those in 

 which the primary axis is shortened ; 

 third, those in which it becomes dilated 

 and fleshy. The first two maybe fm-ther 

 subdivided into simple and compound 

 types, the former including those in 

 which the main axis produces flowers 

 only, the latter those in which it de- 

 velops secondary peduncles on which 

 several flowers arise. 



A. Forms possessing an Elongated 

 Primary Axis. 



Fig. 209. Raceme of a species 

 of Chen-y (Pfunus I'lirh/s). 



The simple forms of this class in- 

 clude the Eaceme and the Spike, 

 with their varieties. 



a. The Raceme. — This is the simplest inflorescence of the 

 indefinite type, and from it the name racemose is derived. The 

 elongated peduncle bears a number of flowers in acropetal suc- 

 cession, each being furnished with a pedicel. When fully formed 

 the pedicels are nearly of equal length. Examples of it occur 

 in the Currant, Mignonette, Hyacinth, Laburnum, Barberry, 

 Fumitory, &e. Such a form is seen in fig. 209, the raceme of a 

 species of Prunus. It will be noticed that the flowers at the 

 lower part of the peduncle are fully expanded, while those at 

 the apex are still in the condition of buds. The acropetal order 

 of expansion is therefore easily observable. 



b. The Corymb. — This is a variety of the raceme, in which 

 the pedicels, instead of being of nearly equal length un the 



