38 



STRUCTURAL AND PHYSIOLOGICAL BOTANY. 



300. When a single flower-bud unfolds in the axil of a leaf, 

 and the general axis continues to lengthen, and the leaf under- 

 goes no sensible diminution of size, the flower which is deve- 

 loped is said to be solitary and axillary. 



301. If all the buds of a newly formed elongated branch 

 develope as flower-buds, and at the same time produce pe- 

 duncles, a raceme is formed 163 . 



302. If buds, under the same circumstances, develope with- 

 out forming peduncles, a spike is produced 1 . 



303. Hence the only difference between a spike and raceme 

 is, that in the former the flowers are sessile, and in the latter 

 stalked. 



304. A spadix differs from a spike in nothing more than in 

 the flowers being packed close together upon a succulent axis, 

 which is enveloped in aspathe (277). 



305. An amentum is a spike the bracts of which are all of 

 equal size, and closely imbricated, and which is articulated 

 with the stem. 



306. When a bud produces flower-buds, with little elonga- 

 tion of its own axis, either a capitulum 170 172 , or an umbel 16 ', is 

 produced. 



307. The capitulum bears the same relation to the umbel 

 as the spike to the raceme ; that is to say, these two forms 

 differ in the flower-buds of the capitulum being sessile, and of 

 the umbel having pedicels. 



