1S6 



ELEMENTS OF BOTANY. 



The student should construct such' diagrams for some rather com- 

 plicated flower-clusters lilie those of the grape, horse-chestnut or buck- 

 eye, hardhaok, vervain, or many grasses. 



170. Terminal Flowers. Determinate Inflorescence. — The 

 terminal bud of a stem may be a flower-bud. In this case 

 the direct growth of the stem is stopped or determined by the 

 appearance of the flower, hence such plants are said to have 

 a determinate inflorescence. The simplest possible case of this 

 kind is that in which the stem bears but one flower at its 

 summit. 



171. The Cyme. — Very often 

 flowers appear from lateral (axil- 

 lary) buds, below the terminal 

 flower, and thus give rise to a 

 flower-cluster called a cyme. This 

 may have only three flowers, and 

 in that case would look very much 

 like a three-flowered umbel. But 

 in the raceme, corymb, and umbel 

 the order of flowering is from 

 below upward, or from the out- 

 side of the cluster inward, because 

 the lowest, or the outermost 

 flowers, are the oldest, while in 

 determinate forms of inflorescence 

 the central flowBr is the oldest, 

 and therefore the order of blossom- 

 ing is from the centre outwards. Cymes are very commonly 

 compound, like those of the elder and of many plants of 

 the pink family, such as the Sweet William and the mouse-ear 

 chickweed (Fig. 114). They may also, as already mentioned, 

 be panicled, thus making a cluster much like Fig. 113 A. 



t 



Fig. H4. — Compound Cyme of 



Mouse-Ear Chickweed. 



ij the terminal (oldest) flower. 



