INFLORESCENCE. 127 



cluster, having something the appearance of a compound 

 corymb, but easily distinguished by this peculiarity : that 

 the central blossom opens first, then those at the ends of 

 the first set of branches of the cluster, then those on the 

 secondary branches, and so on until the outer buds are 

 reached. The Elder, Dogwood, and St. John's Wort 

 furnish good examples of the cymose structure. Fig. 

 172 shows a loose, open cyme. 



Helicoid and Scorpioid cymes have already been 

 described in section 144. 



192. Besides the two distinct modes of inflorescence 

 just descril>ed, forms are met with which exhibit the 

 peculiarities of both modes. For example, the flower- 

 cluster of the Lilac is botryose or racemose as to the 

 production of its primary branches, but the development 

 of the flowers on the branches is according to the cymose 

 type. On the other hand it sometimes happens, in many 

 of the Composites for example, that the primary 

 branches are cymose while the secondary are botryose. 

 In the Lilac and the Horse-Chestnut the compact mixed 

 cluster is called a thyrse. Panicles, also, instead of being 

 altogether botryose, may be of a similar mixed character. 



193. In many plants of the Mint Family the flowers 

 appear to form dense whorls at intervals about the stem. 

 Each of these whorls, when analysed, is found to consist 

 of two cymose clusters on opposite sides of the stem. 

 Such whorls are, therefore, mixed, and are often spoken 

 of as verticillasters. 



194. It has already been pointed out that cauline 

 leaves tend to diminish in size towards the upper part 

 of the stem where the flowers are found. Such reduced 



