424 THE SAPINDALES 



wide distribution of these plants. It will be noticed in the 

 following orders as in the preceding Orchidales, that the irregu- 

 lar and more highly constructed flowers are generally represented 

 by a great number of genera and, barring some weakness, as for 

 example, the poorly developed embryos of the orchids and their 

 peculiar habitats, by a great number of individuals in each 

 species. 



145. Sapindales, the Soapberry Order. — This group includes 

 principally shrubs and trees, as the box, sumac (Rhus), smoke 

 tree (Cotiiuts), holly (Ilex), burning bush (Eiioiiyiiuts) , climb- 

 ing bittersweet (Cclastrus) , maple (Acer), horse-chestnut and 

 buckeye (Acsculiis), etc. The flowers are more commonly small, 

 of a yellow-green color and variously grouped into inflorescences 

 (Fig. 318, A). We noticed in the rose order as the dominant 

 characteristic the tendency towards the development of the basal 

 region of the receptacle which was associated with the checking 

 of its apical growth. In the Sapindales a similar shortening 

 of the axis without its basal growth leads to quite a different 

 series of variations. As a result of the crowding of the parts 

 of the flower upon the shortened receptacle, the distinguishing 

 features of the order are seen in the reduction of the number 

 of the organs of the flower, a tendency towards the cyclic arrange- 

 ment of parts and in the adhesion of the carpels. For example, 

 the sepals and petals are four to five in number, usually distinct 

 and the corolla may be entirely suppressed. There are two 

 whorls of stamens, five to eight in number, rarely ten, while 

 the pistils are reduced in number, ranging from two to more 

 commonly three or rarely five. Thus we see that the spiral 

 type of flower so often noticed in the rose and preceding orders 

 has become reduced as a rule to the cyclic type and that five 

 numerous sets of organs are not of common occurrence. This 

 reduction of the flower and the suppression of parts is well 

 illustrated in the maples (Fig. 318). The sepals cohere, forming 

 a five-lobed calyx. The petals are often suppressed and a 

 nectar disc is developed outside the stamens, a distinguishing 

 feature of the order (Fig. 318, C). The two whorls of stamens 

 are suppressed to a varying degree so that from four to eight 



