TUE FLOWER 



115 



223. Union of unlike parts, or adnation. — Fi-equeiilly (he stiniiens 

 seem to grow from the corolla, because the filameiits have grown 

 to the petals (Figs. 160, 161). Again, in the flower of Cuphea, for 

 example, calyx, corolla, and stamens adhere in a cup around the pistil, 



160. Flower iif a Primrose laid open; 

 cu, corolla; ca, calj^v. 



Idl. Flower ol' Cuphea laid open: 

 cty calyx tube; j't^ petals. 



in such a manner that both stamens and petals seem to be inserted on 

 the margin of tlie calyx tube (Fig. 101). Finally, in the Pmslane 

 (Fig. 162) all tlie different members are miited, witli tlie o\iL.ry in the 

 center. The ovary is in such cases said to be inferior. AVlieu free 

 from the organs, it is superior (Fig. 160). Tlie adherence of unlike 

 members is termed adnation. In the Purslane, for example, the calyx 

 is said to be ailnate to the ovary. 



Coalescence and adnation come about in the following manner. 

 The rudiments of the carpels, stamens, petals, and sepals appear at 

 first as minute elevations on the young receptacle. As these increase 

 the surface of the receptacle between them may be involved in the 

 growth. Thus, if tlie tissue between 

 the nascent jielals is affected, a cir- 

 cular ridge arises, upon the edge of 

 which the po.sition of the original 

 petal rudiments is indicated by prom- 

 inences. Tbe ridge, or ring, grows up 

 into a longer or shorter tube (the 

 corolla tube), the original prominences 

 becoming lol)es or divisions. By a 

 similar process, in the Primrose (Fi 

 stamens lieconie united to the corolla ring at an early stage. In 

 the Purslane (Fig. 162) a single ring arising from the receptacle, 

 and bearing all the floral organs on its summit, comes to form the 

 so-called " calyx tube." 



1G2. Flower of the Purslane. 

 160) the rudiments of the 



