OF THE OIIGAXS. G5 



Still less common is the ringent, which, however, lias been ol>- 

 served in one whole family in South America. 



98. 



In the Polypetalous corolla, we also attend, for the purpose 

 of defining its shajx", to its resemblance to some generally 

 known ibrni. We thus say that a corolla is rose-bhaped, 

 j)ink-shape(l, or lily-shaped {corolla rosea, caryophyllacca^ 

 i'diacea). 



To this class belongs also tlie Papilionaceous corolla {co- 

 rolla papU'tonacca). It consists of four parts, the upper ex- 

 panded part, or tlie standard {veaclllum) ; the two lateral 

 parts or the zvlngs (cda), and the lower boat-shaped part, or 

 the keel {carina). These four parts consist sometimes of but 

 one piece, as in clover. In other cases, the keel consists of 

 two parts, or it is entirely wanting, as in Tamarind us, and 

 Amorpha. In many of these papilionaceous flowers, as in 

 Plymena^a, a more perfect resemblance between the parts of 

 the corolla takes place, and they a]:)proach, by this means, to 

 the regular form. 



99. 



We must attend to the situation and folding of the flower 

 before its evolution. These are called Estivation. It is witli 

 respect to flowers, what the interior structure of the leaf-buds 

 is to the leaves. We observe, 



1. An testivatio valvaris, when the parts of the corolla, 

 before evolution, only touch one another with their margins, 

 like the valves of the capsule. We observe this, for instance, 

 in compound flowers. 



2. The astivatio contorta. Here the parts of the corolla 

 stand so obliquely, that they cover the margins of each other. 

 This estivation is remarked principally in the family of the 

 Contortas, which hence derive their name, because, even after 

 their complete evolution, they still retain the oblique position 

 of the parts of the corolla, as may be seen in Vinca, Xerium, 

 and Arduina. We also observe this estivation in Pinks. 



E 



