GYNANDRIA. 193 



of food, and at the present day is grown in some parts of the 

 world, as a substitute for that root. 



The genus Coreopsis, and the very extensive one, Cen- 

 taurea, (Ccntaury,) belong here. The latter contains some 

 handsome garden flowers, and one or two medicinal plants. 

 ORDER IV. SYNGENESIA NECESSARIA. 



In this order the florets of the disk are furnished with 

 stamens, but have no pistils, while those of the ray have 

 pistils, but no stamens ; hence the name Necessaria, because 

 to perfect the seed, these two organs, the stamens and pis- 

 tils, are necessary to each other. This order is nearly bar- 

 ren of interesting species. The most conspicuous genera 

 are the Marygold, (Calendula,) the Ragwort, (Othonna,) and 

 the Cotton Rose, (Filago.) 



ORDER V. SYNGENESIA SEGREGATA. 



In this order the florets contain both pistils and stamens, 

 but contrary to the other orders, each floret has its own 

 calyx, or perianth separate from the general, or common 

 calyx, which only is found in the other orders ; hence the 

 name Segregata, which means separated. This is a small 

 order, and contains no plants of any impoitance. Elephant's 

 foot, (Elephantopus,) and Globe Thistle, (Echinops,) are the 

 principal genera. One species of the former, (E. Carolinia- 

 nus,) is the only plant of this order contained in the cata- 

 logues of American Plants. 



CLASS XX. GYNANDRIA. Orders 3. 



The name of this class signifies pistils, and Fi s- 



stamens, in reference to their both growing 

 together. The stamens are placed on the 

 pistils, or germen. 



The singular plants which constitute this 

 class, are distinguished from all others by the 

 anomalous structure of their flowers. These 

 do not, as is usually the case, contain a cer- 

 tain number of stamens surrounding a central 

 ovarium, (germen,) or style, but on the con- 

 rary, are furnished with a solitary, fleshy, un- 

 divided process, round which the sepals, (leaves of the calyx,) 



In the order Necessaria, which of the florets contain stamens, and 

 which contain pistils V What are the characters of the order Segresntf* r 

 What does the word Gynandria signify ? 

 17 



