OF THE LINNJEAN SYSTEM. 37 



presents nothing but flat or strap-shaped florets, notch- 

 ed at the extremity ; they may, in fact, be properly 

 considered as so many ordinary florets, with the di- 

 visions so closely united, as merely to be ascertained 

 by the number of teeth at the extremity of the strap, 

 but with the whole tubular corolla split open to the 

 base, so as, at first glance, to resemble a single petal, 

 or component of an ordinary flower. This tribe, the 

 ligulatce, are also curiously distinguished from the 

 preceding, or flosculosce, by the physical character of 

 giving out a milky juice on being wounded, which 

 juice partakes, more or less, of the nature of opium, 

 a drug which we derive from a very different family 

 of plants. 



In the second order, termed Superflua, as you 

 will perceive in the Daisy, Aster, and African Mary- 

 gold, the florets of the centre or disc of the flower 

 are all perfect, while the flat florets, which form the 

 ray, are merely pistilliferous, and without stamens ; 

 but in this order, to distinguish it from Necessaria, all 

 the florets perfect seed. Most of the radiate, or 

 bordered compound flowers with which you will meet, 

 belong to this common order. 



In the third order, called Frustranea, of which 

 you will find an example in the Sunflower and the 

 Rudbeckia, the disc, as in the preceding order, 

 affords perfect flowers, but the rays, excepting an 

 imperfect rudiment of seed, are reduced to mere 

 petals, and have no style. 



The fourth order, Necessaria, (of which there are 

 but few examples in nature, and none which you can 

 more readily examine than the common single Mary- 

 gold,) presents a disc of florets apparently perfect, 

 but not so in reality, as they are not succeeded by 

 seed, the rays only affording this prerequisite of fu- 

 ture existence. The five native genera, Silphium, 

 4 



