164 ORDER ^QUALIS. 



ing, at first, large, and somewhat downy heart-shaped 

 leaves ; and afterwards branching stems terminating 

 in a profusion of purplish flowers, inclosed in a globu- 

 lar calyx, covered with scales imbricated or tiled 

 over each other, and ending in hooked bristles, which 

 readily adhere to the hair of most animals, and prove 

 very troublesome. The receptacle is chaffy ; and 

 the pappus of a consistence betwixt bristles and 

 chaff. 



The Thistle ( Carduus), as to its general appear- 

 ance, is too well known to need description here ; but 

 its generic character is, to have a ventricose calyx, 

 formed of many imbricated scales ending in spines. 

 The receptacle is simply hairy. The pappus decidu- 

 ous (or easily separable from the seed), and either 

 hairy or plumose. From these the 



Onopordon, or Cotton Thistle, now naturalized in 

 wastes, in the northern states, differs principally, by 

 its pitted receptacle, which resembles a honey-comb. 

 The species, thus naturalized, is O. acanthium, which 

 may be known by its broad, ovate-oblong, decurrent, 

 sinuated, spiny leaves, woolly on either side. 



The Artichoke (Cynara) differs chiefly from the 

 Thistle in the structure of the calyx, the scales being 

 filmy and ragged on the edges, but fleshy, and termi- 

 nated by a channelled, emarginate, and pointed ap- 

 pendage. In this, and the 2 preceding genera, the 

 great size of the florets affords plain examples of the 

 structure of these compound flowers, but they differ 

 from most others in the undivided stigma. 



Related to the Thistle, through the medium of the 

 very proximate genus Serratula, is that of Vcrnonia, 

 peculiarly American. Most of the species, alike in 

 habit, are tall, coarse, and common plants, growing in 

 moist places, and by the banks of rivers, flowering in 

 autumn, and extending from the western parts of 



