300 CLASS XIX. ORDER I. 



323. Apargia, Receptacle naked ; calyx imbri- 

 cate ; down feathery, sessile. 



324. Leontodon. Receptacle naked ; calyx imbri- 

 cate, with flaccid scales; down simple, pedicelled. 



325. Prenanthes, Receptacle naked ; down sim- 

 ple ; calyx in^'csted with scales; florets few, in one 

 row. 



326. Lactuca. Receptacle naked ; down simple, 

 pedicelled ; calyx imbricate, cylindrical, scarions at 

 the margin. 



327. HiERACiuM. Receptacle naked, dotted ; down 

 simple, sessile ; calyx imbricate, ovate. 



328. Krigia. Receptacle naked ; down of five 

 membranous leaves, alternating with five bristles ; 

 calyx simple, many leaved. 



329. SoNCHUs. Receptacle naked; down simple, 

 sessile; calyx imbricate, swelHng at the base. 



B. Flowers in heads. 



330. Arctium. Receptacle chafl'y; down bristly 

 and chaflTy; corolla floscular ; calyx globular with 

 hooks on the top of the scales. 



331. Cnicus. Receptacle villous; down feathery; 

 corolla floscular; calyx swelling, with spinous scales, 



332. Onopordon. Receptacle cellular ; down ca- 

 pillary; corolla floscular ; calyxswelling with spinous 

 scales. 



333. LiATRTs. Receptacle naked ; down feathery, 

 colored ; calyx oblong, imbricated. 



334. Vernonia. Receptacle naked; down double, 

 the outer chaffy, inner capillary; corolla floscular; 

 calyx ovate, imbricate. 



C. Florets tubular. 



335. BiDENs. Receptacle chafl'y, flat; seeds angu- 



