IOWA ACADEMY OF SCIENCES. 251 



585. S. palustris {]j.) Hook. Occasionally appearing in 



marshes and around lakes. 

 Arctium L. 



586. A. lappa L. Burdock. Waste places; introduced 



from Europe. 

 Cnicus L. 



587. C. ioirensis Pamrnel. Our commonest thistle; 



woods and prairies. 



588. 0. ioirensis cratfi/i Paramel. Woods and prairies; 



less common than the species. For a descrip- 

 tion of this and the preceding, see Proc. Iowa 

 Acad. Sciences, VIII, p. 231. 



589. C. canescens (Nutt.) Pammel. (C iindn/atns var. 



canescens Grray; Cirsium canescens Nutt.) A per- 

 ennial thistle growing in patches, and becoming 

 more plentiful. 



590. C. UinceoIafHs (L.) Willd. [Cardmis lajireolatiis L.) 



Common Pasture Thistle. Fields and waste 

 places; naturalized from Europe. 



