Rumex 



POLYGONACEAE 



407 



50 



Map 828 



Rumex triangulivalvis 

 (Danser ) Rech. f. 



50 



Map 829 



Rumex Britannica L. 



50 



Map 830 



Rumex crispus L. 



ground in cultivated fields, along streams, and in woodland on the border 

 of swamps, ponds, and sloughs. It is one of our most obnoxious weeds. 

 The root was formerly official in medicine and was sold usually under 

 the name of yellow dock. Formerly the early spring leaves were mixed 

 with those of the dandelion and cooked for food. The mixture was called 

 "greens." The discovery, however, that the leaves contain calcium oxalate, 

 which is injurious, has decreased the popularity of this practice. 



The farmers in Indiana usually call this plant sour dock. 



The tubercles of the valves of the same plant may vary at the apex 

 from obtuse to acute. Rumex elongatus Guss. is a form of this species 

 with acute tubercles but since both acute and obtuse forms can be found 

 on the same plant, all reports for this species should be referred to Rumex 

 crispiis. 



Nat. of Eu. Now found throughout temperate N. A. 



7. Rumex obtusifolius L. Bluntleaf Dock. Map 831. Infrequent to 

 frequent throughout the state. It is found almost everywhere in moist 

 or rather moist soil in open woodland, fallow fields, and wasteland and 

 along roadsides. The veins of the leaves of this species are sometimes 

 red and I think our reports for Rumex sanguineus should be referred 

 to this species. 



Nat. of Eu. ; Newf. to B. C. and Oreg., southw. to Fla. and Tex. 



2201. POLYGONUM [Tourn.] L. Knotweed, Smartweed 



[Some recent authors divide this genus into several small genera. Since 

 I am following Dalla Torre and Harms I am not dividing the genus.] 



A. Plants not twining. 



B. Stems not armed with prickles. 



C. Flowers axillary (solitary or in clusters). 

 Stems and branches terete and striate. 



Plants erect, mostly 0.4-1.5 m high, rather sparsely branched, the branches 



