IOWA ACADEMY OP SCIENCES. 
219 
ULMACE^E. 
Ulmus L. 
205. U. americana L. White or Water Elm. Common 
along streams; one of our most desirable shade 
trees. 
206. TJ. falva Michx. Slippery Elm. Frequent. 
Celtis L. 
207. C. occidentalis L. Hackberry. Rather rare. 
MORACEJE. 
Cannabis L. 
208. C. sativa L. Hemp. A native of Europe and Asia, 
escaped from cultivation. 
URTICACE^E . 
Urtica L. 
209. U. gracilis Ait. Nettle. Common in woods, and 
introduced into rich ground near dwellings, 
where it is a troublesome weed. 
Urtioastrum Fabr. 
210. U. divarication (L) Kuntze. ( Laportea canadensis 
Gaud.) Common in woods. 
Adicea Raf. 
211. A. jpumila (L.) Raf. ( Pilea pnmila Gray.) Com- 
mon in low woods. 
Parietaria L. 
212. P. pennsglvanica Muhl. Infrequent, south shore 
of Iowa Lake. 
SANTALACEJE. 
COMANDRA Nutt. 
218. C. umbellata (L.) Nutt. Common on prairies. 
ARISTOLOCHIACE^:. 
Asarum L. 
214. A. canadense L. Wild Ginger. Rare in woods west 
of Estherville. 
