218 iowa academy of sciences. 



Salix L. 



193. aS*. nigra Marsh. Black Willow. Frequent alonor 



streams. 



194. S. amygdaloides Anders. Peach-leaved Willow. 



Common throughout, near lakes and streams. 



195. S. alhu vitellina (L.) Koch. White Willow. This 



European form is commonly cultivated through- 

 out this region, and is frequent as an escape. 



196. S. Jfiiriafilis Nutt. (*S'. hugifoUa Muhl.) Sand- 



bar Willow. One of our most common species. 



197. *S'. hum His Marsh. A pretty little shrub, rare in 



the border of woods, and on the prairies, 



198. S. discolor Marsh. Pussy Willow. A pretty 



shrub, or low tree; frequent in low ground. 



199. S. cordata Muhl. Heart-leaved Willow. Very 



common along streams, and on low prairies. 



200. -S'. mi/rfilloides L. Bog Willow. This northern 



species, from one to three feet high, occurs in 

 a bog two miles north of Armstrong, the only 

 locality known in the state. 



BETULACE.^. 

 OSTRYA Scop. 



201. 0. virgin iafta (MiW.) WiWd. Hop Hornbeam, Iron- 



wood. A small tree common in woods. 



CORYLUS L. 



202. C. americana Walt. Hazel-nut. Frequent on the 



edges of woods, but much less common than 

 farther east. 



FAGACE^. 

 QUERCUS L. 



203. Q. ruhra L. Red Oak. Common in the woods in 



the western part of the county. 



204. Q. macrocMrpa Michx. Bur Oak. Our commonest 



native tree; a species which exhibits the pioneer 

 spirit, reaching owt into the prairies in advance 

 of any other of the hard wood trees. 



