218 
IOWA ACADEMY OF SCIENCES. 
Salix L. 
198. 8. nigra Marsh. Black Willow. Frequent along 
streams. 
194. S. amygdaloides Anders. Peach-leaved Willow. 
Common throughout, near lakes and streams. 
195. S. alba vitellina (L.) Koch. White Willow. This 
European form is commonly cultivated through- 
» out this region, and is frequent as an escape. 
196. S. fluviatilis Nutt. (S. longifolia Muhl.) Sand- 
bar Willow. One of our most common species. 
197. S. humilis 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. 8. cordata Muhl. Heart-leaved Willow. Very 
common along streams, and on low prairies. 
200. S. myrtilloides 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. 
BETULACEAEC . 
OSTRYA Scop. 
201. 0. virginiana (Mill.) Willd. Hop Hornbeam, Iron- 
wood. A small tree comtnon in woods. 
Corylus L. 
202. C. americana Walt. Hazel-nut. Frequent on the 
edges of woods, but much less common than 
farther east. 
FAGACEAS. 
Quercus L. 
208. Q. rubra L. Bed Oak. Common in the woods in 
the western part of the county. 
204. Q. macrocarjpa Michx. Bur Oak. Our commonest 
native tree ; a species which exhibits the pioneer 
spirit, reaching out into the prairies in advance 
of any other of the hard wood trees. 
