266 
IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
Balm of Gilead (Populus candicans Ait.), introduced. 
Cottonwood (Populus deltoides Marsh), low lands, common. 
Butternut (Juglans cinerea E.), common, slopes of hills. 
Black walnut {Juglans nigra L), common, alluvial bottoms, and 
lower slope of hills. 
Shellbark hickory {Cary a ovata (Mill) K. Koch), common, 
upland woods. 
Pignut hickory {Carya cordiformis (Wang) K. Koch), com- 
mon. 
Hop hornbeam {Ostrya Virginiana (Mill) Koch), common. 
Ironwood or blue beech {Carpinus caroliniana Walt), shady 
slopes. 
Cherry, yellow or gray birch {Betula lutea Michx), sandy, 
moist ravines below Pikes Peak, Yellow river region. 
Black or river birch {Betula nigra L.), Mississippi river bot- 
toms. 
Paper birch {Betula papyrifera Marsh), common, limestone 
bluffs. 
White oak {Quercus alba L), common, upland woods. 
Bur oak {Quercus macrocarpa Michx), common. 
Swamp white oak {Quercus bicolor Willd), common, Missis- 
sippi river bottoms. 
Chestnut oak {Quercus Muhlenbergii Engelm), exposed slopes 
of hills. 
Red oak {Quercus rubra L.), common. 
Yellow oak {Quercus ellipsoidalis E. J. Hill), sandy soil. 
Quercitron oak {Quercus velutina Earn), sandy soil and sandy 
washes. 
Slippery elm {Ulmus fulva Michx), common in upland woods. 
American or white elm {Ulmus americana E.), along streams 
and in alluvial bottoms, common. 
Hackberry {Celtis occidentalis E.), common along streams and 
bottoms. 
Red mulberry {Morus rubra E.), not infrequent, upland woods, 
along Mississippi river. 
Papaw {Asimina triloba Dunal), Mr. Kenyon, formerly in 
nursery business at McGregor, reported the species at McGregor, 
supposed to have been planted there by the Indians. 
Sycamore {Platanus occidentalis E.), a few trees south of 
McGregor, mouth of Turkey river, rare. 
Wild crab {Pyrus ioensis (Wood) Bailey), common in woods 
forming thickets. 
