42 
IOWA ACADEMY OP SCIENCE 
It sometimes is an escape. The service » berry (Amelanchier 
canadensis) usually referred to this species is not common, but 
is reported from South Dakota opposite Woodbury county by 
Mrs. Taylor and from Lyon county by Shimek. The A. spicata 
occurs in the Okoboji and Spirit Lake region. Probably all of 
the forms on the shores of the lakes of northern Iowa should 
be referred to this species rather than to A. alnifolia of the 
west. The most common, if not the only haw in the region, is 
Crataegus mollis. The C. punctata is reported from Ida and 
Sac counties by Macbride. It probably occurred in the Missis- 
sippi drainage area. The C. coccinea is also reported ; its occur- 
rence in the northwest is doubtful. It is not common to the Mis- 
souri basin flora. It was found by one of us (Pammel) on the 
Little Sioux near Sioux Rapids. Of the oak family {Fagaceae) 
six species are recorded. The most common and widely distrib- 
uted is the bur oak {Quercus macrocarpa) which occurs from 
Fremont to Lyon counties. The var. olivaeformis which one of 
us recorded (Pammel) is probably only a form of Q. macrocarpa. 
The Q. rubra occurs from Fremont to Dickinson counties but is 
nowhere common except southwest. Evidently it is an invasion 
from the south. The Q. velutina recorded by Shimek is very 
local in Harrison county near Logan. The chestnut oak {Quer- 
cus acuminata) occurs in Fremont county. It will also be 
found probably in Mills county. The Q. imbricaria though not 
observed by us, is said to occur in Fremont county. The only 
tree representative of the family Betulaceae is the iron wood 
(Ostrya virginiana) which is fairly common in the region, per- 
haps more abundant southward than northward. Of the family 
Salicaceae there is only one poplar common, namely the Cot- 
tonwood {Populus deltoides). The quaking aspen (P. tremu- 
loides) is reported from Osceola, Dickinson, Sac and Ida coun- 
ties. Here the species belongs in part to the Mississippian flora. 
A part of these counties are drained to the Mississippi and a 
part to the Missouri. It has been reported from Fremont county 
by von Bayer, from Ringgold and Union counties by the Fitz- 
patricks. It also occurs in the Lake Okoboji region though it is 
not common. These belong to the Missouri basin. Of the wil- 
lows the B. amygdaloides and S. nigra and fluviatilis are com- 
mon in the region. The 8 . amygdaloides and 8. nigra belong to 
the southern flora. The 8. missouriensis belongs to the west and 
south. The 8. cordata and 8. discolor are northern. The Tilia 
