232 IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
acute through obtuse or rounded, to subcordate, or rarely quite 
cordate. 
Apex. — The apex of the leaf is by no means uniform. It has 
been described as usually acute ^ ; acute or acutish or rarely acumi- 
nate ; acute or acuminate ; acuminate ; 
and acute or slightly acuminate or obtusish 
Iowa specimens vary from short-acuminate through sub-acu- 
minate to acute, somewhat obtuse, distinctly obtuse or rounded. 
Few distinctly acuminate forms occur. The apex is often very 
variable in the leaves of the same plant. The same thing, how- 
ever, is also true of the other leaf characters. 
Margin. — The margin of the leaf is represented as serrate 
18 21 26 32 40 71 72 74 76 . finely Serrate finely and irregularly ser- 
rate ^ ; and toothed 
Most of the Iowa leaves are sharply, often finely serrate near 
the base, and serrate-dentate, serrate-crenate, crenate-dentate, or 
dentate towards the apex. Sometimes the teeth are quite irregular, 
and in all cases at least the younger leaves have the teeth black- 
tipped. 
Surface. — The surface of the leaf is exceedingly variable. 
It has been described as more or less villous pubescent ; very 
downy with soft hairs beneath ; finely pubescent, especially 
beneath ; more or less pubescent ; downy beneath ; some- 
what pubescent ; pubescent beneath ; pubescent — tending 
to become glabrous with age ; nearly glabrous above, canescently 
tomentose beneath ; nearly smooth above^ more or less velvety 
pubescent underneath ; pubescent beneath ; upper nearly smooth ; 
nerves quite hairy beneath, more or less ferruginous ; bright 
green and dull above, paler and pubescent or nearly glabrous be- 
neath 
The Iowa specimens exhibit equal variation. Some are densely 
pubescent on the lower surface, with short scattered loose or 
appressed hairs above; others have the lower surface densely 
pubescent while the upper is quite glabrous ; still others are pub- 
escent below, and on veins, only, above; and still others are 
glabrous above and pubescent only on the veins below. The 
young leaves are usually quite densely pubescent, but they often 
become nearly or quite glabrous above as they mature. 
Si^e. — The size of the leaf is also very variable, commonly 
on the same plant. The length of the blade is variously recorded 
as 1 to 3 inches to 3 inches^; to 2^ inches 2 to 3 
