` INEQUILATERAL LEAVES. 573 
available for the parts when unfolded affect them; and how far 
the parts are rendered unlike by unlikenesses in their relations to 
light, it is difficult to say. Probably, these several factors oper- 
ate in all varieties, of proportion.” He attributes the want of 
symmetry in the leaves of the Lime tree or basswood to the shad- 
ing of the smallest lobes. That this cannot be the case is proven 
by an examination of the conduplicate leaves of the basswood and 
elm while in the bud. When less than half an inch in length, 
the lobes are plainly unequal. When much less than a fourth of 
an inch long they are nearly or quite equal lobed. Since noticing 
these facts, the writer was pleased to find the same views recorded 
rr. Wi 
On the basswood, the leaves are alternate and two ranked, 
having the upper lobe fullest. This is the case even where the 
Fig. 101. 
Alternate two ranked leaves of Tilia Americana, Basswood, fullest at the base 
on the inner side. 
full lobe is shaded or where the whole leaf is well exposed to the 
light. Spencer gives an illustration showing the arrangemennt of 
basswood leaves, exposing nearly all their upper surface to the 
light. If he should turn a young branch over, of this or almost 
any other plant, he might be surprised to see how soon the leaves 
would turn back again, and how nicely they would adapt them- 
selves to each other, economizing all the available space. 
leaves of red elm and the American elm are sessile, broad at the 
base, two ranked with the upper lobe fullest. The same is true of 
the blue beech, Carpinus Americana, though the lobes are often 
Saran oer occidentalis has two ranked leaves with petioles 
h long. The upper lobes of the leaves are very full 
when weal with those of the elm. Begonia leaves are two 
