The leaves are broad and cordate (heart-shaped), the largest
measuring about five inches each way. If we remember how suc-
culent all the parts of the plant are and how much water it there-
fore requires, we can easily see the advantage the plant derives
from the largeness of its leaves. Large leaves cover more ground
than small ones; hence, they prevent evaporation of water from
the soil in a greater measure than could be done by smaller leaves.
Large leaves are lable to be torn by the wind much more
easily than small ones; and in heart-shaped leaves like those of
the Cucumber the weakest part is the base. Therefore this parti-
cular part is specially strengthened: there are five or seven
strong ribs issuing from the base of the leaf like fingers from the
palm of the hand, and two of them form the margin of the leaves
for a small stretch like the hem of a garment.
5. The Flowers rise singly or in small clusters from the
axils of the leaves. The calyx and the yellow corolla are com-
bined at their base. The corolla forms a five-lobed bell. So far,
all flowers of the plant are alike. But if we proceed to examine
their stamens and pistils, we find that most of the flowers have
only stamens (fig. 77, 1), whilst some have only pistils (fig. 77, 2).
The former are known as staminate or male flowers, the latter as


76 DICOTYLEDONS


pistillate or female flowers, The flowers, then, are unisexual.
