lants, growing in boggy
land over pretty much the whole world. They are represented in
the United States by several species of sundew (_Drosera_), and the
still more curious Venus's-flytrap (_Dionaea_) of North Carolina. The
leaves of the latter are sensitive, and composed of two parts which
snap together like a steel trap. If an insect lights upon the leaf,
and touches certain hairs upon its upper surface, the two parts snap
together, holding the insect tightly. A digestive fluid is secreted by
glands upon the inner surface of the leaf, and in a short time the
captured insect is actually digested and absorbed by the leaves. The
same process takes place in the sundew (Fig. 104, _N_) where, however,
the mechanism is somewhat different. Here the tentacles, with which
the leaf is studded, secrete a sticky fluid which holds any small
insect that may light upon it. The tentacles now slowly bend inward
and finally the edges of the leaf as well, until the captured insect
is firmly held, when a digestive process, similar to that in _Dionoea_,
takes place. This curious habit is probably to be explained from the
position where the plant grows, the roots being in water where there
does not seem to be a sufficient supply of nitrogenous matter for the
wants of the plant, which supplements the supply from the bodies of
the captured insects.

[Illustration: FIG. 105.--Types of _Aphanocyclae_ (_Cistiflorae_). _A_,
_B_, leaves of the pitcher-plant, _Sarracenia_ (_Sarraceniaceae_). _A_,
from the side; _B_, from in front, x 1/2. _C_, St. John's-wort
(_Hypericum_), x 1/2. _D_, a flower, x 1. _E_, the pistil, x 2. _G_,
cross-section of the ovary, x 4. _H_, diagram of the flower.]

Similar in their habits, but differing much in appearance from the
sundews, are the pitcher-plants (_Sarraceniaceae_), of which one
species (_Sarracenia purpurea_) is very common in peat bogs throughout
the northern United States. In this species (Fig. 105, _A_, _B_), the
leaves form a rosette, from the centre of which arises in early summer
a tall stalk bearing a single, large, nodding, dark-reddish flower
with a curious umbrella-shaped pistil. The leaf stalk is hollow and
swollen, with a broad wing on one side, and the blade of the leaf
forms a sort of hood at the top. The interior of the pitcher is
covered above with stiff, downward-pointing hairs, while below it is
very smooth. Insects readily enter the pitcher, but on attempting to
get out, the smooth, slip