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GENERAL NOTES.

BOTANY.

INSECTS NEEDED TO FERTILIZE UTRICULARIA AND PYXIDANTHERA .
- In a short paper read at the American Association, in
Buffalo, in 1876, I showed some of the neat arrangements by
which a cross-fertilization of flowers was secured in several species
of several genera of plants. I now present an illustration of one
of the best of these. It is the common bladderwort, Utricularia
vulgaris, which is common in stagnant ponds. Aside from the
peculiarity under consideration, there are several other things
about the plant of especial interest.

Fig. I shows an enlarged front view of the flower with the
lower tip pulled down. The lower tip of the stigma is much
the larger, and when touched it bends up in a few seconds close
against the upper lip of the corolla just under an arch-like projection. On visiting a flower for honey, an insect, as a honey-bee,
can scarcely fail to hit the larger of the two stigmas. Farther
on pollen is received on the tongue or jaws of an insect. None
is likely to be left on the stigmas of the same flower, for by the

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time the insect is ready to withdraw, the side of the stigma which

FIG. I .- An enlarged front
view of a flower of Utricularia vulgaris. 
s, outside of the larger sensitive stigma after it has closed under the ridge on the corolla. 
a, anthers. 
l, lower lip of corolla pulled down.

FIG 2 .- Side view of the same flower showing the position of the larger stigma before it has been touched by an object.

FIG 3 .- Side view of pistil still further enlarged, showing the larger stigma a few seconds after it has been disturbed.

is ready to receive pollen is hidden or covered. Hardly any
method can be more admirable for securing a cross-fertilization
of flowers.
Some time in April I received from the pine barrens of New
Jersey a large plant in flower of Pyxidanthera barbulata. This
was placed near the window on a dinner plate containing some
water. The plant continued to produce an abundance of fresh

Fig. 1.  Flower of Pyxidanthera barbulata, enlarged. Two of the sepals are removed. The two beaked anthers shown between the petals.
Fig. 2. Oblique view of stamen, showing beaks and transverse opening in anthers.
Fig. 3. Side view of stamen.

flowers for ten days or more.  The small white flowers when

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open look much like a small phlox, to which the plant is nearly
allied. There are five stamens alternating with the lobes of the
corolla, to which they are attached. The anthers are about as
high as the stigma, towards which each one projects two short
beaks. On pressing these beaks down with a pin, a mass of
pollen oozes out of each transverse slit of the anther. After re-
moving the pin, the beaks will again and again resume their
places and the opening will close. After they were well open, I
marked several fresh flowers and watched them two or three times
a day for four or five days. In no case did any pollen escape
from the anthers. These finally withered and shrunk up considerably, and the whole corolla, stamens and all, seemed to be lifted above the rest of the flower by the elongation of the calyx
or some other cause.

This case seems to be dependent on insects for aid in fertilization. It is possible that fresh plants in their native place would
not behave as did these sent by mail, but I think they would.
If so, this queer plant is another of the hosts of plants which have
a special contrivance by which insects are needed to aid in transferring pollen .- Prof. W. F. Beal.