The summer which is allowed to pass without a visit to the twilight
haunt of the evening primrose, perhaps at your very door, is an
opportunity missed. Night after night for weeks it breathes its
fragrant invitation as its luminous blooms flash out one by one from
the clusters of buds in the gloom, as though in eager response to the
touch of some wandering sprite, until the darkness is lit up with
their luminous galaxy--that beautiful episode of blossom-consciousness
and hope so picturesquely described by Keats:
"A tuft of evening primroses
O'er which the wind may hover till it dozes,
O'er which it well might take a pleasant sleep,
But that 'tis ever startled by the leap
Of buds into ripe flowers."
Nor is it necessary to brave the night air to witness this sudden
transformation. A cluster of the flowers placed in a vase beneath an
evening lamp will reveal the episode, though robbed of the poetic
attribute of their natural sombre environment and the murmuring
response of the twilight moth, a companion to which its form, its
color, and its breath of perfume and impulsive greeting are but the
expression of a beautiful divine affinity.
Then there is that pretty daylight mystery of the faded, drooping
bells of last night's impulsive blossoms, each perhaps tenanted by the
tiny, faithful moth which first welcomed its open twilight chalice,
and which now has crept close within its wilted cup, the yellow tips
of its protruding wings simulating the fading petals. And again, a few
weeks later, with what surprise do we discover that these long columns
of green seed-pods are not always what they seem, but are intermingled
with or supplanted by smooth, green caterpillars which exactly
resemble them in size and general shape, the progeny of our tiny pink
and yellow moth now feeding on the young seed-pods! Verily even a
vireo or worm-eating warbler, who is supposed to know a green
caterpillar when he sees one, might perch among these without a
suspicion, except perhaps at the tickling of its feet by the rudely
touched victim.
But these are not all the interesting features of the evening
primrose. It has still another curious secret, which has doubtless
puzzled many a country stroller, and which is suggested in the
following inquiry from a rural correspondent:
"I read in 'Harper's Young People' your piece about the evening
primrose, and found the little moth and the catterpilers, what
I never seen before; but they is one thing what you never tole
us about yit. Why is it that the buds on so meny evening
primroses swell up so big and never open? Some of them has
holes into them, but I never seen nothing cum out."
This same question must have been mentally propounded by many
observers who have noted this singular peculiarity of the buds--two
sorts of buds, one of them long and slender, and with a longer tube;
the other short and stout, with no tube at all--both of which are
shown in proper proportion in my illustration. It is well to contrast
their outward form, and to note wherein they differ. In the normal or
longer bud the tube is slender, and extended to a length of an inch or
more, while in the shorter specimen this portion is reduced to about a
fifth or sixth of that length, while the corolla enclosed within its
sepals is much shortened and swollen.
The difference in the shape and development of these two buds is a
most interesting study, as bearing upon the conscious intention of
the flower as an embodiment of a divine companion to an insect. What
is the intention involved in the construction and habit of this
flower? Why this long tube? Why does it await the twilight to burst
into bloom?
In the new botany of Darwin flowers must be considered as embodiments
of welcome to insects. Long ago it was discovered that the powdery
pollen of a flower must reach the stigma of the flower in order to
produce seed. It was formerly supposed that this was naturally
accomplished by the stamens shedding this pollen directly upon the
stigma, but this was later shown to be impossible in most flowers, the
anthers containing the pollen being so placed that they could not thus
convey the pollen. This fact was first noted by Sprengel in 1787, who
was the first to discover that the flower, with its color, perfume,
and honey, was really designed to attract insects, and that only by
their unconscious aid could the pollen be thus carried to the stigma.
But Sprengel had supposed that the intention of the blossom was the
reception of its _own_ pollen, a fact which was again soon seen to be
impossible, as the stigmas of many flowers are closed when their own
pollen is being shed. It remained for Darwin seventy years later to
interpret the problem. Insects were intentionally attracted to the
flower; but the pollen with which their bodies thus became dusted was
designed to be carried to the stigmas of another flower, showing
cross-fertilization to be the intention in nearly all blossoms.
The endless shapes of flowers were shown by Darwin to have reference
to certain insects upon whom the flower depended for the transfer of
its pollen. What are we to infer from the shape of our evening
primrose? Its tube is long and slender, and the nectar is secreted at
its farthest extremity. Only a tongue an inch or so in length could
reach it. What insects have tongues of this length? Moths and
butterflies. The primrose blooms at night, when butterflies are
asleep, and is thus clearly adapted to moths. The flower opens; its
stigma is closed; the projecting stamens scatter the loose pollen upon
the moth as it sips close at the blossom's throat, and as it flies
from flower to flower it conveys it to other blossoms whose stigmas
are matured. The expression of the normal bud is thus one of affinity
and hope.
Our friend just quoted mentions having seen "holes" on the other
swollen buds, and there is certain to be a hole in every one of them
at its maturity. But let us select one which is as yet entire. If with
a sharp knife-point we cut gently through its walls, we disclose the
curious secret of its abnormal shape--"the worm i' the bud," as shown
in my accompanying sketch--and what an eloquent story of blighted
hopes its interior condition reveals! This tiny whitish caterpillar
which we disclose in the petal dungeon has been a prisoner since its
birth, during the early growth of the bud. One by one the stamens and
also the stigma have been devoured for food, until the mere vestiges
of them now remain. With no stamens to bequeath pollen, and no stigma
to welcome other pollen, what need to open? What need to elongate a
corolla tube for the tongue of a moth whose visit could render no
functional service? So thus our blighted buds refuse to open, where
blooming would be but a mockery. This tiny caterpillar has a host of
evening primrose blossoms laid to his door. When full grown he is
nearly a third of an inch in length, at which time he concludes to
leave his life-long abode, which explains the "hole" through the base
of the bud. If we gather a few of these buds and place them in a small
box, we may observe the remaining life history of the insect. After
creeping from its petal home it immediately spins a delicate white
silken cocoon, and within a day or so changes to a chrysalis. At the
expiration of about a fortnight, as we open the box, we are apt to
liberate one or more tiny gray moths, which upon examination we are
bound to confess are a poor recompense for the blossom for which they
are the substitute.
This little moth is shown very much enlarged in the accompanying
illustration. Its upper wings are variously mottled with gray and
light brown, and thickly fringed at their tips, while the two lower
wings are like individual feathers, fringed on both sides of a narrow
central.
These and other characters ally the insect with the great group known
as the _Tineidae_, of which the common clothes moth is a notorious
example.