GREATER BLADDERWORT HOODED WATERMILFOIL POPWEED
(Utricularia vulgaris) Bladderwort family
Flowers - Yellow, about 1/2 in. across, 3 to 20 on short pedicels
in a raceme at the top of a stout, naked scape 3 to 14 in. high.
Calyx deeply 2-lobed; corolla 2-lipped, the upper lip erect,
lower lip larger, its palate prominent, the lip slightly 3-lobed,
and spurred at the base; 2 stamens; 1 pistil; the stigma
2-lipped. Leaves: Very finely divided into threadlike segments,
bearing little air bladders.
Preferred Habitat - Floating free in ponds and slow streams, or
rooting in mud.
Flowering Season - June-August.
Distribution - Throughout nearly the whole of North America,
Cuba, and Mexico. Europe and Asia.
Here is an extraordinary little plant indeed, which, by its
amazing cleverness, now overruns the globe - one of the higher
order of intelligence so closely akin to the animals that the
gulf which separates such from them seems not very wide after
all. In studying the water-crowfoots (q.v.) and other aquatic
plants, we learned why submerged leaves must be so finely cut;
but what mean the little bladders tipped with bristles among the
pop-weed's threadlike foliage? Formerly these were regarded as
mere floats - a thoughtless theory, for branches without bladders
might have been observed floating perfectly. It is now known they
are traps for capturing tiny aquatic creatures: nearly every
bladder you examine under a microscope contains either minute
crustaceans or larvae, worms, or lower organisms, some perhaps
still alive, but most of them more or less advanced toward
putrefaction - a stage hastened, it is thought, by a secretion
within the bladders; for the plant cannot digest fresh food; it
can only absorb, through certain processes within the bladder's
walls, the fluid products of decay. The little insectivorous
sundew (q.v.), on the contrary, not only digests, but afterward
absorbs, animal matter. Tiny aquatic creatures, ever seeking
shelter from larger ones ready to devour them, enter the pop-weed
bladders by bending inward the free edge of the valve, which,
being strongly elastic, snaps shut again behind them instantly.
"Abandon hope, all ye who enter here," might be written above the
entrance. No victim ever escapes from that prison. Scientists are
not agreed that the bristles draw creatures into the bladder.
Whatever touches the sensitive valves is at once drawn in. "To
show how closely the edge fits," says Charles Darwin, "I may
mention that my son found a daphnia which had inserted one of its
antennae into the slit, and it was thus held fast during a whole
day. On three or four occasions I have seen long narrow larvae,
both dead and alive, wedged between the corner of the valve and
collar, with half their bodies within the bladder and half out.
Professor Cohn of Germany tells of immersing a plant of this
bladderwort one evening in clear water swarming with tiny
crustaceans, and by the next morning most of the bladders
contained them, entrapped and swimming around in their prisons.
So much for what is going on below the surface of the water: what
above it? Several flowers on the showy spike attract numerous
insects. One alighting on the lower lip must thrust his tongue
beneath the upper one to reach the nectar in the spur, passing on
its way the irritable stigma, which receives any pollen he has
brought in. Instantly it is touched, the stigma folds up to be
out of the way of the tongue when it is withdrawn from the spur
now laden with fresh pollen. It is thus that self-fertilization
is escaped. Many vigorous seeds follow in each capsule. This
marvelous piece of mechanism is what Thoreau termed "a
dirty-conditioned flower, like a sluttish woman with a gaudy
Not through its seeds alone, however, has the little plant
succeeded in firmly establishing itself. In early autumn the
stems terminate in large buds which, falling off, lie dormant all
winter at the bottom of the pond. In spring they root and put
forth leaves bearing bladders, which at this stage of existence
are filled with water to help anchor the plant. As flowering
season approaches, the bladders undergo an internal change to fit
them for a change of function; they now fill with air, when the
buoyed plant rises toward the surface to send up its flowering
scape, while the bladders proceed with their nefarious practices
to nourish it more abundantly while its system is heavily taxed.
The HORNED BLADDERWORT (U. cornuta), found in sandy swamps, along
the borders of ponds, marshy lake margins, and in bogs from
Newfoundland to Florida, westward to Minnesota and Texas, bears
from one to six deliciously fragrant yellow flowers on its
leafless scape from June to August. It is "perhaps the most
fragrant flower we have," says John Burroughs. "In a warm moist
atmosphere its odor is almost too strong.... Its perfume is sweet
and spicy in an eminent degree." The low scape, rooting in the
mud, has some root-like stems and branches, sometimes with a few
entire leaves and bladders. Its benefactors, bumblebees and
butterflies, with their highly developed aesthetic taste, are
attracted from afar by this pleasing flower, whose acute, curved
spur filled with nectar may not be drained by small fry, to whom
the hairy throat is an additional discouragement.
SWEET WILD HONEYSUCKLE, or WOODBINE; ITALIAN OR PERFOLIATE
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