1. Utricularia
L. (bladderwort)
(P. Taylor, 1989)
Plants annual or
perennial, lacking true roots, with slender branched stems, some of these
sometimes stoloniferous. Leaves (these sometimes interpreted as systems of
flattened branches) absent or more commonly alternate (opposite or whorled
elsewhere), sessile or short-petiolate, glabrous. Stipules absent. Leaf blades
entire or dichotomously and/or pinnately dissected into few to numerous linear
lobes. Traps few to numerous, small, globose to saclike, attached mostly
laterally along the leaf divisions. Inflorescences racemes or sometimes reduced
to a solitary flower, usually with a relatively short axis and a long stalk,
the flowers subtended by small bracts, these also usually scattered along the
inflorescence stalk. Flowers perfect, hypogynous. Calyces deeply divided into 2
lobes, the upper lobe often slightly broader than the lower one, persistent at
fruiting. Corollas zygomorphic, 2-lipped with a very short tube, the lower lip
with a raised, folded, and/or inflated, often slightly 2-lobed “palate” of
tissue, which effectively closes the corolla throat, and a conic to narrowly
cylindric spur at the base (this usually angled forward under the corolla).
Stamens 2, attached at the tip of the corolla tube, the filaments short, the
anthers attached at the midpoint. Pistil 1 per flower, of 2 carpels, the ovary
superior, 1-locular, with free-central or basal placentation, the ovules
numerous. Style 1, short, the stigma 2-lobed. Fruits capsules, with numerous
tiny brown seeds. About 214 species, nearly worldwide.
Utricularia is the only genus of carnivorous plants
to be reported thus far from Missouri. The traps generally operate by a suction
mechanism, this triggered by disturbance to a pair of minute hairlike
appendages located along the rim. Glands inside the trap secrete substances
that digest the prey or other organic matter that may have entered the trap.
Prey organisms are mostly minute aquatic or soilborne invertebrates and
microorganisms.