Plants of bladderwort lack roots. The plant is comprised wholly of a stem system which bears bladders upon at least some of its parts. These bladders trap small animals which are therein digested. The plants of most species are submersed and free-floating or fixed by root-like appendages in the soil (thus appearing rooted). Stems are capillary-dissected, alternate or whorled. In a few species that grow within a soil substrate, emergent leaf-like branches are grass-blade-like or have a rosette of emergent obovate-spatulate to orbicular branchlets. The flowers are 1 to several on slender scapes that are above the water. In some species, the flowering scape has a whorl of inflated branchlets about midway its length. These float and hold the scape with its flowers above the water surface (U. inflata Walt., Floating bladderwort). The flowers are yellow (U. inflata, and U. gibba L., Cone-spur bladderwort), yellowish white, pink or purple (U. purpurea Walt., Purple bladderwort), often showy with a conspicuous projecting lower lip that is spurred at the base in front. A bract or a pair of bractlets sometimes are present on the flower stalks. The fruit is a capsule containing minute seeds.
Habitat/Growth Characteristics:
Plants may be found growing in ponds, lakes, on river shores, pools and ponds in woods, marshes, ditches, slow moving streams, and bogs. One species, U. inflata, is known to produce tubers. Some species form terminal winter buds or turions which are small, very crowded "leaves" by which the plants overwinter. Plants may also reproduce by seed and vegetatively by fragmentation
Like Venus Flytraps, aquatic bladderworts have an active trapping mechanism to capture their prey. The bladder-like traps are located all along the plant. To set a trap, a trap door is sealed shut and the plant pumps out the water to create a vacuum-filled chamber. Outside of the chamber are very sensitive trigger hairs. When a tiny critter, such as a water flea, touches a trigger hair, the trapdoor swings open and the vacuum in the chamber literally sucks the critter right in.
As the name implies, aquatic bladderworts grows in water. No soil is needed because these plants are rootless. They literally float in the water. Seeing this plant in the wild, you might easily mistaken it as a pondweed. Migrating waterfowl, such as ducks and geese, think of it as a very nutritious meal!
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