The New England Carnivorous Plant Society www.NECPS.org TheThe BladderwortBladderwort Utricularia

Bladderwort is the common name given to the plants of the genus Utricularia, the largest genus of carnivorous plants. There are over two hundred species found in fresh water and wet soil. Bladderworts are most often cultivated for their flowers, which are often compared with those of snapdragons and orchids. The anatomy also diverges greatly from the usual plant structures: they have no true roots, their leaves are considered by many to not be true leaves at all, and stems are nearly absent in all but the most primitive species. Most bladderworts are very small clusters of plants.

Tuberous Utricularia are native to Australia, and grow only during the wet, cool winters. When drying, hot conditions arrive in summer, the plants go dormant and form underground tubers, which store up energy for the next growing season.

How They Trap Food: The tiny trapping devices of Utricularia are usually buried within the soil, or in the case of aquatic species, tangled in floating masses of aquatic weeds. Tiny though it may be, its complexity is unrivalled in the world of carnivorous plants. It consists of a sac, (usually between .5 and 2 mm, although giants of the genus can reach a whole centimeter), with an inward-opening trapdoor on one side, levered by tiny trigger-hairs. The plant pumps water out of the sac, creating a lower pressure inside the trap. When an unsuspecting organism of suitable scale ventures too near and trips one of the trigger hairs, the door opens, the victim is sucked in, and the door shuts behind it. The whole process can occur within ten to fifteen thousandths of a second. Once inside enzymes secreted by the plant digest the prey, and the resulting nutrients are absorbed.

Typical Prey: Terrestrial species tend to have tiny traps, and feed on minute prey such as protozoa and rotifers swimming in water-saturated soil. However, in aquatic species, the bladders are larger (sometimes exceeding 5 mm in diameter) and can feed on more substantial prey such as water fleas (Daphnia) and even fish fry, mosquito larvae and new tadpoles.

Where it Lives: Bladderworts are found on every continent in the world except Antarctica.

Basic Care: Most Utricularia are generally easy to grow. Many people use the tray method to grow them. Most prefer wet potting media, so they can be grown in undrained containers. Occasional flooding of the container may induce flowering in some species. Terrestrial varieties like a 1:1 mix of sand and peat moss and to be kept wet. Epiphytes like a loose, open mixture such as an equal mix of sphagnum moss, orchid bark, perlite, sand, and a bit of peat moss. Tuberous varieties need a sandy mixture of 2 parts horticultural sand to 1 part peat moss. Most can easily be grown in a terrarium provided with artificial lighting.