Bladderworts (Utricularia)

Utricularia (also known as bladderworts) are one of the most diverse and bizarre groups of carnivorous plants. Found on all continents except Antarctica, they capture prey with an elaborate bladder trap that sucks in the tiny insects and nematodes that make up most of their diets. In cultivation Utricularia are mostly grown for their flowers, many of which resemble tiny orchid blooms. Some of the more dramatic South American species have large flowers and foliage, and can make for spectacular specimen plants.

The most common way to divide Utricularia is into three groups: aquatic species, terrestrial species, and epiphytic species. The aquatic species grow fully submerged in water, sometimes attached to the bottom and sometimes free-floating. These tend to have the largest traps, and some have become invasive weeds in various waterways. Terrestrial species are usually found in very wet, saturated soil, and may occasionally be submerged by shifting water levels. Most terrestrial species have very tiny "leaves", and can usually only be identified when they flower. The epiphytic species are mostly found in South America, where they grow on rocks and trees in high elevation cloud forests. These are usually the largest and showiest species, and have incredible flowers.

Besides their strange traps, Utricularia are also unique in having mostly undifferentiated tissue, meaning there is no clear distinction between leaves, stem, and roots. In the water or under the soil they usually produce stolons, which are root-like runners that might create bladder traps or shoot up the photosynthetic tissue that stands in for leaves. Utricularia are usually propagated by dividing up these stolons into new soil, where they will continue to grow and expand.

While species like U. bisquamata and U. subulata are very common in cultivation (even becoming weeds in certain collections), many species of Utricularia are very rare, and can be difficult to acquire and then flower. However, for their strange growth and beautiful flowers they are a must-have for collectors of rare plants.