This genus includes only one species, Aldrovanda vesiculosa L., the waterwheel plant. This is a small, free-floating, freshwater plant that, like the Venus fly trap, catches its prey using leaves that have been modified to become snap traps
Although this inconspicuous plant is actually native to Europe and grows in Asia, Africa, and xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />xml:namespace prefix = st1 />Australia, it was discovered only toward the end of the seventeenth century, in India. It was then brought to England, where Leonard Plukenet (1642-1706) kept it in the exotic plant collections of Queen Mary II, describing it in his three-volume work Almagesti Botanici Mantissa as "lenticula palustris indica." In 1747, Gaetano Lorenzo Monti (1712-1797) also found specimens of the waterwheel plant in lakes near Bologna, Italy. He dedicated the generic name to the Italian naturalist and physician Ulisse Aldrovandi (1522-1605), who established Bologna's botanical garden. The genus was originally called "Aldrovandia," but this was changed to "Aldrovanda," presumably through a spelling mistake, and was adoptedas such by Linnaeus in 1753 (Lloyd 1942).
Distribution and Habitat
Aldrovanda has a wide distribution in Europe. Africa, Asia, and Australia. The species occu only sporadically throughout this area, however. The distribution extends from France in the west to eastern Europe, Asia, and Australia. The waterwheel plant is found as far north as Lithuania, and in the south it reaches the Tropic of Capricorn in Africa and Australia. Most of the European
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Stem: The stem is about 2.4-4.7 inches (6-12 centimeters) long, but much shorter or longer plants should be noted with little more than a small raising of the eyebrows.
A new whorl of five to nine leaves is produced every 0.25 inch (0.6 centimeter) or so. As new whorls format the stem tip, the stem disintegrates at the end, sothe total stem length stays the same.
Trap: The leaves have little flat petioles that widen from the stem to their ends. At the tip each petiole bears a clam-like trap and several long bristles
Size: The entire leaf (including petiole and trap) is about 0.4-0.6 inch (1-1.5 centimeters) long, so the diameterof a shoot is about 0.8-1.2 inches (2-3 centimeters). The plant is about as large as your thumb! It grows rapidly, and in good conditions branches frequently. These branches eventually detach and become separate plants.
Flowers: Flowers are on short scapes that are borne slightly above the water surface.In good conditions a flower bud will appear from the stem and rise from underwater into open air. The flower is about 8 mm wide and consists of five sepals that are fused at the base, four white petals, five stamens, and a fused superior ovary consisting of five carpels. The bud usually does not develop further, A seed capsule develops and ripens underwater.
Seeds: The fruits mature within a few weeks and yieldabout one to seven seeds each. The seeds are black, glossy, and about 0.04-0.06 inch (1.1-1.5 millimeters) long. Germination is difficult and can take several months.
Proto-root: Students of botany know that the first structure to emerge from a seed is almost invariably the beginnings of a root system. In the case of Aldrovondo, the proto-root never grows more than 0.13 inch (3 millimeters) long. Aldrovondo's lifestyle as a rootless plant starts early!
Winter turions: Aldrovando's growth slows down in chilly conditions, and most strains form winter resting buds called turions perhaps 0.2-0.3 inch (5-8 millimeters) long. Turions can float near the water surface until spring, but usually they sink to the mucky pond bottom and avoid being locked in ice.
Special Topics for Aldrovanda
A number of different types of Aldrovonda exist in cultivation.
Two "red" strains of Australian Aldrovondo are quite attractive and very popular among growers, and a new popu lation of red Aldrovando was recently discovered by Robert Gibson in southwest Western Australia, bringing the number of known historical Austalian Aldrovandosites to fourteen. The foliage of the red strains is strongly pigmented red or purple if the plants are grown in adequate light. They can be grown year round without any dormancy, but turions are formed if the temperatures drop below 64 degrees F (18 degrees C).