Victoria amazonica has very large leaves (
lamina; commonly called "pads" or "lily pads"), up to in diameter, that float on the water's surface on a submerged stalk (
petiole), in length, rivaling the length of the
green anaconda, a snake local to its habitat. These leaves are enormously buoyant if the weight is distributed evenly over the entire surface of the leaf (as by a piece of plywood, which should be of neutral buoyancy). In 1896 a
V. amazonica leaf at
Tower Grove Park, Saint Louis,
Missouri bore the "unprecedented" weight of . However, in 1867 William Sowerby of
Regents Park Botanic Garden in
London placed on a leaf only in diameter. One leaf of a specimen grown in
Ghent,
Belgium bore a load of It is the second-largest waterlily in the world. The leaves and flowers spring forth from a perennial
rhizome up to thick. The rhizome can live at least 7 years, but often much shorter (frequently annual) due to seasonal fluctuations in water level. Because of the leaf's air spaces, the leaf is surprisingly light. Laurent Saint-Cricq (pen name "Paul Marcoy") found a leaf diameter weighed only .
V. amazonica is native to the still and slow-moving waters of the
Amazon River basin and some other drainage basins of northern South America, growing in water up to 5.25 m deep. exceeded in mass only by members of the genus
Rafflesia. All of the flowers of one particular plant will, on a given evening, all be in the female phase or all in the male phase, so that pollination must be by a different individual, precluding self-pollination. The stem and underside of the leaves are coated with many small
spines to defend itself from fish and other
herbivores that dwell underwater, although they can also play an offensive role in crushing rival plants in the vicinity as the lily unfolds as it aggressively seeks and hogs sunlight, depriving other plants directly beneath its leaves of such vital resource and significantly darkening the waters below. Younger giant water lilies are even known to swing their spiny stalks and buds around as they grow to forcibly make space for themselves. == Ecology ==