Seeds of the White Water Lily occur in Interglacial beds and recent alluvium. It is found in the Arctic and North Temperate Zone in Arctic Europe, N. Africa, N. and W. Asia to Kashmir, and it is found in North America. This plant is absent from Devon, the Isle of Wight, N. Hants, Essex, W. Gloucs, Monmouth, Hereford, Pembroke, Montgomery, Denbigh, N.W. Yorks, Durham, S. Northumberland, Cheviotland, Isle of Man, occurring only in E. Lowlands in Edinburgh, Linlithgow, not in Stirling, Banff, Mid Ebudes, Caithness, and Orkneys, and up to 1000 ft. in the Lake district. It is found in Ireland.

The White Water Lily is found in similar habitats to the Yellow Water Lily, but whilst the latter is often found in rivers, as well as ponds and lakes, the former is much more common in still waters. It has doubtless been planted here and there on account of its choice beauty, but in most localities is native. With the Yellow Water Lily, though they seldom grow intermixed, it forms a striking contrast.

Aquatic like the Yellow Water Lily it has much the same habit. It has too the same habit of opening and expanding its flowers, expanding at 7 a.m. or in the middle of the day, and letting them rest on the surface closed up about 4 p.m. or in the evening. The leaves are smaller, longer, incumbent or overlapping at the base, and less heart-shaped; 5-10 in. across; the stomata, contrary to the usual rule in terrestrial types, are on the upper surface.

The flower has a double appearance, having a lance-shaped outline, the parts spirally arranged, the sepals, petals, and stamens passing into each other. The ovary contains many ovules, and the stigma lies above it. The embryo is small, the cotyledons remaining in the seed when the latter germinates. The seeds are heart-shaped, smooth, shiny, grey, and embedded in a slimy material after the capsule rots. There is a glandular pore at the base of the petals, and the stalkless rays of the stigma also extend beyond the margin.

This plant lifts its flowers above the surface about 3-4 in. It flowers from July to August. The White Water Lily is a herbaceous perennial.

The carpels, which are embedded in a thick receptacle, are arranged in a radiate manner. The anthers open as soon as the flower unfolds, or the next day. As they stand above the pistil and bend over it the pollen falls upon the stigma, and when no insects visit them the plant is self-pollinated. The flowers are sweet-scented, and a honey-like liquid is produced by the stigma. There is no nectary. Owing to the aquatic habit, creeping insects cannot enter the flower. It is pollinated by beetles of the genus Cetonia and by Glaphyridae. The stamens are inserted on the ovary.

The fruit of the White Water Lily is dispersed both by water and by its own agency. After the expansion of the flower at the surface it recoils to the bottom, allowing the seed to germinate in the mud, and so is dispersed much like seeds of Vallisneria. The carpels possess air-cells facilitating the floating of the seeds. The capsules are edible.

The plant is a Hydrophyte and aquatic, helping to form a certain type of water association - the floating-leaf association.

The beetles that feed upon it are Donacia, menyanthidis, the moths Hydrocampa potamogeti and H. nymphaeata, and the Homopteron Rhophalosiphina nympheae.

The name Castalia is that of a sacred fountain on Mount Parnassus, and alba means white, in allusion to the flowers.

The English names are Alau, Bobbins, Cambie-leaf, Candock, Can-leaves, Flatter-dock, Water Lily, Nenuphar, Water Bells, Water Blob, Water-can, Water Socks, Water Rose. In reference to the name Candock it is called Water-can at Tamworth in allusion to the half-unfolded leaves floating on the water, which are thought to resemble cans. The leaf surface close to the stalks is raised, and the surface is generally convex, so that raindrops collecting run off at the margin, especially as the surface is waxy, which assists transpiration. The underside is purple, due to the presence of anthocyan, which turns the light rays into heat.

A Typical Floating Leaf Association