This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Fruits of the Yellow Water Lily are known from deposits of Pre-glacial, Interglacial, Neolithic, and Postglacial age. The Warm Temperate Zone is the limit of its distribution in Europe, Temperate Asia, and North America. It is absent from E. Cornwall, N. Devon, Isle of Wight, Radnor, Montgomery, Mid Lancs, Isle of Man, Peebles, Selkirk, Linlithgow, Stirling, Banff, Easterness, Westerness, Cantire, Mid and E. Ebudes, in W. Ross, E. Sutherland. It is found at 1000 ft. in Yorks, and occurs in Ireland.
In most parts of the British Isles the Yellow Water Lily graces most pools and wide stretches of open still water. It is entirely aquatic and so a Hydrophyte, associated with Pondweeds, Arrowhead, Flowering Rush, and numerous other common water plants, such as Amphibious Knotgrass, Great Yellow Cress, and Water Crowfoot. Its broad leaves afford a resting-place in many a secluded pool for minute shell-fish, and shade the fish from the rays of the sun. They are of two kinds, one floating and thick, the other submerged and membranous.
Photo. J. H. Crabtree - Yellow Water Lily (Nymphaea Lutea, L.), Showing Reed Swamp And Floating-leaf Association
As an aquatic this plant has floating leaves, with slender, long, ropelike rhizomes or stems, which are in reality little more than branches. The flowers rise up above the level of the water, and open during the sunshine and the daytime, and close at night and are submerged. The parts, which are numerous and merge into each other - e.g. petals, sepals, stamens - are spirally arranged.
The shape of the carpellary organs, like a brandy bottle, has provided an English name for this plant, whose stigma has numerous rays which do not extend to the margin. The flowers smell like brandy. The sepals and petals stand upon a fleshy disk surrounding the ovary with many ovules. The petals are small, the stamens inserted below the ovary. There is a nectary.
The Yellow Water Lily is aquatic, and the flowers rise above the water level but 2-3 in. during the day. It flowers from June to August, and is a herbaceous perennial.
The 5-6 yellow sepals have taken on the function of petals, the outer or underside secreting honey between them and the petals. The pistil is large and the stamens are numerous, but pollination by insects is accidental. The flowers are scented. The stigma matures first, then the anthers, commencing outwards.
The visitors are beetles, Meligethes, various flies, and other beetles, Onesia (Muscidae), Donacia dentata (Chrysomelidae). The pollen-grains are large, rough, elliptical.
The fruits are dispersed by the agency of water and the plant's own methods. After the flower has expanded at the surface it retires to the bottom to allow the seed to germinate when mature, in the mud at the bottom, being thus dispersed by an automatic, almost psychic, motion of the plant itself (cf. Vallisneria in some respects). See also Nymphaea (Castalia) alba. It is a Hydrophyte and aquatic, growing in the floating-leaf association.
No fungi attack it. Galeruca nymphaea, Donacia crassipes (beetles), and the moth Hydrocampa potamogeti visit it.
The name Nymphaea was given by Theophrastus, being from the Greek nympha, water nymph, lutea meaning yellow.
The English names are Blob, Bobbins, Brandy-bottle, Butter Churn, Butter-pumps, Cambie-leaf, Candock, Churn, Clot, Clote-leaf, Water Colt's-foot, Flatter-clock, Yellow or Water Lily, Lily-can, Nenuphar, Water Blob, Water-can, Water Rose.
The name Brandy-bottle alludes to the odour of the flower, or the shape of the ovary more probably, so also Butter Churn; and Candock is given from its broad leaves and the shape of the ovary, like a silver can or flagon.
The Water Lily was considered inimical to sorcery, and in the Rhine district used with a certain formula. Pliny says it was used as an antidote for a love-philtre. The smoke of it burnt in a house was said to drive out crickets, and cockroaches also are killed by partaking of the roots bruised and rubbed in milk; but pigs are fond of the leaves and the root, though other animals will not touch it.
Essential Specific Characters:16. Nymphaea lutea, L. - Leaves submerged, wavy, transparent, floating leaves coriaceous, flower yellow, globose, sepals 5, stigmas rayed, not reaching the margin, petals numerous, anthers hypogynous, linear, the fruit a berry.