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.
Note how the flower is raised above the surface of the water, and how the leaves have the margin turned up.
The flowers of the White Water Lily are very beautiful, and the petals being numerous are apparently double, and sweet-smelling. They open at seven o'clock in the morning, and close again, when they lie on the surface, about 4 p.m., or relatively later in each case.
The roots are astringent, and have been used in Ireland and Scot-land as a dye, dark-brown or chestnut in colour. Both flowers and root were once used medicinally, but are not now employed. All animals except pigs refuse it as food.
Essential Specific Characters:17 Castalia alba, Wood. - Leaves orbicular, 2-lobed, entire, flower white, floating, rising above the surface, sepals 4, adnate, green at back, petals numerous, stigma yellow, stigmatic rays 15-20, fruit a berry, globose.