File:Water lily (Nymphaea alba), Woodfry's Farm - geograph.org.uk - 1408002.jpg

English: Water lily (Nymphaea alba), Woodfry's Farm The two common wild water lilies are easily identified when in flower: Nymphaea alba bears white flowers in July and August and has rounded leaves, while Nuphar lutea, from June to August, bears yellow flowers which are much smaller, and has oval leaves. Both have massive underground stems or rhizomes by which they are anchored to the bottom of the lakes, ponds or slow-moving rivers in which they grow. Leaves and flowers grow up from the bottom and float on the surface, because their stems are spongy and full of air spaces. Although the leaves are large, they do not shut out enough sunlight to harm other pond life. At night night the petals collapse and the flower may sink below the surface of the water to emerge again next morning. The rooting stems are sometimes eaten in northern Europe, and in the past were used as a cure for baldness.