The Waterlilies
Evolutionary History
| The Waterlily family, Nymphaeaceae, is very old and primitive, presently embracing six genera: Nymphaea, Nuphar, Victoria, Barclaya, Ondinea and Euryale. Until recently it also included Brasenia and Cabomba, which are now separated into their own family Cabombaceae. All members of these families have a long fossil history, rhizomes, fruits, seeds, leaves and pollen grains having been discovered in ancient rock formations. Pollen grains from what are believed to have been tropical Nymphaea have been discovered in samples of coal laid-down in Jurassic times. The Sacred Lotus or Nelumbo, was also formerly included in the Nymphaeaceae, but is now assigned to Nelumbonaceae.
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 Fossil evidence suggests that waterlilies are as they were 160 million years ago.
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| This has been recognised in the upper Cretaceous rocks of North America, Greenland and Europe. The non-European Brasenia, or an allied and now extinct form, is also recorded from older Cretaceous rocks in Portugal. Before the Ice Age, members of the Nymphaeaceae, particularly Nymphaea, were known to be widespread from the Arctic to Australia. Fossil evidence suggests that many are still in the very same form that they were over 160 million years ago, having altered only their distribution in response to climatic changes. A living example of this is the tropical species Nymphaea lotus, which enjoys a natural distribution that extends from Egypt in the north through Central and Western Africa to Madagascar in the south, but also occurs in an identical form in thermal springs in Hungary. It is believed that as the climate of Europe altered and became cooler, the populations of N.lotus were pushed back to North Africa, yet a small group remained in the relative warmth of the thermal springs where they have survived until the present day.
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 Nymphaea lotus was pushed back to North Africa during the Ice Age.
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This theory is reinforced by the fact that snails, closely allied to those which are found in the natural habitat of N.lotus in Egypt, are peculiar to these thermal springs too. Thus it is possible to see, that although the habit of growth and blossoms of waterlilies appear to be quite sophisticated, they are in fact very old plants and well down the evolutionary scale, being in company with other garden plants like Berberis, Paeonia and Ranunculus in a group known botanically as the Ranales.
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| The Nymphaea are exclusively herbaceous aquatic plants with either submerged or floating leaves, or both. They normally inhabit still, fresh water in ponds and lakes, and occur in forms that will tolerate a wide range of depths. On occasions, when a pond dries up for a period of time during the summer months, certain species are capable of becoming dormant and resting in the form of a rhizome or tuber. Others will produce an almost terrestrial form with leaves on short petioles that lie flat on damp ground. Adaptation to this latter mode of existence is particularly noticeable with temperate species, such as N.alba, which may be temporarily aground if growing close to the edge of a pond with a variable water level. The ability to transform to a terrestrial mode of life takes place quickly and without much apparent deterioration of the plant.
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Most Nymphaea prefer water that is neutral or slightly alkaline, few tolerating acid conditions and becoming weak and sickly when obliged to do so. In addition, waterlilies will only be discovered growing in water in an open situation with full exposure to the sun. However, in open areas subject to considerable wind and subsequent water turbulence Nuphar will appear where it might be thought that Nymphaea would grow.
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 Temperate species, like the European Nymphaea alba, can readily adapt to varying water levels.
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