The crowning jewels of any decorative pond are water-lilies - found all over the world, growing in lakes and ponds. The leaves float on the water, while the flowers stick only a few centimetres above the surface. Botanical gardens, palace grounds, and artificial ponds on private property proudly display water lilies as essential parts of their waterscapes.Water lilies and lotus are immensely edible, starting with their underground parts, rhizomes or tubers buried in the mud under the pond. These are edible and an important part of Asian cuisine. You can buy these dried, canned or pickled in Asian markets or harvest them from the mud below your garden pond. The tubers are sausage-shaped, white, and starchy, with air chambers inside allowing the plant tissues to breath under water. Slice them and add them to salads, fried Asian dishes, or other items. The tubers are quite nutritious, rich in fibre, vitamins and minerals. They have a bit of a nutty taste that many people find appealing. Young leaves and unopen flower buds are also edible, useful in salads or as cooked vegetables. The seeds are high in protein. You can pop them like popcorn or grind them into flour.It might seem like a waste to eat these plants instead of enjoying the beauty of some of the most spectacular flowers on Earth. But any plant can become too plentiful and too numerous, requiring thinning so that the remaining ones can thrive, so pruning time is a good time to strike!There are many species of lily and they come in an assortment of colours: mostly white, yellow, or pink but occasionally blue or purple. Largest is the giant water-lily native to the Amazon, named in honor of Queen Victoria. The scientific name is sometimes given as Victoria regina or Victoria regia, but is more correctly Victoria amazonica. It has round leaves up to 4 metres across and enormous flowers up to 40 cm in diameter. Fit for a queen, to be sure.Very similar to the water lilly is the lotus (Nuphar). The lotus is sacred to the Hindus and displayed in much Indian artwork. Lotus plants are very similar to those of Nymphaea and long thought to be closely related, but recent molecular studies suggest that the similarities are superficial. Nuphar has a distinctive seed-pod, shaped like an apple pie with holes in the top. You will know this one from dried flower arrangements. Visually, the main difference between a lotus and a lily is that the lotus leaves sit up to a metre above the water while the water lily leaves sit on the water. Queen Victoria’s water-lily might be a wee bit large for your own backyard water garden, but there are thousands of species available that are smaller than the Queen Victoria and go right down to container size. There are several aquatic nurseries in Australia selling lilies and lotus. The tropical species are suitable for the north, but those native to cooler climates are more appropriate for gardens in Victoria or Tasmania.Image: Dr J Beller/Shutterstock