The fountain that heads the Main Walk at Cambridge University Botanic Garden was designed by cutler David Mellor and was inspired by the giant pads of Victoria. This genus has never been grown at the Botanic Garden and recently it was felt the time had come to remedy this situation.

This led to the redevelopment of one of the houses in the Glasshouse Range with a 12,000-gallon tank as a waterlily pool and the construction of a tank in the outside bays. Plants of Victoria cruziana were kindly donated by the Royal Botanic Gardens at both Kew and Edinburgh. The opening of the Tropical Wetlands display in Cambridge on 18 May 2013 coincided with the inaugural Festival of Plants, an event to show-off Cambridge University Botanic Garden and the scientific work of the Garden, the University Department of Plant Sciences and the Sainsbury Laboratory Cambridge.

In May and June, the waterlily produced a succession of enormous, ferociously spined lilypads up to 1.5 m in diameter and each with an upturned, notched rim of up to 20 cm. In July, this plant of the Paraguyan waterways began to flower, sending up large waxy flowers one after the other, heavily spined at the base. Each flower lasts just 48 hours. They open in the evening, the white petals unfolding to provide a large platform for scarab beetles (Cyclocephala hardyi), inexpert fliers, which pollinate the plant in the wild. As the flower opens, its temperature increases by up to 20 degrees above the ambient, which encourages the diffusion of an enticing pineapple scent, luring the scarab beetles with the promise of a nutritious, starchy feast held within the large floral chamber.

All night the scarab beetles feast and as they do so scatter pollen from the flower they visited the night before. As dawn breaks, the flower closes up, preventing the beetles escaping. When the flower opens again that evening, the petals become flushed pink and purple and the scent is lost, indicating that the flower no longer has receptive female parts, but is now in an active male phase. As the beetles leave the floral chamber, they are loaded with shed pollen, which they carry to the next white flower in the female phase, and cross-pollination is effected. Fertilised flowers then sink back below the water. Staff expect the Santa Cruz lily to continue to flower until the autumn.

Alex Summers
Head of Glasshouses, Cambridge University Botanic Garden