The Giant Amazonian Water Lily at Oxford

A magnificent giant and its historic place at the University of Oxford Botanic Garden

By Oxford Botanic Garden and Arboretum

Glasshouses in the Autumn (2018)Oxford Botanic Garden and Arboretum

Glasshouses at Oxford Botanic Garden

There are seven display Glasshouses at Oxford Botanic Garden creating a range of climatic conditions, from tropical jungle and oozing swamp to desert and alpine environments. 

Buddha's hand citron, Citrus medica var. sarcodactylis (2019)Oxford Botanic Garden and Arboretum

The first greenhouse was built at the Botanic Garden more than 300 years ago. It was a temperate conservatory, which resembled an orangery or grand stable. Its purpose was to house tender and exotic plants, such as citrus (like this 'Buddha's hand'), during the winter.

Lily House, Botanic Garden, Oxford (1859) by Roger FentonThe J. Paul Getty Museum

In 1851, Charles Daubeny, the Professor of Botany at the University of Oxford at the time, had the Water Lily House (shown here in 1859) constructed at Oxford Botanic Garden after an inspirational visit to Chatsworth House, in Derbyshire, where head gardener Joseph Paxton had grown Victoria amazonica successfully for the first time in Britain. 

V. amazonica was grown in the new specially designed glasshouse pond, and visitors were charged a shilling to see it. Today visitors can still enjoy these magnificent water lilies in the original pond built by Daubeny.

Native to tropical South America, V. amazonica is probably most famous for its large circular leaves, which span over 2.5 m across and can hold the weight of a small child. 

Under the leaf of Victoria cruzianaOxford Botanic Garden and Arboretum

Anchored to the muddy floor of the river bed, the leaves rise from the depths as spiny buds which then expand rapidly; in a single season a plant can produce up to 50 leaves, which float on the surface by virtue of little pockets of air between the ribs.

Maintaining Victoria cruziana (2019)Oxford Botanic Garden and Arboretum

These plants produce at least one leaf per week in the height of summer. The botanical horticulturalists at Oxford Botanic Garden have to work hard to keep it from taking over the water lily pond. 

Victoria amazonica, a magnificent giant (2018)Oxford Botanic Garden and Arboretum

Fascinating Flowers

The leaves of this plant may be impressive, but their nocturnal flowers are equally so. They do not last long though, perishing after just 48 hours or so, and each plant produces just one flower at a time.     

Victoria amazonica flowering (2018)Oxford Botanic Garden and Arboretum

The flowers of V. amazonica change dramatically over the course of 48 hours. Upon opening, the flower is white and produces a sweet pineapple-like scent. Moreover, thermochemical reactions generate heat within the flower and it becomes 11◦c warmer than their surroundings. This combination of colour, heat and scent is irresistible to scarab beetles.

Timelapse footage of Victoria amazonica (2018)Oxford Botanic Garden and Arboretum

The flowers are also protogynous: this means that upon opening, the female parts are receptive, and later the male parts mature, avoiding self-fertilisation. Teeming within the flowers, the beetles spread pollen brought from other water lilies over the receptive female parts, and cross-fertilisation takes place. To ensure that the beetles become coated in the plant’s own pollen, the water lily has another trick up its sleeve…

Bud of Victoria amazonicaOxford Botanic Garden and Arboretum

By nightfall, the flower temperature drops, the pineapple-like scent disappears, and the petals close inwards, trapping the beetles inside. Sixteen hours after opening, the beetles become showered with the water lily’s own pollen. Finally, the petals start to open, and release the captive beetles. Now the flowers turn pink, and are no longer attractive to incoming beetles.

Victoria amazonica, pollination process (2018)Oxford Botanic Garden and Arboretum

Free to leave, the beetles fly off in search of a new white flower and the process is repeated. With the job done, the flower closes up and sinks back below the surface.

Maintaining a giantOxford Botanic Garden and Arboretum

Cultivation

Victoria amazonica is more difficult to cultivate than its close relative V. cruziana, which is grown at Oxford Botanic Garden more regularly. The pollinating beetles are not native to the UK so our skilled horticulturalists must undertake the pollination themselves. In the summer of 2018 V. amazonica successfully flowered in the Water Lily House once more, alongside V. cruziana.  

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University of Oxford Botanic Garden and Arboretum

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