The Alure of
Aponogeton distachyos

by Alberto Grossi, Bondeno, Ferrara, Italy
Click images to enlarge
When I realized that the big plastic pot I had just bought had no holes in the bottom, I thought to use it for an aquatic plant. What to choose? It had to thrive in little water and to survive the frost in winter (where I live in winter we experience -13°C [9°F] at night). I went to a garden center and fell for a white flower floating on the surface of a little pond; I smelled its delightful vanilla fragrance and I had to purchase it. It was Aponogeton distachyos, the water hawthorn or Cape hawthorn. Once at home I filled a third of the pot with common soil. I put the plant in the centre and filled it with water. After a few weeks a new inflorescence appeared.


Plate from Favourite Flowers of Garden and Greenhouse,
Volume IV, 1897
Aponogeton is the only genus in the Aponogetonaceae and all its members are aquatic. They live in streams and ponds in the tropics of Africa, Asia and Australia and in South Africa. The question about the origin of the word for the genus is debated. Apon may come from a Celtic word for water and geton from the Greek geitoneo, meaning "by". In a book published in 1828, dealing with etymology of words (Dizionario tecnico-etimologico-filologico, by Marco Aurelio Marchi) I found a reference to Aponium, the ancient name of Abano Terme (Italy), a city famous for its thermal water. Dís, two, and stáchys, spike, both come from Greek to name the inflorescence compound of two spikes. The flowers lack the classic calyx and corolla; ovary and stamens originate from the base of a little scale. The leaves are about 20 cm (8") long and 6 cm (2") wide, oblong, green on the upper surface with bronze dots, reddish on the lower, and float. The long stalk comes from a hairy black rhizome, about 6 cm (2") in size.
For me the flowers start at the very beginning of March and go on to frost in December, with a rest in the hottest months. After the work of bees and other insects the inflorescence become greenish, inflated and then scatter the seeds that soon germinate, reaching flowering size after just one year under ideal conditions. You can multiply Aponogeton by dividing the clumps of rhizomes, too.   
There are three cultivars: A.d. 'Aldenhamensis' grows bigger inflorescences and purple suffused leaves; A.d. 'Lagrangei' produces both violet bracts and lower surface of the leaves; A.d. 'Roseus' displays pink inflorescences.

A. distachyos L. f. (also spelled A. distachyon or A. distachyum or A. distachyus) occurs naturally in the winter rainfall areas of South Africa where the ponds dry up in summer. There it sprouts in autumn with the first rains. It is known in the vernacular of Afrikaans as waterblommetjie (water-flower) and waterunintjie (water-onion). It was introduced to Europe at the Royal Botanic Gardens, Kew, United Kingdom, in 1788 and since then spread as an ornamental plant all around the world, soon becoming a weed (pond-weed) in some locations. In South Africa two other very similar species grow: A. angustifolius Aiton and A. junceus Lehm. ex Schltdl. Carl Thunberg (1743-1828), the Swedish Botanist who explored that country around 1770, states that roasted rhizomes were eaten by indigenes. After two centuries of cultivation, A. distachyos has become a commercial crop and the inflorescences used in the recipe for waterblommetjie bredie (stew). 

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