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Kiwifruit
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History
Although the kiwifruit is now one of the most popular of all the exotic fruits available in Britain, it was not discovered by Europeans until 1847 and was first introduced into this country in 1900. The kiwifruit plant (Actinidia deliciosa, known as A. chinensis until recently) is native to the Yangtze Valley in China and for many years kiwifruits were called Chinese gooseberries. Another fruit, the starfruit (Averrhoa carambola), is sometimes known by the same name. The name kiwifruit was coined by growers in New Zealand due to the supposed resemblance of the fruit to their national bird, the kiwi.
What does the kiwifruit plant look like?
Actinidia deliciosa is a woody deciduous vine, reaching 9 m in length, with large heart-shaped leaves. Its young shoots and leaves, covered with red hairs, give the plant a very attractive appearance, making it popular as an ornamental climber. The flowers are fragrant and showy, with white petals that become yellow as they age. The plants are dioecious - that is, each plant bears only flowers of one sex, either male or female. Both male and female flowers have a mass of stamens although the female flowers do not produce viable pollen. In commercial plantations one male vine is planted for every eight female vines, and beehives are imported to ensure good pollination.
The fruit and its uses
The kiwifruit itself is egg-shaped and russet-brown in colour with a covering of short stiff hairs. Inside, the flesh is bright green around a white core with fine pale lines radiating fromit. Numerous very small black seeds surround the core. Although the whole of the fruit is edible, it is normally peeled because its surface hairs can irritate the throat. These hairs may also cause a skin reaction.
Usually the fruits are eaten fresh in desserts or salads, but some are canned or frozen (although this causes a loss of flavour). They contain high levels of vitamin C - higher than most citrus fruits - and one fruit can provide the daily recommended intake of this vitamin for an adult. An enzyme, actinidin, in the fruits' flesh, has a meat-tenderising activity. However, the fruit cannot be used in jellies because the enzyme will prevent setting. Kiwifruits can be stored for long periods without deteriorating - up to 9 months at low temperatures. They are ready for eating when the surface yields slightly to the touch. Unripe fruit can be ripened by storing for a short time in a sealed plastic bag with a banana or an apple.
Where are kiwifruit grown?
In New Zealand, kiwifruit is one of the major horticultural crops. It is also grown commercially in the USA, Australia, South Africa and some European countries, including the Channel Islands.
Growing requirements
In Britain, Actinidia deliciosa is often grown as an ornamental climber. To the south of London, it can be grown outside in sheltered sunny sites. The plants are naturally vigorous climbers and should be trained over a trellis or pyramid of stakes. In spring, as the leaf buds begin to grow, old wood should be pruned out to encourage new shoots and fruiting spurs. The vine is susceptible to wind damage. It will not grow well in areas subject to late spring frosts since these damage the flowering wood, but when the plant is dormant, after the leaves have fallen, it can withstand considerably lower temperatures.
Plants should be grown in well-drained deep fertile soil with plenty of water during the summer. As Actinidia is dioecious, both male and female vines must be planted together for pollination prior to fruiting. Fruits can be picked from October onwards after the leaves have fallen. Usually the plant is propagated by budding because the hybrid seedlings show very variable characteristics. Seeds should be sown quickly after removal from the fruit and the seedlings should only be planted out when there is no danger from frost.
Related plants
Other species of Actinidia, such as A. arguta with its red stalks and lustrous oval leaves, are also grown as ornamental or fruiting plants. A. kolomikta has particularly attractive leaves with pink and white tips, and the silver vine (A. polygama) is grown for its young silvery shoots. These species are particularly popular with cats because they contain an oil in their bark and shoots similar to that found in catnip.
Where can kiwifruit plants be seen at Kew?
Plants of Actinidia deliciosa are grown outside near the Flag Pole as well as in the Temperate House. A. kolomiktacan be seen clambering over the walls around the Order Beds.
Additional sources of information
Brickell, C. B. (ed.), 1989. The Royal Horticultural Society Gardeners' Encyclopaedia of Plants and Flowers, Dorling Kindersley
Grigson, J. and Knox, C., 1986. Exotic Fruits and Vegetables, Jonathan Cape
Heal, C. and Allsop, M., 1986. Queer Gear, Century Hutchinson
Jenuwein, H., 1988. Avocado, Banana, Coffee: How to grow useful exotic plants for fun, British Museum (Natural History)
Keesing, J. L. S., 1988. Useful plants. In Kew Gardens Book of Indoor Plants, ed. J. B. Simmons, pp. 186-213, George Philip
Morton, J., 1987. Fruits of Warm Climates, Julia F. Morton
Mossman, K., 1977. The Pip Book, Penguin
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