Kiwi fruit belongs to the Actinidia genus, a climbing vine which is trained to a trellis when cultivated. There are some fifty species in this genus, with a wide variety of fruit. Actinidia can have yellow, orange or green flesh, and smooth or furry skin.
The New Zealanders obtained larger fruit through selection. The most familiar, the green-fleshed kiwi fruit named Hayward after its inventor, was developed in 1928. It has become virtually synonymous with the green kiwi, even though other green-fleshed varieties exist, and clearly dominate the international market. Professionals also began developing yellow-fleshed kiwi fruit, especially in China. During the first decade of the 21st century, the New Zealand variety Zespri Gold kiwifruit began to mark out a place for itself. Its brown skin is almost smooth and its golden-yellow flesh has a slightly acidic taste.
The kiwaï (Actinidia arguta) is another species of Actinidia. It is the size of a cherry tomato and can be eaten without being peeled. Hardy kiwis (Actinidia kolomikta) withstand cold winter weather, down to minus 25°C, whereas other kiwi fruit cannot tolerate temperatures below minus 12°C.
Once picked, kiwi fruit can be stored in a cool, dry place for eight weeks. They can keep for four to six months at temperatures below 0°C. In New Zealand, the fruit is harvested in May and imported during the summer. In Europe, harvesting takes place mainly in November. Since kiwi fruit is cultivated in both hemispheres, the market is supplied continually.