Kiwifruit, Chinese gooseberry (Actinidia deliciosa)
ACTINIDIACEAE,Actinidia Family
Back in the 1960s--if you were living, that is--you would not have found (Actinidia deliciosa, formerly A. chinensis) at your grocery store. This has been a fairly recent arrival from eastern Asia but via Australia and New Zealand. An enterprising business woman invented the name kiwifruit and then imported these to U.S. markets with an advertising blitz that ensured her success. Now it is cultivated closer to home, and has become a popular regular in our stores. Its flavor is similar to a strawberry, and its bright green color certainly is a selling point for this sweet fruit.
Kiwifruit is a dioecious vine, hence only the female plants produce fruits, but you must have males, i.e., pollen, to set fruits. The fruit is a berry with up to 1400 tiny black seeds; the exocarp consists of a hairy golden-brown surface, which is easily removed to reveal the sweet green pulp throughout the fruit. Number of seeds is critical, because that feature has a bearing on fruit size.
Kiwifruits are commercially harvested unripe, so that the fruit can be shipped hard to avoid bruising and rotting. Often in stores the fruit is still hard, but it can turn soft within a day or so, as a response to the formation of ethylene, a natural gas of fruit ripening, and temperature is also a factor. Enclosing fruits like these, avocados, and bananas in a bag often causes ethylene concentrations to rise, thereby accelerating the softening process, wherein cell walls become thinner and starches are converted into sugars.
High interest in A. delisiosa has also sparked horticultural interest in species that are more tolerant of colder climates. These more hardy types include A. arguta, the bower actinidia, and A. kolomikta, both which can tolerate winter temperatures below -20 degrees F. One problem, though, is that plants must grow a number of years before they start to produce fruits.