and moisture conditions. The optimal growing temperature range is 18- 25 °C. Reproductive characteristics Yacón plants produce small, inconspicuous flowers at the end of the growing season. The timing of flowering strongly depends on the environmental conditions. If environmental conditions are favourable, flowering begins 6–7 months after planting and peaks about two months later. The yellow to orange coloured flower head is a pseudanthium (i.e. one apparent flower head is in reality composed of several florets). Each flower head is bisexual, uniting female and male florets in one pseudanthium. The yellow or orange ray florets are female and up to 12 mm long, while the yellow-brown disc florets are male and about 7 mm long. Seeds are stored inside achenes, which measure on average 2.2 mm - 3.7 mm and are dark brown in colour. In general, seed production is rather low; some ecotypes do not produce any seeds at all, due to pollen sterility. Plants produced from seed take longer to mature than do those grown from the tubers or rhizomes. Cultivation Yacón can easily be grown in gardens in climates with only light freezes. It grows well in Kathmandu, Nepal, southern Australia (including Tasmania) and in New Zealand, where the climate is mild and the growing season long. The plant was introduced to Japan in the 1980s, and from there its cultivation spread to other Asian countries, notably South Korea, China, and the Philippines, and is now widely available in markets in those countries. Yacón has also recently been introduced into farmers' markets and natural food stores in the United States and has been available from niche online health food stores in the United Kingdom since 2007. Yacón is also grown on the Atherton tablelands in Queensland. The plant can be grown using either stem cuttings or the purple rhizomes at the base of the stalks. It will not reproduce from the tubers, which, when unharvested, rot in the ground, providing fertilizer for later crops. Outside of its traditional cultivation range, yacon is planted in a well-dug bed in early spring, near the time of the last expected frost. While aerial parts are damaged by freezing temperatures, the tubers are not harmed unless they freeze solid. Yacón is a vigorous grower, much like Jerusalem artichokes. The plants grow best with fertilizer. After the first few freezes, the tops will die and the tuberous storage roots are ready for