September 2, 2017
Manchu Tubergourd (Thladiantha dubia)
Thladiantha dubia (Manchu Tubergourd, Goldencreeper or Wild potato) this is perennial climber up to 6 m long (frost-resistant to zone 5/6) native to China and Korea. It survives all winters (even very hard) without mulching in zone 6b. Very rarely cultivated in Europe or America and very ornamental - numerous golden-yellow flowers and red fruits. It creates round or oblong smooth yellow tubers about 2-8cm (1-3 inch) long (which are reportedly edible but I advise to be careful) and tasty red fruits that resemble the fruits of the passionfruit in structure. They have hard hairy red skin and juicy orange flesh with about 40-100 small black seeds inside. There are the informations in many sources on their suitability for consumption. In my experience, I can say that they are very delicious, something aromatic and very sweet, but edible in the raw state only in small quantities, as they irritate the throat while eating (like eating mild chili pepper) - probably due to containing calcium oxalate raffin. But long (2-3 hours) cooked fruit pulp (without seeds) loses its irritating properties and is very tasty, even in large quantities.
Growing: It can be propagated both from tubers and seeds. The seeds need be sown on the surface in light place in pots with well drained soil, and kept moist. The fungicide can help. Later, after last frosts, the young plants can be replanted outside. Climbers planted in the garden often move to neighboring areas (the old bulbs are dying, and the new bulbs are created in distance to them) - hence the plant makes the impression of a wanderer - grows from another place every year and can cover very large area within a few years. Dioecious plant. Our insects do not visit its flowers, because there is a fat oil inside, not a nectar. In nature the flowers are pollinated by small Asiatic bees which belongs to genus Ctenoplectra. To creating fruits in Europe or America (where lacks these bees) you need to pollinate flowers by hand. Female plants also form small, seedless fruits without pollinating.
Above: the small, seedless fruits which grew without pollination
Down: fertile, full developed fruits
Mature fruits after harvest (they should be stored yet by 2-3 weeks to they become overripe, before removing of seeds)
The cutted fruit (the coin on the photo is size about 2,5cm = 1 inch)
There are numerous other species of Thladiantha in Asia. If you have available seeds or tubers of any of them please write to me.
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