Actinidia arguta

Actinidia arguta, the hardy kiwi, is a perennial vine native to Japan, Korea, Northern China, and Russian Far East. It produces a small kiwifruit without the hair-like fiber covering the outside, unlike most other species of the genus. The fruit is referred to as hardy kiwifruit, kiwi berry, arctic kiwi, baby kiwi, dessert kiwi, grape kiwi, northern kiwi, or cocktail kiwi, and are edible, berry- or grape-sized fruit similar to kiwifruit in taste and appearance, but are green, brownish, or purple with smooth skin, sometimes with a red blush. Often sweeter than the kiwifruit, hardy kiwifruit can be eaten whole and do not need to be peeled. Thin-walled, its exterior is smooth and leathery. Actinidia arguta was first described by Philipp Franz von Siebold and Joseph Gerhard Zuccarini in 1843 as Trochostigma argutum. It was then moved to the genus Actinidia in 1867 by Friedrich Anton Wilhelm Miquel after the invalidly published suggestion by Jules Émile Planchon to move the species. The species consists of three varieties: Actinidia arguta var. giraldii was originally described by Ludwig Diels at the species rank (Actinidia giraldii) in 1905, but was later reduced to a variety of A. arguta in 1972 by Vladimir Nikolaevich Voroschilov. A. arguta var. hypoleuca was originally described at the species rank (Actinidia hypoleuca) by Takenoshin Nakai in 1904, but reduced to a variety of A. arguta in 1980 by Siro Kitamura. Actinidia arguta had been placed in section Leiocarpae and series Lamellatae, but this current infrageneric classification is unsupported. A 2002 study of the nuclear DNA internal transcribed spacer sequence and the plastid matK gene sequence for cladistic analysis revealed the current circumscription of the sections to be polyphyletic, with A. arguta forming a clade with A. melanandra near the base of the phylogenetic tree. The most popular cultivars include 'Ananasnaya', 'Geneva', 'MSU', 'Weiki', 'Jumbo Verde', and 'Rogow'. A commonly sold self-fertile hybrid is the Japanese cultivar 'Issai' (A. arguta × rufa). The fast-growing, climbing vine is very hardy (hence the name hardy kiwi), and is capable of surviving slow temperature drops to -34 °C (-30 °F), although young shoots can be vulnerable to frost in the spring. The vines need a frost-free growing season of about 150 days, but are not damaged by late freezes, provided that temperature changes are sufficiently gradual to allow plants to acclimate. Indeed, a period of winter chill is necessary for successful cultivation. However, rapid freezes kill off buds and split vines. The vines can also be grown in low-chill areas.