Actinidia is a genus of woody, mostly dioecious plants in the family Actinidiaceae, comprising shrubs and vigorous climbing vines. POWO recognises 56 accepted species, while broader treatments cited in Wikipedia put the range at roughly 40–60 species. The genus is the type genus of its family and was formally described by John Lindley in 1836.
Plants in the genus carry alternate, simple leaves with dentated margins and bear flowers that are usually solitary or borne in the leaf axils — typically white with five small petals. The genus name comes from the Ancient Greek ἀκτῑ́ς, meaning "ray," in reference to the conspicuously rayed styles of the flowers. The fruit is a large berry containing numerous small seeds, and the seed-rich, edible fruit of several species — most famously Actinidia chinensis — is the basis of the worldwide kiwifruit industry.
Habit varies widely across the genus. Some species are modest shrubs reaching about 6 m (20 ft), while the most vigorous vines can scramble 30 m (100 ft) into the canopies of host trees. Native to temperate eastern Asia, Actinidia spans the Himalaya through China, Korea, Japan, Taiwan and Indochina, and reaches north into the Russian Far East. Within that range, plants are characteristically found in the lower storey of forests, along stream beds, and at forest margins, often at elevations between 700 and 3,600 m.
Several species are cultivated for fruit, ornament, or both. Actinidia chinensis (including var. deliciosa) supplies the familiar kiwifruit of commerce; Actinidia arguta and Actinidia kolomikta are popular as hardy kiwis in cool-temperate gardens; and Actinidia polygama (silver vine) is notable for the strong stimulant response it provokes in domestic cats, comparable to catnip. Hardiness is striking — Actinidia kolomikta tolerates winter temperatures to roughly −40 °C, and Plants For A Future reports some cultivars surviving dormancy at down to −50 °C — which has helped extend the genus's cultivated range far beyond its native distribution.
Etymology
The genus name Actinidia is derived from the Ancient Greek ἀκτῑ́ς (aktís), meaning "ray," a reference to the conspicuously rayed styles of the flowers. John Lindley published the genus in 1836 in the second edition of his Introduction to the Natural System of Botany, and the name has remained in use unchanged since.
Distribution
Actinidia is native to temperate eastern Asia. POWO summarises the range as "Himalaya to Russian Far East and Malesia," extending across Assam, the East and West Himalaya, Nepal, Myanmar, much of China (including Tibet, Inner Mongolia, Hainan and the southern and central provinces), Taiwan, Japan and the Nansei-shoto, Korea, the Kuril Islands, Sakhalin, Khabarovsk and Primorye in the Russian Far East, and south through Laos, Cambodia, Vietnam, Thailand, Malaya, Borneo and Sumatera. The genus has been introduced and naturalised in parts of Europe (Austria, Czechia-Slovakia, Germany, Italy, Sweden), Uzbekistan, both islands of New Zealand, Ontario in Canada, and across much of the central and eastern United States — including Arkansas, Connecticut, Georgia, Maine, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee and Virginia.
Ecology
Actinidia species are perennial climbing vines (with some shrub forms) characteristic of the lower storey of forests, stream banks, and forest margins. In their native East Asian range they grow in woodland, mountain forests, thickets, and other moist places, typically at elevations between 700 and 3,600 m. Habit varies from compact shrubs to about 6 m tall up to vigorous vines that ascend 30 m into tree canopies. Most species are dioecious, so wild populations and orchards alike depend on the presence of both male and female plants for fruit set.
Cultivation
Across the genus, Actinidia prefers a sound, loamy, neutral soil but tolerates acid and moderately alkaline conditions. Plants do best in semi-shade but produce more fruit in full sun, and they appreciate a sheltered position protected from strong winds. Hardiness varies sharply by species: Actinidia kolomikta is reported tolerant to about −40 °C, and some cultivars within the genus survive dormant-season temperatures as low as −50 °C, giving cool-temperate growers access to fruiting kiwi vines well outside the genus's native climate.
Propagation
Actinidia can be raised from seed or from cuttings. Seeds benefit from cold stratification and are typically sown in spring under glass, germinating within two to three months at around 10 °C. Vegetative propagation is more reliable for fruiting selections: softwood cuttings taken in spring strike well, half-ripe wood cuttings taken in July or August are reported to achieve very high success rates, and ripe-wood cuttings can be taken in October or November.
History
Actinidia chinensis — the source of the kiwifruit — was first recorded in 12th-century China during the Song dynasty, where it was used in folk medicine rather than as a cultivated crop. Plants were introduced from China to New Zealand in the early 20th century, and the fruit reached a wider Western audience during World War II when British and American servicemen stationed in New Zealand encountered it. New Zealand growers began exporting the fruit — then known in the trade as Chinese gooseberry — to Great Britain and Australia from 1953 and to California from 1959. The name "kiwifruit" was coined in 1959 by the New Zealand exporter Turners & Growers, on the advice of US client Norman Sondag, partly to sidestep American quarantine concerns associated with the "Chinese" label. Italy became the world's leading producer by 1989, and as of 2023 China accounts for 55% of global production.
Cultural Uses
The fruits of Actinidia species are edible across the genus and are notably rich in vitamin C; they are eaten fresh, cooked or dried, and the sap of some species can be tapped in spring. Commercially, two main types dominate: Actinidia chinensis var. deliciosa (fuzzy green kiwifruit) and Actinidia chinensis var. chinensis (golden and red kiwifruit cultivars). The crop is now grown worldwide, with China the largest producer (55% of world output in 2023), followed historically by New Zealand and Italy. Beyond fruit, Actinidia polygama (silver vine) is widely known for producing a strong stimulant response in domestic cats, comparable to that of catnip.
Taxonomy Notes
The genus Actinidia Lindl. was published by John Lindley in 1836 (Intr. Nat. Syst. Bot., ed. 2: 439) and is the type genus of family Actinidiaceae. POWO currently lists 56 accepted species, while Wikipedia cites a broader range of about 40–60 species; GBIF records 141 descendant taxa under the genus once subspecific names and synonyms are included. The kiwifruit of commerce is now treated as Actinidia chinensis, with the former species A. deliciosa demoted to A. chinensis var. deliciosa alongside var. chinensis (golden/red kiwifruit).
