Metaplexis japonica
Common Name: gaga-imo 
Type: Vine
Family: Apocynaceae
Native Range: Asia
Zone: 6 to 8
Height: 15.00 to 25.00 feet
Spread: 3.00 to 6.00 feet
Bloom Time: June to August
Bloom Description: Purple-white
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Vegetable
Flower: Showy
Fruit: Showy
Tolerate: Drought

Culture

Easily grown in average, medium moisture, well-drained soils in full sun to part shade. Generally tolerates periods of drought.

Noteworthy Characteristics

Metaplexis japonica, commonly known as rough potato, is an herbaceous, pubescent, deciduous, twining vine with annual stems and rhizomatous perennial roots. It typically grows to 25’ high on fast-growing annual stems. It is native to thickets, forest margins, grassland and streambanks in China, Manchuria, Japan, and Korea. It is generally considered to be winter hardy to USDA Zone 6b, however plants were discovered spreading through cornfields near Ames, Iowa in 1958 (USDA Zone 5), presumably introduced unintentionally in that area in the course of a research project conducted during World War II on the subject of the feasibility of using twining milkweeds as a source of fiber. Vine stems are densely pubescent. Ovate leaf blades (to 4” long by 2” wide) with cordate bases are deep green adaxially (above) and whitish-green abaxially (underneath). Pale purple to white, star-shaped, 5-petaled flowers bloom in axillary racemes (13-20 flowers per raceme) from late June to August. Flowers are followed by elliptic seed pods which split open vertically when ripe to release numerous silky-haired seeds (reminiscent of milkweed) which are easily carried by wind to other locations.

Stems and roots have been used for certain medicinal purposes including treatment of traumatic injury, snake bites, and infantile malnutrition.

Genus name comes from the Greek word meta meaning after or beyond and the Latin word plexus meaning twining.

Specific epithet is in reference to the native territory of this plant which includes Japan.

Problems

No serious insect or disease problems.

Garden Uses

Rough potato is an Asiatic vegetable plant featuring edible young leaves (raw or cooked), fruits (raw or pickled) and roots (cooked). Plants are cultivated as a vegetable in China. Infrequently grown for ornamental or culinary purposes in North America. Interesting twining vine with ornamentally attractive flowers.