菊薯 ju shu

Polymnia sonchifolia Poeppig, Nov. Gen. Sp. Pl. 3: 47. 1843.

Herbs, perennial, 1-3 m tall. Stems cylindric and hollow; underground part irregularly branched, often producing spindle-shaped tubers 100-200 mm and 30-80 mm in diam. Lower leaves broadly ovate and hastate or subhastate, connate and auriculate at base; upper leaves ovate-lanceolate, without lobes and hastate base; upper and lower surfaces densely pubescent. Synflorescence terminal, composed of 1-5 branches, each one with 3 capitula; peduncles densely pilose; phyllaries 5, 1-seriate, ovate. Corollas yellow to bright orange; ray florets female, 2- or 3-toothed, depending on clone, lamina ca. 12 × 7 mm; disk florets male, ca. 7 mm. Immature achenes purple, turning dark brown or black at maturity. Fl. Jun-Sep.

Cultivated in Fujian, Guizhou, Hainan, Hebei, Hubei, Hunan, Shandong, Taiwan, Yunnan, and Zhejiang [native to South America (Bolivia, Colombia, Ecuador, Peru)].

Known as Yacón in South America, this species is an ancient crop of the Andes with tuberous roots that can be eaten raw or cooked.