3. Helianthus tuberosus Linnaeus, Sp. Pl. 2: 905. 1753.
菊芋 ju yu
Helianthus tomentosus Michaux; H. tuberosus var. subcanescens A. Gray.
Herbs, perennial, 50-200 cm, rhizomatous, producing tubers late in growing season. Stems erect, scabrid-hispid to hirsute, sometimes glaucous. Leaves mostly cauline, opposite or alternate proximally, usually alternate distally; petiole 2-8 cm, often ± winged; blade lanceolate to ovate, 10-23 × 7-15 cm, 3-veined from near base, abaxially puberulent or hirsutulous to tomentulose and gland-dotted or ± scabrid, base broadly to narrowly cuneate, margin entire or serrate. Capitula 3-15; peduncles 1-15 cm; involucres hemispheric, 10-25 × 8-12 mm; phyllaries often dark green, drying nearly black, 22-35, subequal, lanceolate, 8.5-15 × 2-4 mm, abaxially hispidulous or puberulent, gland-dotted, base appressed, margin ciliate, apex ± spreading, sometimes reflexed in fruit, acuminate; paleae 8-9 mm, 3-toothed, apices hairy. Ray florets 10-20; lamina 25-40 mm. Disk florets 60+; corollas 6-7 mm, lobes yellow; anthers dark brown or black, appendages dark or yellowish. Achenes 5-7 mm, glabrous or apically hairy; pappus of 2 aristate scales 1.9-3 mm plus 0-1 deltate scales 0.5-0.8 mm. Fl. Aug-Sep. 2n = 102.
Roadsides, fields, wastelands. Widely cultivated and sometimes naturalized in China [native to North America; widely cultivated in temperate areas].
Helianthus tuberosus is a vegetable crop and widely naturalized.