Helianthus tuberosus
Helianthus longifolius
girasole, hélianthe scrofuleux, Jerusalem artichoke, Jerusalem sunflower, rough sunflower, topinambour, tuberous sunflower
longleaf sunflower, smooth sunflower
erect, scabro-hispid to hirsute (sometimes glaucous).
(green or purplish) erect, glabrous.
mostly cauline; opposite or alternate proximally, usually alternate distally;
petioles 2–8 cm (often ± winged);
blades (3-nerved from near bases) lanceolate to ovate, 10–23 × 7–15 cm, bases broadly to narrowly cuneate, margins entire or serrate (flat), abaxial faces puberulent or hirsutulous to tomentulose and gland-dotted (abaxial) or ± scabrous (adaxial).
mostly basal; opposite;
petioles 0–1 cm;
blades linear to narrowly obovate, 13–30 × 0.7–2 cm, bases cuneate, margins entire or obscurely serrate, faces glabrous, not gland-dotted (cauline smaller).
1–15 cm.
4–11 cm.
hemispheric, (10–25 ×) 8–12 mm.
hemispheric, 8–12 mm diam.
10–20;
laminae 25–40 mm.
8–13;
laminae 10–19 mm (abaxial faces not gland-dotted).
60+;
corollas 6–7 mm, lobes yellow;
anthers dark brown or black, appendages dark or yellowish.
35+;
corollas 4.2–5.5 mm, lobes yellow;
anthers dark, appendages dark.
(often dark green, drying nearly black) 22–35 (bases appressed, apices ± spreading, sometimes reflexed in fruit), lanceolate, 8.5–15 × 2–4 mm (subequal), (margins ciliate) apices acuminate, abaxial faces hispidulous or puberulent, gland-dotted.
18–23, linear-linear, 5–11 × 1–2.5 mm, (margins ciliolate) apices ± attenuate, abaxial faces glabrate or glabrous.
3–15.
3–12.
5–7 mm, glabrous or distally hairy;
pappi of 2 aristate scales 1.9–3 mm plus 0–1 deltate scales 0.5–0.8 mm.
2–3 mm, glabrate;
pappi of 2 aristate scales 1.4–2.5 mm.
8–9 mm, 3-toothed (apices hairy).
6–8 mm, weakly 3-toothed (apices hairy).
= 102.
= 34.
Helianthus tuberosus
Helianthus longifolius
Helianthus tuberosus is variable, probably in part stemming from hybridization with other polyploids, including H. pauciflorus, H. resinosus, and H. strumosus. Helianthus tuberosus is so widely spread as a weedy species that its original distribution is difficult to discern. It has been used as a food plant for its tubers by native Americans (although not necessarily domesticated or even cultivated); it has been developed as a crop primarily in Europe, where it has become widely naturalized. The common name Jerusalem artichoke is a misnomer, as explained by C. B. Heiser (1976).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Helianthus longifolius is locally escaped from a planting in one county in North Carolina. It is locally abundant where it occurs. It is not similar to or closely related to any other species; natural hybrids of H. longifolius with H. atrorubens and H. occidentalis are known.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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