Helianthus tuberosus
Helianthus verticillatus
girasole, Jerusalem artichoke, Jerusalem sunflower, topinambour, tuberous sunflower
whorled sunflower
erect, scabro-hispid to hirsute (sometimes glaucous).
erect, glabrous (glaucous).
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).
cauline; usually whorled (3s–6s), sometimes opposite;
sessile or subsessile, petioles 0–1 cm;
blades linear to lanceolate, 7.5–18.5 × 0.7–3 cm, bases cuneate, margins serrulate or entire (flat), faces puberulent (abaxial) or hispid-strumose (adaxial), gland-dotted.
1–15 cm.
1–10 cm.
hemispheric, (10–25 ×) 8–12 mm.
broadly campanulate, 15–20 mm diam.
10–20;
laminae 25–40 mm.
10–19;
laminae 20–26 mm.
60+;
corollas 6–7 mm, lobes yellow;
anthers dark brown or black, appendages dark or yellowish.
150+;
corollas 5–7 mm, lobes yellow;
anthers dark, appendages yellow.
(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.
45–55, lance-linear, 12–18 × 2–2.5 mm, (margins ciliate) apices long-attenuate, abaxial faces glabrate to sparsely puberulent, gland-dotted.
3–15.
(1–)3–7+.
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.
4–5 mm, glabrous;
pappi of 2 aristate scales 2.2–2.5 mm.
8–9 mm, 3-toothed (apices hairy).
5–8 mm, entire or 3-toothed (apices ciliate).
= 102.
= 34.
Helianthus tuberosus
Helianthus verticillatus
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.)
Of conservation concern.
Helianthus verticillatus is relatively uncommon and was recently rediscovered in scattered locations; it is a candidate for federal listing as an endangered species. It has been suggested to be a hybrid of H. angustifolius and H. eggertii or H. grosseserratus; no supporting evidence has been found to corroborate that suggestion.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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