Helianthus tuberosus
Helianthus glaucophyllus
girasole, hélianthe scrofuleux, Jerusalem artichoke, Jerusalem sunflower, rough sunflower, topinambour, tuberous sunflower
giant sunflower, hélianthe géant, tall sunflower, whiteleaf 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).
mostly cauline; opposite (proximal) or alternate;
petioles 1–3 cm;
blades (light to dark green, abaxially whitish, 3-nerved), lanceolate to lance-ovate, 9–18 × 2.5–7 cm, bases abruptly narrowed, margins serrate, faces glabrous (abaxial) or sparsely scabrous (adaxial), not gland-dotted (abaxial glaucous).
1–15 cm.
0.5–8 cm.
hemispheric, (10–25 ×) 8–12 mm.
hemispheric, 8–9 mm diam.
10–20;
laminae 25–40 mm.
5–8;
laminae 12–14 mm (abaxial faces not gland-dotted).
60+;
corollas 6–7 mm, lobes yellow;
anthers dark brown or black, appendages dark or yellowish.
20–35;
corollas 5–6 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.
12–15, lanceolate to ovate, 8–9 × 1.8–3 mm, (margins ciliate) apices acuminate.
3–15.
3–15+.
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.
3.5–3.8 mm, glabrous;
pappi of 2 aristate scales 3.2–3.5 mm.
8–9 mm, 3-toothed (apices hairy).
6.2–7.5 mm, 3-toothed (apices hairy).
= 102.
= 34.
Helianthus tuberosus
Helianthus glaucophyllus
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 glaucophyllus is found in the southern Blue Ridge Province. It is distinguished from H. microcephalus, with which it shares relatively small heads, by glabrous or sparsely scabrous, glaucous leaves. Its closest relative may be H. decapetalus, which has larger heads and, usually, longer phyllaries.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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