Helianthus tuberosus
Helianthus porteri
girasole, Jerusalem artichoke, Jerusalem sunflower, topinambour, tuberous sunflower
confederate daisy, Porter's sunflower
erect, scabro-hispid to hirsute (sometimes glaucous).
erect, usually sparsely strigose, sometimes hispid as well.
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 0–0.2 cm;
blades (± 3-nerved distal to bases) narrowly lanceolate to linear, 5–11.5 × 0.15–1 cm, bases cuneate, margins entire (often ± ciliate proximally), faces sparsely strigose or scabrous to glabrate, sparsely gland-dotted.
1–15 cm.
1–10 cm.
hemispheric, (10–25 ×) 8–12 mm.
hemispheric, 5–6 mm diam.
10–20;
laminae 25–40 mm.
7–8;
laminae (10–)15–20 mm.
60+;
corollas 6–7 mm, lobes yellow;
anthers dark brown or black, appendages dark or yellowish.
30+;
corollas 2.8–3.5 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.
11–17, linear, 5.5–8 × 0.8–1.3 mm (margins sparsely hispido-ciliate, hairs 0.5–1.2 mm), apices acute to acuminate, abaxial faces glabrate, not gland-dotted.
3–15.
usually 5+.
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.
2.2–2.3 mm, sparsely puberulent (bases and apices);
pappi 0.
8–9 mm, 3-toothed (apices hairy).
(ovate) 3.5–4.6 mm, entire (1-toothed).
= 102.
= 34.
Helianthus tuberosus
Helianthus porteri
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 porteri was established at Rocky Face Mountain, North Carolina, following its introduction as part of an ecologic experiment. Where it occurs, H. porteri produces conspicuous massed floral displays when in bloom. It is remarkably similar morphologically in its reduced habit, epappose cypselae, conic receptacles, and unlobed, mucronate pales to Heliomeris (Viguiera sect. Heliomeris), and it is treated under Viguiera in most southeastern United States treatments; its style appendages and chromosome number agree with molecular phylogenetic data in placing it within Helianthus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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