32.
Helianthus tuberosus
Linnaeus, Sp. Pl. 2: 905. 1753.
Jerusalem artichoke , topinambour
Helianthus tomentosus
Michaux;
H. tuberosus
var.
subcanescens
A. Gray
Perennials
, 50—200+ cm (rhizomatous, producing tubers late in growing season).
Stems
erect, scabro-hispid to hirsute (sometimes glaucous).
Leaves
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).
Heads
3—15.
Peduncles
1—15 cm.
Involucres
hemispheric, (10—25 ×) 8—12 mm.
Phyllaries
(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.
Paleae
8—9 mm, 3-toothed (apices hairy).
Ray florets
10—20; laminae 25—40 mm.
Disc florets
60+; corollas 6—7 mm, lobes yellow; anthers dark brown or black, appendages dark or yellowish.
Cypselae
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
n
= 102.
Flowering late summer—fall. Roadsides, fields, waste areas; 0—1000(—1500) m; Man., N.B., N.S., Ont., P.E.I., Que., Sask.; Ala., Ark., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; cultivated and adventive in Europe.
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).
