Helianthus tuberosus (Jerusalem artichoke)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Tribe: Heliantheae
Genus: Helianthus
Species: H. tuberosus
Binomial name: Helianthus tuberosus
Synonyms: Helianthus esculentus, Helianthus serotinus, Helianthus tomentosus, Helianthus tuberosus var. subcanescens.
Common names: Jerusalem artichoke, Sunroot, Sunchoke, Earth apple, Topinambour

Helianthus tuberosus is a species of perennial sunflower with short rhizomes and well-developed tubers. It is native to eastern North America. It and its cultivars are widely cultivated as a root vegetable.

Helianthus tuberosus can be invasive and can be seen throughout North and South Islands growing wild in waste places and along roadsides and occasionally in cultivated areas. These wild plants are usually spread by the dumping of garden waste.
This herbaceous perennial plant can grow up 2.4 m tall. It dies back in winter and survives as underground rhizomes, the "artichoke".

The stems are light green to reddish brown, terete, and hairy; the stem hairs are white, widely spreading, and slightly stiff. They branch occasionally along the upper one-half of their length.

The rough, sandpapery, ovate, opposite or alternate leaves occur along lower to middle stems of this plant, while alternate leaves occur along the upper stems. There is some variation across populations to what extent the leaves are opposite or alternate. The leaf blades can be up to 25 cm long and up to 10 cm across, although they are usually closer to one-third or one-half of this size. The leaf blades are lanceolate to ovate in shape and nearly entire (toothless) to serrate-dentate along their margins. The bases of leaf blades are wedge-shaped to rounded, while their tips are acute. The upper blade surface is medium green and nearly glabrous to minutely stiff-hairy, while the lower blade surface is pale-medium green and minutely stiff-hairy to short-pubescent. The hairiness of the leaf blades varies to some extent across different populations of plants. The petioles of the leaves are up to 6 cm long, becoming increasingly winged toward their blades; they are light green and minutely stiff-hairy to pubescent. The petioles become progressively shorter as they ascend along the stems.
The upper stems terminate in one or more flower heads on peduncles up to 20 cm long. The flowerheads are 7.6-10 cm across and have 10–15 bright yellow rays. In New Zealand, they appear during April.
The plant can reproduce by seed but also by resprouting from tubers and fragments left in the ground.

The tubers are edible and are produced just below the ground on thin white rhizomes. They are segmented and knobbly, 2.5-10 cm long, and have crisp, white flesh. They can be eaten raw and they are usually cooked like potatoes.