Jerusalem artichoke

Helianthus tuberosus is a herbaceous perennial plant growing to 1.5–3 m (4 ft 11 in – 9 ft 10 in) tall with opposite leaves on the lower part of the stem but alternate towards the top.[6] The leaves have a rough, hairy texture. Larger leaves on the lower stem are broad ovoid-acute and can be up to 30 cm (12 in) long. Leaves higher on the stem are smaller and narrower.[7]

The flowers are yellow and produced in capitate flowerheads, which are 5–10 cm (2–4 in) in diameter, with 10–20 ray florets and 60 or more small disc florets. The flowers are briefly fragrant, giving off a light, vanilla-chocolate perfume.[7]

The tubers are often elongated and uneven, typically 7.5–10 cm (3–3+7⁄8 in) long and 3–5 cm (1–2 in) thick, and vaguely resembling a ginger root in appearance, with a crisp and crunchy texture when raw. They vary in color from pale brown to white, red, or purple.[5][8]

The tubers can be eaten raw, cooked, or pickled.[9]

Before the arrival of Europeans, indigenous peoples cultivated H. tuberosus as a food source. The tubers persist for years after being planted, so that the species expanded its range from central North America to the eastern and western regions. Early European colonists learned of this, and sent tubers back to Europe, where it became a popular crop and naturalized there. It later gradually fell into obscurity in North America, but attempts to market it commercially have been successful in the late 1900s and early 2000s.[7][10]

The tuber contains about 2% protein, no oil, and little starch. It is rich in the carbohydrate inulin (8 to 13%[11]), which is a polymer of the monosaccharide fructose. Tubers stored for any length of time convert their inulin into its component fructose. Jerusalem artichokes have an underlying sweet taste because of the fructose, which is about one and a half times as sweet as sucrose.[10]

Wasps feeding on the stems of Jerusalem artichokes

It has also been reported as a folk remedy for diabetes:[10] since inulin is not assimilated in the intestine, it doesn't cause a glycemic spike as potatoes would. Temperature variances have been shown to affect the amount of inulin the Jerusalem artichoke can produce. It makes less inulin in a colder region than when it is in a warmer region.[12]

Jerusalem artichoke flowers

Despite one of its names, the Jerusalem artichoke has no relationship to Jerusalem, and it is not a type of artichoke,[13][14] though the two are distantly related as members of the daisy family. Italian settlers in the United States called the plant girasole, the Italian word for sunflower, because of its familial relationship to the garden sunflower (both plants are members of the genus Helianthus). Over time, the name girasole (pronounced closer to [dʒiraˈsuːlə] in southern Italian dialects) was corrupted to Jerusalem.[15][16][17] An alternative explanation for the name is that the Puritans, when they came to the New World, named the plant with regard to the "New Jerusalem" they believed they were creating in the wilderness.[10] Also, various other names have been applied to the plant, such as the French or Canada potato, topinambour, and lambchoke. Sunchoke, a name by which it is still known today, was invented in the 1960s by Frieda Caplan, a produce wholesaler who was trying to revive the plant's appeal.[10]

The artichoke part of the Jerusalem artichoke's name comes from the taste of its edible tuber. Samuel de Champlain, the French explorer, sent the first samples of the plant to France, noting its taste was similar to that of an artichoke.[18][19]

The name topinambur, in one account, dates from 1615, when a member of the Brazilian coastal tribe called the Tupinambá visited the Vatican at the same time that a sample of the tuber from Canada was on display there, presented as a critical food source that helped French Canadian settlers survive the winter. The New World connection resulted in the name topinambur being applied to the tuber, the word now used in French, German, Italian, Polish, Romanian, Russian, and Spanish.[20][21]

Jerusalem Artichoke Flowers, Claude Monet, 1880, National Gallery of Art, Washington D.C.

Jerusalem artichokes were first cultivated by the Indigenous peoples of the Americas—this extensive cultivation obscures the exact native range of the species.[4] The French explorer Samuel de Champlain discovered that the native people of Nauset Harbor in Massachusetts had cultivated roots that tasted like artichoke. The following year, Champlain returned to the same area to discover that the roots had a flavor similar to chard[22] and was responsible for bringing the plant back to France. Some time later, Petrus Hondius, a Dutch botanist, planted a shriveled Jerusalem artichoke tuber in his garden at Terneuzen and was surprised to see the plant proliferate.[22] Jerusalem artichokes are so well-suited for the European climate and soil that the plant multiplies quickly. By the mid-1600s, the Jerusalem artichoke had become a very common vegetable for human consumption in Europe and the Americas, and was also used for livestock feed in Europe and colonial America.[10] The French in particular were especially fond of the vegetable, which reached its peak popularity at the turn of the 19th century.[10] The Jerusalem artichoke was titled 'best soup vegetable' in the 2002 Nice Festival for the Heritage of the French Cuisine.

The French explorer and Acadia's first historian, Marc Lescarbot, described Jerusalem artichokes as being "as big as turnips or truffles", suitable for eating and taste "like chards, but more pleasant". In 1629, English herbalist and botanist, John Parkinson, wrote that the widely grown Jerusalem artichoke had become very common and cheap in London, so much so "that even the most vulgar begin to despise them". In contrast, when Jerusalem artichokes first arrived in England, the tubers were "dainties for the Queen".[22]

Lewis and Clark ate the tubers, prepared by an indigenous woman, in modern-day North Dakota.[23]

They have also been called the "Canadian truffle".[24]

Young plants in a garden

Jerusalem artichoke tubers

Unlike most tubers, but in common with many other members of the Asteraceae (including the artichoke), the Jerusalem artichoke tubers store their carbohydrate as inulin (not to be confused with insulin) rather than as starch. So, Jerusalem artichoke tubers are an important source of inulin used as a dietary fiber in food manufacturing.[25]

Crop yields are high, typically 16–20 tonnes per hectare (7–9 short ton/acre) for tubers, and 18–28 tonnes per hectare (8–12 short ton/acre) green weight for foliage. Tubers remaining in the ground lie dormant over winter and can handle temperatures as low as −30 °C (−22 °F).[26] Jerusalem artichoke also has potential for production of ethanol fuel, using inulin-adapted strains of yeast for fermentation.[5]

The tubers are used for cooking and baking in the same ways as potatoes,[27] but unlike the potato they can also be eaten raw.[26] They have a similar consistency, and in their raw form have a similar texture, but a sweeter, nuttier flavor. When raw and sliced thinly, they are fit for a salad. Their inulin form of carbohydrates give the tubers a tendency to become soft and mushy if boiled, but they retain their texture better when steamed. The inulin cannot be broken down by the human digestive system[28] but it is metabolized by bacteria in the colon. This can cause flatulence and, in some cases, gastric pain. John Gerard's Herbal, printed in 1621, quotes the English botanist John Goodyer on Jerusalem artichokes:[29]

which way soever they be dressed and eaten, they stir and cause a filthy loathsome stinking wind within the body, thereby causing the belly to be pained and tormented, and are a meat more fit for swine than men.

Jerusalem artichokes have 650 mg potassium per 1 cup (150 g) serving. They are also high in iron, and contain 10–12% of the USRDA of fiber, niacin, thiamine, phosphorus, and copper.[30]

Jerusalem artichokes can be used as animal feed, but they must be washed before being fed to most animals. Pigs can forage, however, and safely eat them directly from the ground. The stalks and leaves can be harvested and used for silage, though cutting the tops greatly reduces the harvest of the roots.

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• Helianthus tuberosus – Plants for a Future database
• Jerusalem artichoke – Ohio Perennial & Biennial Weed Guide
• NutritionData, Complete nutritional info.
• Purdue University Alternative Field Crops Manual: Jerusalem Artichoke