When around 1850 blight or mildew caused in potatoes in Ireland and Europe crop failure and famine was looked for replacements on all continents. Most tubers met not (yet) in our climate and remained small (oca (Oxalis tuberosa), mashua (Tropaeolum tuberosum), ulluco (Ullucus tuberosus)). By finding a cupper solution as a pesticide, and use of resistant potato varieties, the development of tubers of a different nature remained sidelined.
But there are to grow interesting, useful nature tubers. Usually you can cover the ground from frost e.g. with leaves, so that you can harvest until winter.

Jerusalem artichoke (Helianthus tuberosus). Fuseau and Helianthi are smooth, so almost knot -free varieties. The sweet tubers contain namely some inulin. This sugar (polysaccharide) is good for diabetics. Peel or brush the tubers, or peel them after cooking (not too long). Raw eating can. Put on peeled tubers some vinegar or lemon juice to prevent discoloring. Blanched young shoots can also be eaten. The foliage is like sunflower 1.5 to 3.5 m in height. Therefore useful as a windshield. Fine for the sheep. You can hardy tubers harvest from November. Each forgotten nodule becomes a new plant. Even the eyes of shells grow. Easy to grow, little problems, big yield.
Inulin is a polysaccharide (C6H10O5) that is created by many Asteracea as a food reserve. We find it also in dahlia (edible tubers!), artichoke, Jerusalem artichoke.

The Paleleaf woodland sunflower (Helianthus strumosus) is related to the sunflower and Jerusalem artichoke. He can be 2m high. Harvested tubers can only be kept for several days, but you can leave them frost free in the ground.

knollenThe sweet potato (ipomoea batatas) is a perennial plant of the morning glories family (Convolvulaceae) whose pink or white tubers have a white, yellow, red-brown or purple skin. As the name indicates, they can be used as a sweet potato. There are about 400 varieties worldwide. They are climbing 2 to 3 m high. The young leaves can be cooked like spinach. Tubers from the grocery store can also be used as planting material.

Crosne (or Chinese artichoke, Stachys affinis) are white shrimp- and spiral shaped nodules that are eaten brushed clean, crisp raw, or spicy stewed. You cook the tubers in about five minutes until ‘al dente’, or bake them raw for in salads. You can also preserve them in vinegar. They have a nutty potato flavor. You grow and use them as potatoes. The plant looks a bit like mint. Harvesting from November to April.

The mashua (Tropaeolum tuberosum) is a 2 -meter-high climbing plant related to the nasturtium (Tropaeolum majus). The pear -shaped, knobbly tubers are striking red, yellow and white in color and up to 10 cm tall. 20-30 tonnes per hectare can be harvested.
The mashua is cooked as a vegetable and in soup, to soften the sharp taste. You can also place the tubers in the sun for several days. The spicy leaves are used as a spice.

The tubers of yellow nutsedge (Cyperus esculentus) can be eaten raw or (like peanuts) roasted, ground into flour for dough and batter, or roasted and ground used as a cocoa or coffee substitute.
The plant looks like a large clump of grass with leaves of 30 to 40 cm. The pale brown nodules are large as hazelnut. A shrub forms masses tubers, you can replant them. Since 1984, the Netherlands have a control program against this stubborn yellow nutsedge, with a ban on infected fields. So keep a cultivation under control (in pots, there is little to no sperm formed).
In Spain they are ground sold as drink: horchata de chufa. (Cleaning, soaking, grinding or mixing with water until you have a paste, add the same amount of cane sugar and 24 hours in the refrigerator, even 2.5x add as much water and filter it. Adding some cinnamon. Possibly a mint leaf.)

The earthnut (Bunium bulbocastanum) is an in the Benelux wild growing plant from the Apiaceae family, in the meantime on the red list (endangered species).
The fleshy roots are swollen (almost spherical), black and up to 2 ½ cm thick. They can be eaten raw or cooked. The taste resembles that of roasted chestnuts. Also the seeds, and flowers can be used as a spice.

The groundnut (Apios America), is a legume and high climber with beautiful (great?) fragrant flowers. The highly nutritious tubers are like sausages serried in a rosary. In their third year they are large enough to harvest, with up to 2.5 kg yield per plant. Because of that long waiting, scale production never became anything.

Although they resemble, by their form, to beans, peanut (Arachis hypogaea) is a legume, and an underground growing groundnut. Peanuts require an average temperature of 20-30°C and a humidity of 80%. So here it is only under glass.

Yam (Dioscorea) is a tropical edible tuber. That can be round, oblong or branched and white, yellow or pink colored. The weight of a fully grown tuber can be 1 kg to over 50 kg.
The tubers are harvested ten to twelve months after planting and can be stored up to six months in temperatures up to 25°C. They can be boiled, baked or fried as potatoes.
The yam is in the tropics as a staple food as important as the potato in temperate regions.

Chinese Yam (or wild yam, Dioscorea batatas) is the only one that thrives in our region. It is a perennial. However, the plant dies off completely above ground. The root can stay in the ground in winter.

The first year the climber goes to more than one meter high, later they can make 3-6 meters long tendrils.
The small air bullets that grow on the stems around the plant, can also be used, such as fried "potatoes", but also to plant new yams: 3 years waiting for a harvest. It can more quickly by planting rhizomes. The roots are easier to harvest if you plant them in mounds (or ridges) of 30 to 40 cm.

The perennial Peruvian ground apple (apple-of-the-earth) or yacon (Smallanthus sonchifolius, also called Polymnia edulis, P. sonchifolia), originates from the Andes and is related to the sunflower and Jerusalem artichoke.
From summer 10-20 brown-red, oblong tubers (such as Dahlia) are formed underground. The yield starts with one kilo, but after several years adapting to the ground the total weight can be up to 10 kg per plant. During the growth you can propagate the plant quickly by cuttings.
Harvest after the first frost. The plant is not hardy. The smaller reddish nodules can hoard frost free to plant next year. The larger taste fresh-sweet and very juicy and are used in fruit salads and hot dishes, in stir-frying and deep-frying.

Flowering and seed setting often fail in our climate, but the little orange yellow sun flowers are also edible.
From the huge leaves one can make a special and sweet tea.
Of the tubers is also made a sweet syrup. Which includes among others inulin, a sugar that is not digested by the body and therefore  also is suitable for people with diabetes.