Tropaeolum tuberosum

The Tuberous Nasturtium or Tropaeolum tuberosum is a climbing plant that is as beautiful in the garden as it is appreciated in cooking. This fully edible botanical species is still one of the main food resources for Andean populations today, who cultivate it on the high plateaus of Peru and Bolivia. Like a Dahlia or a Jerusalem artichoke, it produces fleshy roots underground during the entire growing season, with a fine, aromatic, and spicy flavour. Its flowering, in late summer, takes the form of orange trumpets, adorning long leafy stems that can reach a length of 2.5 meters (8 feet). Discover or rediscover this charming ancient vegetable!

Tropaeolum tuberosum, like all nasturtiums, belongs to the family Tropaeolaceae. This vigorous plant, perennial by its tuber, is native to the Andes, where it can grow at high altitudes, in sometimes poor soils, among weeds. Like the potato, it offers excellent yields: a single tuber can produce up to 700 grams of tubers arranged in a string during one growing season. These fleshy roots, shaped like elongated pears, measuring 5 to 15 cm (2 to 6in) in length, pearly and light yellow in colour, streaked with purple, produce woody climbing stems that can reach up to 2.5 metres (8 feet) under favourable conditions. They are adorned with typical nasturtium foliage: borne by a central petiole, all rounded and divided into 5 rounded lobes, the leaves are grey-green, with fine lighter veins. The flowering is late; it only begins at the end of August. The flowers, tubular in shape, surrounded by a red calyx with a spur, open into yellow-orange corollas with a brown throat. They hang from long peduncles in the axils of the leaves, along the stems.

In this nasturtium, everything is edible: its young leaves and flowers can be consumed raw in salads (or cooked as a green vegetable for the leaves). The tubers, when raw, have a pungent flavour that pairs well with other raw vegetables (cabbage, beetroot, celery, cucumbers), which can be accompanied by some walnut kernels and cheese cubes (feta, goat, Comté). This pungent aspect disappears when cooked, giving way to a very mild, round, aromatic flavour, which evokes violets, pepper, liquorice... These roots can be prepared like potatoes: boiled or steamed with their skin, accompanied by butter or cream, garnished or dressed with vinaigrette, or thinly sliced and sautéed in a pan, for example. In Bolivia, they are prepared as a compote and sweetened with molasses.

This tuberous nasturtium is a somewhat hardy plant, especially if the soil is damp in winter, so it should be dug up and stored at the first frosts, like a Dahlia. In the vegetable garden, space the plants about 1 metre (3 feet) apart in all directions, and provide a support for the stems to climb. In the garden, let it cover the ground if you have enough space: the result will be astonishing and charming at the same time. With its moderate growth, occupying about 2 m (7 feet) in all directions, it is perfect for dressing up a fence in a unique way. You can also cultivate it in a pot, where it will elegantly cascade with its leaves and flowers.