This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This well-known plant, although a perennial in its native home, Peru, is generally treated as an annual in cultivation. As a decorative flower-garden plant it is referred to in Vol, II, p. 73, and that is the chief role it and its varieties and hybrids play in British gardens. It practically has no other commercial value. The leaves, young shoots, and flowers are sometimes eaten as salad, or between thin slices of bread and butter. They possess a "cressy" flavour, although the plants really belong to the Geranium family.
The tubers of T. tuberosum are a favourite dish in South America, where they are first boiled and afterwards frozen before being eaten.
They are yellowish mottled with crimson, but are more valuable as flowering plants in Britain than as herbs or salads. (See Vol. II, p. 111).