Tropæ'olm, a genus of plants variously included by different botanists in the natural orders Tropeolaceæ and Geraniaceæ. It is numerous in species, all of which are natives of South America. They are annual or perennial herbs of trailing or climbing habit, having simple peltate leaves which are often peltately divided into several leaflets. The genus comprises the Great Indian Cress or Nasturtium (q.v.), T. majus, and the Small Indian Cress (T. minus), which are familiar in nearly every garden, along with the Canary-bird Flower or Canary Creeper (T. peregrinum), and many brilliant perennial species not so generally cultivated in Britain.
The best known of the perennials is the Flame-flowered Nasturtium (T. speciosum), which, though introduced from its native country, Chili, so recently as 1846, is now one of the most frequent and brilliant ornaments of cottage walls throughout Scotland, particularly in the highland or northern districts, and also in North Wales. It is the envy of southern tourists, who carry roots of the plant home with them in the hope of establishing it in their own gardens, but rarely succeed. It requires peculiar atmospheric conditions to induce it to grow and flower freely; moderate exposure to light, such as would be afforded by a west aspect, high atmospheric humidity and cool nights, with deep moist but well-drained soil, are essential to its healthy growth. It is easily propagated by its creeping underground rhizomes. There are several other hardy and greenhouse perennials with tuberous roots in cultivation, all of a very ornamental character. The tubers of T. tuberosum, a native of Peru, are edible.