Tropaeolum /trəˈpiːələm, troʊ-/,[2][3] commonly known as nasturtium (/nəˈstɜːrʃəm, næ-/;[4][5][6] literally "nose-twister" or "nose-tweaker"), is a genus of roughly 80 species of annual and perennial herbaceous flowering plants.

The genus Tropaeolum, native to South and Central America, includes several very popular garden plants, the most common being T. majus, T. peregrinum and T. speciosum.

One of the hardiest species is T. polyphyllum from Chile, the perennial roots of which can survive the winter underground at elevations of 3,300 metres (11,000 ft).

Plants in this genus have showy, often intensely bright flowers and rounded, peltate (shield-shaped) leaves with the petiole in the centre.

The flowers are bisexual and zygomorphic, with five petals, a superior three-carpelled ovary, and a funnel-shaped nectar spur at the back, formed by modification of one of the five sepals.

[10] Tropaeolum majus was named by the Swedish botanist Carl Linnaeus, who chose the genus name because the plant reminded him of an ancient custom: After victory in battle, the Romans erected a trophy pole (or tropaeum, from the Greek tropaion, source of English "trophy") on which the vanquished foe's armour and weapons were hung.

In his herbal, John Gerard compared the flowers of the "Indian Cress" to those of the forking larkspur (Consolida regalis) of the buttercup family.

[11] He wrote: "Unto the backe part (of the flower) doth hange a taile or spurre, such as hath the Larkes heele, called in Latine Consolida regalis.

[15] The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit: The blue nasturtium (Tropaeolum azureum) is a tender species from Chile which has violet-blue flowers with white eyes that can be as much as 4 cm (1+1⁄2 in) across.

[19] The Canary creeper (Tropaeolum peregrinum) is a trailing and climbing half-hardy annual species with wiry stalks and palmately lobed leaves.

[11] It is a very hardy species; the tubers can grow at depths of 60 cm (24 in) enabling the plant to survive at altitudes of as much as 3,300 metres (10,000 ft) in the Andes.

It sends up shoots that thread their way through hedges and shrubs and, when they emerge into the light, bear brilliant red flowers among small, five or six-lobed leaves.

[21] Three-coloured Indian cress (Tropaeolum tricolor) is another tuberous, climbing species grown for its attractive red, purple and yellow tubular flowers.

The flower has most often been consumed, making for an especially ornamental salad ingredient; it has a slightly peppery taste reminiscent of watercress and is also used in stir fry.

The unripe seed pods can be harvested and dropped into spiced vinegar to produce a condiment and garnish, sometimes used in place of capers.

[29] In Germany, licensed physicians can prescribe the herbal antibiotic Angocin Anti-Infekt N, made from only nasturtium and horseradish root.