Tropaeolum majus

The Latin specific epithet majus means “larger”.[4]

It is a fast-growing plant, with trailing stems growing to 3–6 ft (0.91–1.83 m). The leaves are large, nearly circular, 3 to 15 centimetres (1.2 to 5.9 in) in diameter, green to glaucous green above, paler below; they are peltate, with the 5–30 cm long petiole near the middle of the leaf, with several veins radiating to the smoothly rounded or slightly lobed margin. The flowers are 2.5–6 cm diameter, with five petals, eight stamens, and a 2.5–3 cm long nectar spur at the rear; they vary from yellow to orange to red, frilled and often darker at the base of the petals. The fruit is 2 cm broad, three-segmented, each segment with a single large seed 1–1.5 cm long.[5][6]

The garden nasturtium is used as a food plant by the larvae of some Lepidoptera species including the dot moth[9] and the garden carpet moth.[10] A common pest found on nasturtiums is the caterpillar of the large white or cabbage white butterfly.[11]

The species has become naturalized in parts of the United States (California, New York, Pennsylvania, New Hampshire, Massachusetts, Connecticut and Virginia),[12][13] as well as parts of Europe, such as Gibraltar,[14] and Asia, Africa and Australia.[12] It is also listed as invasive in Hawaii and Lord Howe Island, Australia.[6]

Roses and Nasturtiums in a Vase by Henri Fantin-Latour

Tropaeolum majus cultivars are widely grown as easy annual plants, for poor, damp soil in full sun. The large seeds are easy to handle individually. As they do not tolerate heavy frost they are best sown under glass in heat, and planted out after all danger of frost has passed. Alternatively, as they are fast-growing, they may be sown in situ in May or June. Many flower colours are available, in the warm spectrum from cream through yellow, orange, red and maroon. Some have highly decorative marbling on the leaves. The groups Whirlybird Series[15] and Alaska Series[16] have gained the Royal Horticultural Society’s Award of Garden Merit.[17]

Culinary

Salad with flowers and leaves

All of the above-ground parts of the plants are edible.[18] 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 flowers contain about 130 mg vitamin C per 100 grams (3.5 oz),[19] about the same amount as is contained in parsley.[20] Moreover, they contain up to 45 mg of lutein per 100 gr,[21] which is the highest amount found in any edible plant. The unripe seed pods can be harvested and dropped into spiced vinegar to produce a condiment and garnish, sometimes used in place of capers.[22]

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  Botanical scan
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  Some color varieties
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  Flowering yellow and red
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  Flower showing nectar spur
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  Underside of leaf showing petiole attachment
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  Flower cut through to show structure
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  Immature fruit
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  Lobed leaf morphology