Nasturtium

When I lived in London, nasturtium grew wild in my garden but it was ages before I realised I could eat it.

Nasturtium plants	Nasturtium flowers and leaves	Unripe nasturtium fruits

Species:	Tropaeolum majus.
Origin:	South America.
Source:	Nasturtium originates from Peru and was introduced to Europe by the Spanish conquistadors. It is a common ornamental plant less frequently used for cooking than other cresses.
Used Part:	Fresh leaves. Unripe nasturtium fruits can be pickled and used as a substitute for capers.
Family:	Tropaeolaceae (nasturtium family). Confusingly, the plant is regarded as a cress, whereas both garden cress and water cress belong to the different family brassicaceae (cabbage) and water cress is botanically named nasturtium officinale.
Effect:	Nasturtium and its relatives display a spicy aroma and a refreshing, peppery-pungent taste lasting only a few seconds. The aroma components are volatile and susceptible to both heat and moisture, so nasturtium and other cresses are always used fresh and should not be boiled, baked or otherwise heated.
Etymology:	The genus name tropaeolum is the Latin diminutive of tropaeum "trophy" from Greek tropaion "turning" or "retreat" (cf. Greek trepein "to turn"). Species name majus is Latin for "greater". The combined name refers to the growing habits of the plant, which is able to conquer any open space by twisting and turning its shoots to fill gaps and to seek the sun.
	The name nasturtium (used by the Romans for several cress-like plants and especially garden cress) probably derives from nasi-tortium "nose pain" from nasus "nose" and the verb torquere "torment" and refers to the sharp, pungent aroma. The term "nasturtium" has become the botanical genus name for water cress and in English it is commonly used for the water cress plant of new-world origin that was unknown to the Romans.
	In many languages, nasturtium bears names that relate to its origin from Latin America, e.g. French cresson d'Inde or Swedish Indiankrasse "native American cress". Other names include references to "Latin" in reference to its import by members of Catholic orders, e.g. Turkish lâtin çiçeği, Bulgarian latinka and Kurdish ladan. The German kapuzinerkresse, French capucine, Dutch capucienerkers, Italian cappuccina, Arabic nabat al-kabbusin and Russian kaputsin-kress also refer to introduction by Catholic monks and the similar shapes of nasturtium flowers and the cowl of Capuchin monks.
	Confusingly, nasturtium is the botanical name of water cress and not of the plant whose common name is "nasturtium", especially as the isothiocyanate principle of water cress, wasabi, rocket and mustard, gluconasturtin, does not occur in nasturtium.
Uses:	Nasturtium and other cresses are considered interchangeable in the kitchen and are popular in Europe and North America where they are used for spreads (especially those based on cottage cheese) and salads. In Europe, cress leaves are not commonly combined with other fresh herbs but they are compatible with the fines herbes of French cuisine and may be used together with each of them. Leaves or flowers of nasturtium are commonly used to flavour herbal vinegar and cress is also very good for herb sauces.
	The disadvantage of nasturtium as with other cresses is that the leaves cannot be dried and thus are rarely traded. Nasturtium is an annual that grows quickly and easily in the garden with minimal effort. Its orange and yellow flowers are very decorative and have additional use as the buds and unripe fruits can be pickled and serve as a good substitute for capers.