| Tropaeolum | |
|---|---|
 | |
| Tropaeolum majus | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Brassicales |
| Family: | Tropaeolaceae Juss. exDC. |
| Genus: | Tropaeolum L. |
| Type species | |
| Tropaeolum majus L.[1] | |
| Species | |
About 80 species, see text. | |
| Synonyms | |
| |
Tropaeolum/trəˈpiːələm,troʊ-/,[2][3] commonly known asnasturtium (/nəˈstɜːrʃəm,næ-/;[4][5][6] literally "nose-twister" or "nose-tweaker"), is a genus of roughly 80 species ofannual andperennial herbaceousflowering plants. It wasnamed byCarl Linnaeus in his bookSpecies Plantarum and is the only genus in thefamilyTropaeolaceae. The nasturtiums received their common name because they produce an oil similar to that ofwatercress (Nasturtium officinale).
The genusTropaeolum,native to South and Central America, includes several very popular garden plants, the most common beingT. majus,T. peregrinum andT. speciosum. One of thehardiest species isT. polyphyllum fromChile, 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 thepetiole in the centre. The flowers are bisexual andzygomorphic, with five petals, asuperior three-carpelled ovary, and a funnel-shaped nectar spur at the back, formed by modification of one of the five sepals.[7]
Tropaeolum is a genus ofdicotyledonous annual or perennial plants, often with somewhat succulent stems and sometimes tuberous roots. The alternate leaves are hairless,peltate, and entirely or palmately lobed. The petioles or leaf stalks are long and, in many species, can twine around other stems to provide support. The flowers are bisexual and showy, set singly on long stalks in the axils of the leaves. They have fivesepals, the uppermost of which is elongated into a nectar spur. The fivepetals are clawed, with the lower three unlike the upper two. The eightstamens are in two whorls of unequal length, and the superior ovary has three segments and threestigmas on a singlestyle. The fruit is naked and nut-like, with three single seed segments.[8][9]
.jpg)
Tropaeolum wasnamed byCarl Linnaeus in his bookSpecies Plantarum.[10] He chose the genus name becauseT. majus reminded him of an ancient custom: After victory in battle, the Romans erected a trophy pole (ortropaeum, from the Greektropaion, source of English "trophy") on which the vanquished foe's armour and weapons were hung. The plant's round leaves reminded Linnaeus of shields and its flowers of blood-stained helmets.[11]
Tropaeolum was previously placed in thefamilyTropaeolaceae along with two other genera,MagallanaCav. andTrophaeastrum. Themonotypic genusMagallana was characterised by having winged fruit, and the two species ofTrophaeastrum lacked spurs. The genusTropaeolum was diagnosed only by the absence of the characteristics of the other two genera. A molecular study undertaken in 2000 foundTropaeolum to beparaphyletic when the other two genera are segregated, soMagallana andTrophaeastrum were reduced to synonyms ofTropaeolum. Tropaeolaceae was thus rendered monogeneric, a family of only one genus.[12]
The nasturtiums received their common name because they produce an oil similar to that ofwatercress (Nasturtium officinale).
"The Plant List", a collaboration between theMissouri Botanical Garden and theRoyal Botanic Gardens, Kew, includes the following accepted names ofTropaeolum species names. Some that are under review are here marked "U".[13]
.jpg)
The most common flower in cultivation is ahybrid ofT. majus,T. minus, andT. peltophorum. It is commonly known as the nasturtium (and occasionally anglicized as nasturtian). It is mostly grown from seed as a half-hardy annual, and both single and double varieties are available. It comes in various forms and colours, including cream, yellow, orange and red, solid in colour or striped and often with a dark blotch at the base of the petals. It is vigorous and easily grown and does well in sun. It thrives in poor soil and dry conditions, whereas rich soil produces much leafy growth and few flowers. Some varieties adopt a bush form while others scramble over and through other plants and are useful for planting in awkward spots or for covering fences andtrellises.[14]
The followingcultivars have gained theRoyal Horticultural Society'sAward of Garden Merit:
Theblue 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.[18]
Tropaeolum brachyceras has 2.5 cm (1 in) yellow flowers with purplish markings on wiry, climbing stems. It is a half-hardy perennial from Chile and may remaindormant for several years before being sparked into growth by some unknown trigger factor.[18]
Tropaeolum hookerianum is a tuberous-rooted species from Chile. There are two subspecies,T. h. austropurpureum which has violet-purple flowers andT. h. pilosum with yellow flowers.[18]
TheCanary creeper (Tropaeolum peregrinum) is a trailing and climbing half-hardy annual species with wiry stalks and palmately lobed leaves. The pale yellow, fringed flowers are borne on long stalks. It originated fromPeru but may first have been cultivated in theCanary Islands before being introduced into Western Europe.[11]
Wreath nasturtium (Tropaeolum polyphyllum) is a prostrate plant originating from Argentina and Chile. It has silvery, deeply lobed leaves and a profusion of small, bright yellow flowers on long trailing stalks. After flowering, the plant dies back. It is a perennial with undergroundrhizomes which send up new shoots at intervals. It will survive for several years in a suitable sunny location with well-drained soil.[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.[19]
Theflame flower (Tropaeolum speciosum) is well adapted to cool, moist climates and famously does well in Scotland. 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. It is difficult to establish but is an attractive garden plant when it thrives.[11] This plant has gained the Royal Horticultural Society's Award of Garden Merit.[20]
Three-coloured Indian cress (Tropaeolum tricolor) is another tuberous, climbing species grown for its attractive red, purple and yellow tubular flowers. It comes from Chile andBolivia and is a reliable winter-growing species.[18]
Mashua (Tropaeolum tuberosum) is a perennial climbing plant from theAndes grown for its tuberous roots. It has been cultivated since ancient times, and depictions of it are found at archaeological sites pre-dating theIncas. It has leaves with five to seven lobes and small, long-spurred, red and yellow flowers. The tubers have an unpleasant smell when raw, which disappears on cooking. It is frost-hardy and produces crops of 30 tonnes per hectare at an elevation of 3,000 metres (9,800 ft) above sea level.[21] The cultivarT. tuberosum lineamaculatum 'Ken Aslet' has gained the Royal Horticultural Society's Award of Garden Merit.[22]
Species originating from the coastal areas and lower foothills make most of their growth in winter, whereas the true alpine species are summer growers. TuberousTropaeolum species are well known for occasionally remainingdormant for one or more years. The species with underground rhizomes and tubers can be propagated from these, while other species are best raised from seed. Many growers favour fresh seed, but dried seed is also often successful. Seed from the winter growing species should be sown in the autumn, while the summer growing species are best sown in the spring in well-drained compost and covered with1 to 2 cm (1⁄2 to3⁄4 in) of grit or sand. The containers should be kept at below 4 °C (39 °F) until the seedlings appear in about a month, as too high a temperature inhibitsgermination.[23]
All parts ofT. majus are edible. The flower has most often been consumed, making for an especially ornamental salad ingredient; it has a slightly peppery taste reminiscent ofwatercress and is also used instir fry. The flowers contain about 130 mgvitamin C per100 grams (3+1⁄2 oz),[24] about the same amount as is contained inparsley.[25] Moreover, they contain up to 45 mg oflutein per 100 g,[26] which is the highest amount found in any edible plant. The unripe seed pods can be harvested and dropped into seasoned vinegar to produce a condiment and garnish, sometimes used in place ofcapers.[27]
Mashua (T. tuberosum) produces an edible undergroundtuber that is a major food source in parts of theAndes.
T. majus has been used in herbal medicine for respiratory andurinary tract infections.[28]
In Germany, licensed physicians can prescribe the herbal antibiotic Angocin Anti-Infekt N, made from only nasturtium andhorseradish root.[29]
Nasturtiums are used ascompanion plants forbiological pest control, repelling some pests, acting as atrap crop for others and attracting predatory insects.[30][31] While companion planting is a widespread notion and often adopted by home gardeners, there is little but anecdotal evidence to support these claims.[32]
Tropaeolum was introduced into Spain by the Spanish botanistNicolás Monardes, who described it in hisHistoria medicinal de las cosas que se traen de nuestras Indias Occidentales of 1569, translated into English asIoyfull newes out of the newe founde worlde byJohn Frampton.[33] The English herbalistJohn Gerard reports having received seeds of the plant from Europe in his 1597 bookHerball, or Generall Historie of Plantes.[34] Nasturtiums were once commonly called "Indian cresses" because they were introduced from the Americas, known popularly then as the Indies, and used like cress as salad ingredients. In his herbal, John Gerard compared the flowers of the "Indian Cress" to those of theforking larkspur (Consolida regalis) of thebuttercup 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 LatineConsolida regalis."[34]
J. R. R. Tolkien commented that an alternative anglicization of "nasturtium" was "nasturtian".[35]
