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''Viola'' ( and )〔The pronunciation () is the most common one in US English, but US dictionaries also record (less common) use of () and (): (American Heritage Dictionary ), (Merriam-Webster Online Dictionary ). Interestingly, the only pronunciation recorded by the (Compact Oxford English Dictionary ) is () but the only pronunciation recorded by the (Oxford Dictionaries Online ) is ().〕 is a genus of flowering plants in the violet family Violaceae. It is the largest genus in the family, containing between 525 and 600 species.〔Ning, Z. L., et al. (2012). (''Viola jinggangshanensis'' (Violaceae), a new species from Jiangxi, China. ) ''Annales Botanici Fennici'' 49(5) 383-86.〕〔Zhou, J. S., et al. (2008). (''Viola nanlingensis'' (Violaceae), a new species from Guangdong, southern China. ) ''Annales Botanici Fennici'' 45(3) 233-36.〕 Most species are found in the temperate Northern Hemisphere, however some are also found in widely divergent areas such as Hawaii, Australasia, and the Andes. Some ''Viola'' species are perennial plants, some are annual plants, and a few are small shrubs. A large number of species, varieties and cultivars are grown in gardens for their ornamental flowers. In horticulture the term "pansy" is normally used for those multi-coloured, large-flowered cultivars which are raised annually or biennially from seed and used extensively in bedding. The terms "viola" and "violet" are normally reserved for small-flowered annuals or perennials, including the species.〔http://www.americanvioletsociety.org/Species_N_Cultivars/Pansy.htm (Accessed 14 Oct 2008)〕〔http://www.rhs.org.uk/RHSPlantFinder/GenusClass.asp?Genus=Viola (Accessed 14 Oct 2008)〕 ==Description== ''Viola'' typically have heart-shaped, scalloped leaves, though a number have palmate leaves or other shapes. The vast majority of ''Viola'' species are herbaceous, and a substantial number are acaulescent in habit - meaning they lack any noticeable stems and the foliage and flowers appear to rise from the ground; the remaining species have short stems with foliage and flowers produced in the axils of the leaves. The simple leaves of plants with either habit are arranged alternately; the acaulescent species produce basal rosettes. Plants always have leaves with stipules that are often leaf-like. The flowers of the vast majority of the species are zygomorphic with bilateral symmetry. The flowers are formed from five petals; four are upswept or fan-shaped petals with two per side, and there is one broad, lobed lower petal pointing downward. The shape of the petals and placement defines many species, for example, some species have a "spur" on the end of each petal while most have a spur on the lower petal. Solitary flowers end long stalks with a pair of bracteoles. The flowers have 5 sepals that persist after blooming, and in some species the sepals enlarge after blooming. The flowers have five free stamens with short filaments that are oppressed against the ovary, only the lower two stamens have nectary spurs that are inserted on the lowest petal into the spur or a pouch. The flower styles are thickened near the top and the stigmas are head-like, narrowed or often beaked. The flowers have a superior ovary with one cell, which has three placentae, containing many ovules. ''Viola'' are most often spring blooming with chasmogamous flowers with well-developed petals pollinated by insects. Many species also produce self-pollinated cleistogamous flowers in summer and autumn that do not open and lack petals.〔Walters, Dirk R., and David J. Keil. 1996. ''Vascular plant taxonomy''. Dubuque, Iowa: Kendall/Hunt Pub. Co. Page 332.〕 In some species the showy chasmogamous flowers are infertile (e.g.,''Viola papilionacea'').〔( Violet, Common Blue - (‘’Viola papilionacea’’) )〕 After flowering, fruit capsules are produced that split open by way of three valves.〔Cullen, J. 2001. ''Handbook of North European garden plants with keys to families and genera''. Cambridge: Cambridge University Press. Page 345.〕 On drying, the capsules may eject seeds with considerable force to distances of several meters.〔Rendle, Alfred B. 1967. The classification of plants. Vol. II: Dicotyledons. Cambridge at the University Press. (See page 208).〕 The nutlike seeds have straight embryos, flat cotyledons, and soft fleshy endosperm that is oily.〔Cronquist, Arthur. 1981. ''An integrated system of classification of flowering plants''. New York: Columbia University Press. Page 404.〕 The seeds of some species have elaiosomes and are dispersed by ants.〔Sanders, Jack. 2003. The secrets of wildflowers. Guilford, CT: The Globe Pequot Press. (See page 49).〕 Flower colours vary in the genus, ranging from violet, through various shades of blue, yellow, white, and cream, whilst some types are bicolored, often blue and yellow. Flowering is often profuse, and may last for much of the spring and summer. One quirk of some ''Viola'' is the elusive scent of their flowers; along with terpenes, a major component of the scent is a ketone compound called ionone, which temporarily desensitises the receptors of the nose, thus preventing any further scent being detected from the flower until the nerves recover. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Viola (plant)」の詳細全文を読む スポンサード リンク
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