Viola (most commonly pronounced /vaɪ.ˈoʊ.lə/ in US English and /ˈviː.ə.lə/ in UK English[1]) is a genus In biology, a genus is a low-level taxonomic rank (a taxon) used in the classification of living and fossil organisms, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender", cognate with Greek: γένος – genos, "race, stock, kin" of flowering plants The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Together with gymnosperms, they are the only extant groups of seed-producing plants, but they can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers, in the violet family Violaceae Violaceae is a family of flowering plants consisting of about 800 species in 21 genera. It takes its name from the genus Viola, the violets and pansies, with around 400–500 species distributed around the world. Most species are found in the temperate Northern Hemisphere The Northern Hemisphere is the half of a planet that is north of equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator. Earth's northern hemisphere contains most of its land area and most of its human population, however viola species (commonly called violets, pansies or heartsease) are also found in widely divergent areas such as Hawaii The state encompasses nearly the entire volcanic Hawaiian Island chain, which comprises hundreds of islands spread over 1,500 miles . At the southeastern end of the archipelago, the eight "main islands" are (from the northwest to southeast) Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and Hawaiʻi. The last is by, Australasia Australasia is a region of Oceania: Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes . He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia (to the east) and the, and the Andes The Andes are the world's longest continental mountain range. It is a continuous chain of highland along the western coast of South America. The range is over 7,000 km long, 200 km (120 mi) to 700 km (430 mi) wide (widest between 18° to 20°S latitude), and of an average height of about 4,000 m (13,000 ft) in South America South America is the southern continent of America, situated in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest.

Most Viola species are tiny perennial plants A perennial plant or perennial is a plant that lives for more than two years. When used by gardeners or horticulturalists, applies specifically to winter hardy perennial herbaceous plants. Scientifically, woody plants like shrubs and trees are also perennial in their habit, some are annual plants An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed. Some seedless plants can also be considered annuals even though they do not grow a flower, and a few are small shrubs A shrub or bush is distinguished from a tree by its multiple stems and lower height, usually less than 5–6 m tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience. Small, low shrubs such as lavender, periwinkle and thyme are often termed subshrubs. A number of species are grown for their ornamental flowers in borders and rock gardens; the garden pansy The pansy or pansy violets are a large group of hybrid plants cultivated as garden flowers. Pansies are derived from Viola species Viola tricolor hybridized with other viola species, these hybrids are referred to as Viola × wittrockiana or less commonly Viola tricolor hortensis. The name "pansy" also appears as part of the common name in particular is an extensively used spring and autumn/winter bedding and pot plant. Viola and violetta are terms used by gardeners and generally in horticulture Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic engineering, plant biochemistry, and plant physiology for neat, small-flowered hybrid plants intermediate in size between pansies and violets.[2][3]

Contents

Description

Viola species typically have heart-shaped, scalloped leaves In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. As an evolutionary trait, the flatness of leaves works to expose the chloroplasts to more light and to increase the absorption of carbon dioxide at the expense of water loss. In the Devonian period, when carbon, though a number have palmate leaves or other shapes. The vast majority of Viola species are herbaceous A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground. A herbaceous plant may be annual, biennial or perennial, 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.

Opened seed capsule, showing the seeds A viola cultivar A cultivar is a cultivated variety of a plant that has been deliberately selected for specific desirable characteristics . When propagated correctly, the plants of a particular cultivar retain their special characteristics showing the large round flowers and the novel coloration that has been achieved through breeding.

The flowers A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds. The process begins with pollination, is followed by fertilization, leading to the formation and dispersal of the seeds. For of the vast majority of the species are zygomorphic with bilateral symmetry Symmetry in biology is the balanced distribution of duplicate body parts or shapes. The body plans of most multicellular organisms exhibit some form of symmetry, either radial symmetry or bilateral symmetry or "spherical symmetry". A small minority exhibit no 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 Viola 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 persistent 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.

After flowering, fruit capsules are produced that split open by way of three valves.[4] Viola flowers 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.[5] The nutlike seeds have straight embryos, flat cotyledons, and soft fleshy endosperm that is oily.[6] The seeds are often spread by ants.

Flower colours Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of vary in the genus, ranging from violet As the name of a color, violet is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nm when indigo is recognized as a distinct color, or more commonly 380–450 nm (this is a spectral color). Second, violet may refer to a shade of purple, that is, a mixture of, as their common name suggests, through various shades of blue, yellow, white, and cream, whilst some types are bicolored, often blue and yellow. Many cultivars A cultivar is a cultivated variety of a plant that has been deliberately selected for specific desirable characteristics . When propagated correctly, the plants of a particular cultivar retain their special characteristics and hybrids In biology and specifically genetics, hybrid has several meanings, all referring to the offspring of sexual reproduction have been bred in a greater spectrum of colours. 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 Terpenes are a large and varied class of hydrocarbons, produced primarily by a wide variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium, a major component of the scent is a ketone In organic chemistry, a ketone is a compound with the structure RC(=O)R', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group (C=O) bonded to two other carbon atoms. Acetone is the simplest example of a ketone, and in fact the word ketone derives its name from Aketon, the German word for acetone compound called ionone The ionones are a series of closely related chemical substances that are part of a group of compounds known as rose ketones, which also includes damascones and damascenones. Ionones are aroma compounds found in a variety of essential oils, including rose oil. beta-Ionone is a significant contributor to the aroma of roses, despite its relatively, which temporarily desensitises the receptors An olfactory receptor neuron, also called an olfactory sensory neuron, (OSN) is the primary transduction cell in the olfactory system of the nose, thus preventing any further scent being detected from the flower until the nerves recover.

Selected species

Wikimedia Commons has media related to: Viola (Violaceae)
Viola odorata

See List of Viola species for a more complete list.

Note: Neither Saintpaulia ("African violets") nor Erythronium dens-canis ("dogtooth violets") are related to the true Viola.

The genus includes dog violets Dog violet is the common name for various species of the plant genus Viola with unscented flowers. The term arose to differentiate them from the scented sweet violet. Species so named include:, a group of scentless species which are the most common viola in many areas, sweet violet Viola odorata (named from its sweet scent), and many other species whose common name includes the word "violet". Several species are known as pansies, including the yellow pansy The Yellow Pansy is a common and attractive wildflower of coastal regions of California and Baja California. It is also known as the California Golden Violet, or as the Johnny Jump Up, though the latter name is more usually associated with the introduced Heartsease, Viola tricolor of the Pacific The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east coasts.

Common blue violet Viola sororia Viola sororia, also known as the Common Blue Violet, is a stemless herbaceous perennial plant that is native to eastern North America. It is known by a number of common names including; Common Meadow Violet, Purple Violet, Woolly Blue Violet, Hooded Violet and Wood Violet is the state flower Categories: Lists of flowers | United States state insignia | States of the United States related lists of Wisconsin The word Wisconsin has its origins in the name given to the Wisconsin River by one of the Algonquian speaking American Indian groups living in the region at the time of European contact. French explorer Jacques Marquette was the first European to reach the Wisconsin River and record its name, arriving in 1673 and calling the river Meskousing in, Rhode Island The State of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island ( /ˌroʊd ˈaɪlɨnd/ or /rɵˈdaɪlɨnd/), is a state in the New England region of the United States. It is the smallest U.S. state by area. Rhode Island borders Connecticut to the west and Massachusetts to the north and east, and it shares a water, Illinois In the 1810s settlers began arriving from Kentucky; Illinois achieved statehood in 1818.Chicago was founded in the 1830s on the banks of the Chicago River, one of the few natural harbors on southern Lake Michigan. Railroads and John Deere's invention of the self-scouring steel plow turned Illinois' rich prairie into some of the world's most, and New Jersey The area was inhabited by Native Americans for more than 2,800 years, with historical tribes such as the Lenape along the coast. In the early 17th century, the Dutch and the Swedes made the first European settlements. The English later seized control of the region, naming it the Province of New Jersey. It was granted as a colony to Sir George.

Australia is home to a number of Viola species, including Viola hederacea, Viola betonicifolia and Viola banksii, first collected by Joseph Banks Sir Joseph Banks, 1st Baronet, GCB, PRS was an English naturalist, botanist and patron of the natural sciences. He took part in Captain James Cook's first great voyage (1768–1771). Banks is credited with the introduction to the Western world of eucalyptus, acacia, mimosa, and the genus named after him, Banksia. Approximately 80 species of plants and Daniel Solander Solander was born in Piteå, Norrland, Sweden and was the son of a Lutheran principal. He enrolled at Uppsala University in July 1750 and studied languages and the humanities. The professor of botany was the celebrated Carolus Linnaeus who was soon impressed by young Solander's ability and accordingly persuaded his father to let him study natural on the Cook Captain James Cook FRS RN was a British explorer, navigator and cartographer, ultimately rising to the rank of Captain in the Royal Navy. Cook was the first to map Newfoundland prior to making three voyages to the Pacific Ocean during which he achieved the first European contact with the eastern coastline of Australia and the Hawaiian Islands as voyage to Botany Bay Botany Bay is a bay in Sydney, New South Wales, a few kilometres south of the Sydney central business district. The Cooks River and the Georges River are the two major tributaries that flow into the bay. Two runways of Sydney Airport extend into the bay.

The modern garden pansy The pansy or pansy violets are a large group of hybrid plants cultivated as garden flowers. Pansies are derived from Viola species Viola tricolor hybridized with other viola species, these hybrids are referred to as Viola × wittrockiana or less commonly Viola tricolor hortensis. The name "pansy" also appears as part of the common name (V. × wittrockiana) is a plant of complex hybrid In biology and specifically genetics, hybrid has several meanings, all referring to the offspring of sexual reproduction origin involving at least three species, V. tricolor Heartsease is a common European wild flower, growing as an annual or short-lived perennial. It has been introduced into North America, where it has spread widely, and is known as the Johnny Jump Up (though this name is also applied to similar species such as the Yellow Pansy). It is the progenitor of the cultivated Pansy, and is therefore (wild pansy or heartsease), V. altaica and V. lutea (mountain pansy).

Horticultural uses

Species and cultivars

Cultivars of Viola cornuta, Viola cucullata, Viola odorata, are commonly grown from seed. Other species often grown include Viola labradorica, Viola pedata and Viola rotundifolia.[7]

Bedding plants

The plants known to gardeners as "violas" are common bedding and pot plants world wide. In 2005 in the United States, violas (including pansies) were one of the top three bedding plant crops and 111 million dollars worth of flats of violas were produced for the bedding flower market.[8] Pansies and violas used for bedding are generally raised from seed, and F1 hybrid F1 hybrid is a term used in genetics and selective breeding. F1 stands for Filial 1, the first filial generation seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types. The term is sometimes written with a subscript, as F1 hybrid. The offspring of distinctly different parental types produce a new, seed strains have been developed which produce compact plants of reasonably consistent flower colouring and appearance. Bedding plants are usually discarded after one growing season.

Perennial cultivars

There are hundreds of perennial viola and violetta cultivars A cultivar is a cultivated variety of a plant that has been deliberately selected for specific desirable characteristics . When propagated correctly, the plants of a particular cultivar retain their special characteristics; many of these do not "come true" from seed and therefore have to be propagated from cuttings. Violettas can be distinguished from violas by the lack of ray markings on their petals.[2] A few popular examples include: [9]

Weed control

Not all violets are desired, and wild violets function as a weed in North American lawns. Wild violets are a problem in shady fescue Festuce is a genus of about 300 species of perennial tufted grasses, belonging to the grass family Poaceae (subfamily Pooideae). The genus has a cosmopolitan distribution, although the majority of the species are found in cool temperate areas, such as the transition zone and Canada. The genus is closely related to ryegrass (Lolium), and recent lawns in North America. Violets thrive in the part/full shade and are not susceptible to most herbicides used to kill common lawn weeds. Triclopyr Triclopyr is a systemic, foliar herbicide in the pyridine group. It is used to control broadleaf weeds while leaving grasses and conifers unaffected, a weedkiller, has been found to be an effective method of controlling wild violets in fescue Festuce is a genus of about 300 species of perennial tufted grasses, belonging to the grass family Poaceae (subfamily Pooideae). The genus has a cosmopolitan distribution, although the majority of the species are found in cool temperate areas, such as the transition zone and Canada. The genus is closely related to ryegrass (Lolium), and recent lawns.

Other uses

Culinary

When newly opened, Viola flowers may be used to decorate salads or in stuffings for poultry or fish. Soufflés, cream and similar desserts can be flavoured with essence of Viola flowers. The young leaves are edible raw or cooked as a somewhat bland leaf vegetable Leaf vegetables, also called potherbs, green vegetables, greens, or leafy greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. Although they come from a very wide variety of plants, most share a great deal with other leaf vegetables in nutrition and cooking methods. The flowers and leaves of the cultivar 'Rebecca', one of the Violetta violets, has a distinct vanilla flavor with hints of wintergreen, however, that is quite delicious in salads.

A candied violet or crystallized violet is a flower, usually of Viola odorata, preserved by a coating of egg white and crystallised sugar. Alternately, hot syrup is poured over the fresh flower (or the flower is immersed in the syrup) and stirred until the sugar recrystallizes and has dried. This method is still used for rose petals and was applied to orange flowers in the past (when almonds or orange peel are treated this way they are called pralines). Candied violets are still made commercially at Toulouse, France, where they are known as violettes de Toulouse. They are used as decorating or included in aromatic desserts.

The French are also known for their violet syrup, most commonly made from an extract of violets. In the United States, this French violet syrup is used to make violet scones and marshmallows.

Viola essence flavours the liqueurs Creme Yvette, Creme de Violette, and Parfait d'Amour. It is also used in Parma Violets confectionery.

Medicinal

The flowers, leaves and roots of various Viola species are used for medicinal purposes, being rich in vitamins A and C. They also contain a type of antioxidant called an anthocyanin. Viola flowers are also used to make an herbal tea that is used in Chinese herbal medicine.

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