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Viola (plant)

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The genus *Viola* contains a massive variety of flowering plants. These plants are commonly known as violets. They belong to the family Violaceae. This is the largest genus within that family. It includes over 680 different species.

Common Violet
Common Violet

While most species live in the temperate Northern Hemisphere, they grow in many places. You can find them in Hawaii, Australasia, and the Andes. Some are perennial plants that live for many years. Others are annual plants that live for one season. A few even grow as small shrubs.

These plants have very specific physical structures. Some species are acaulescent. This means the foliage and flowers appear to rise directly from the ground. Other species have short stems. In these plants, leaves and flowers grow from the axils of the leaves. This is called axillary growth. Most leaves are heart-shaped or kidney-shaped, which scientists call reniform. Some leaves are linear or palmate. The leaves always have stipules, which are often leaf-like structures.

Viola canina 100
Viola canina 100

The flowers of most *Viola* species are zygomorphic. This term means they have bilateral symmetry. This means if you split the flower down the middle, both sides would match. Each flower usually has five petals. Four petals are upswept or fan-shaped. There is one broad, lobed lower petal that points downward. This petal may be much shorter than the others. Many species have a structure called a spur. This spur can be on the end of each petal or just on the lower petal. In *Viola rostrata*, the spur is very long.

Viola epipsila 5999
Viola epipsila 5999

Inside the flower, the reproductive parts are quite complex. The flowers have five sepals that stay on the plant after blooming. In some species, these sepals actually grow larger after the flower blooms. There are also five free stamens. These stamens have short filaments that press against the ovary. Only the bottom two stamens are calcarate. This means they have nectary spurs that connect to the lower petal. The ovary is superior and contains one cell. This cell has three placentae and many ovules.

Viola pedata
Viola pedata

History helps us understand how we classified these plants. Carl Linnaeus first described the genus in 1753. He originally identified only 19 species.

Linnaeus Viola
Linnaeus Viola

In 1789, Jussieu placed *Viola* in the Cisti family. However, Batsch established a separate family called Violariae in 1802. Most scientists eventually adopted the name Violaceae. This name was proposed by de Candolle and others in the early 1800s. Today, scientists use molecular phylogenetic studies to understand how these species are related. These studies look at DNA to see how plants evolved.

Taxonomists divide the genus into many different sections. The largest section is Andinium. It is found in South America and has about 113 species.

Viola banksii
Viola banksii

Another important group is the Melanium section. This section includes the pansies we see in gardens. In horticulture, a pansy is a large-flowered cultivar. These are often grown annually or biennially from seed.

Some species are famous for their scent. A compound called ionone creates this smell. Interestingly, ionone can temporarily desensitize your nose. This prevents you from smelling the flower until your nerves recover.

Violet candy from Savoie, 2023
Violet candy from Savoie, 2023

The way *Viola* spreads its population is quite energetic. After flowering, the plant produces thick-walled fruit capsules. These capsules contain many seeds. When the capsules dry out, they undergo a process called dehiscence. This means they split open. The capsules can eject seeds with enough force to throw them several meters away.

Akkerviooltje opengesprongen doosvrucht
Akkerviooltje opengesprongen doosvrucht

The seeds are often arillate, meaning they have a specialized outgrowth. They also contain a soft, oily endosperm to help them grow. This process ensures that new plants can establish themselves away from the parent plant.

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🖼️ Images & Media (19)
File:Akkerviooltje opengesprongen doosvrucht.jpg
Akkerviooltje opengesprongen doosvrucht.jpg
File:Linnaeus Viola.png
Linnaeus Viola.png
File:Viola canina 100.jpg
Viola canina 100.jpg
File:Viola biflora Kilpisjarvi 2012-07.jpg
Viola biflora Kilpisjarvi 2012-07.jpg
File:Viola reichei.JPG
Viola reichei.JPG
File:JDCANO Viola Cazorlensis.jpg
JDCANO Viola Cazorlensis.jpg
File:Viola banksii.jpg
Viola banksii.jpg
File:Viola stipularis-La Soufrière-Guadeloupe 1.JPG
Viola stipularis-La Soufrière-Guadeloupe 1.JPG
File:Common Violet.JPG
Common Violet.JPG
File:Viola pedata.jpg
Viola pedata.jpg
File:Viola abyssinica mt kenya 01.jpg
Viola abyssinica mt kenya 01.jpg
File:Viola epipsila 5999.jpg
Viola epipsila 5999.jpg

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