Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

VIOLET

Online Encyclopedia
Originally appearing in Volume V28, Page 102 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

VIOLET . The violets comprise a large botanical genus (See also:

Viol)—in which more than 200 See also:species have been described —found principally in temperate or See also:mountain regions of the See also:northern hemisphere; they also occur in mountainous districts of See also:South See also:America and South and Tropical See also:Africa, while a few are found in See also:Australasia. The species are mostly See also:low-growing herbs with alternate leaves provided with large leafy stipules (fig. I). The See also:flowers, which are solitary, or rarely in pairs, at the end of slender axillary See also:flower-stalks, are very irregular in See also:form, with five sepals prolonged at the See also:base, and five petals, the lowest one larger than the others and with a See also:spur, in which collects the See also:honey secreted by the spurs of the two adjoining stamens. The five anthers are remarkable for the coloured processes which extend beyond the anther cells and form a sort of See also:cone around the See also:style (fig. 2). The ovary is See also:superior and one-celled, with three parietal placentas and numerous ovules; it bears a single style, which ends in a dilated or See also:hood-like stigma (fig. 3). The See also:fruit is a See also:capsule bursting loculicidally,i.e. through the centre of each of the three valves. By the contraction of the valves the small smooth seeds, which form a See also:row down the centre, are shot out to some little distance from the See also:parent plant. The irregular construction of the flower is connected with fertilization by See also:insect agency.

To reach the honey in the spur of the flower, the insect must thrust its See also:

proboscis into the flower See also:close under the globular See also:head of the stigma. This lies in the anterior See also:part of a groove fringed with hairs on the inferior petal. The anthers See also:shed their See also:pollen into this groove, either of themselves or when the See also:pistil is shaken by the insertion of the See also:bee's proboscis. The proboscis, passing down this groove to the spur, becomes dusted with pollen; as it. is See also:drawn back, it presses up the See also:lip-like See also:valve of the stigma so that no pollen can enter the stigmatic chamber; but as it enters the next flower it leaves some pollen on the upper See also:surface of the valve, and thus See also:cross-fertilization is effected. In the sweet violet, V. odorata and other species, inconspicuous permanently closed or "cleistogamic" flowers (fig. 4) occur of a greenish See also:colour, so that they offer no attractions to insect visitors and their form is correspondingly See also:regular. The anthers are so situated that the pollen on escaping comes into contact with the stigma; in such flowers self-fertilization is compulsory and very effectual, as seeds in profusion are produced. Several species of See also:Viola are native to See also:Great See also:Britain. Viola See also:canina (fig. 5) is the See also:dog violet, many forms or subspecies of which are recognized; V. odorata, sweet violet, is highly prized for its fragrance, and in cultivation numerous varieties have originated. The Neapolitan or See also:Parma violet (See also:var. pallida plena) is a form with very sweet-scented, See also:double, See also:pale See also:lavender flowers; var. sulphurea has shining deep See also:green leaves and See also:lemon-yellow flowers, deeper yellow in the centre, and with a pale-violet spur. Sweet violets like a See also:rich, fairly heavy See also:soil, with a See also:north or north-See also:west aspect if possible; F?G.

4.-CleistogamicFlower of Viola sylvatica. I. Flower. 2. Flower more highly magnified and cut open. a, anther; s, pistil; st, style; v, stigmatic surface. they are readily increased by dividing the crowns after flowering. Other species known in gardens are: V. altaica, flowers yellow or i. Floral See also:

diagram of Viola, showing arrangement of parts in See also:horizontal See also:plan. b, pair of bracteoles below the flower; s, sepals; p, petals; st, stamens; o, ovary. 2. Fruit, split open. violet with yellow See also:eye; V. biflora, a See also:pretty little species 3–4 in. high with small yellow flowers, the large petal being streaked with See also:black; V. calcarata, flowers See also:light See also:blue or See also:white, or yellow in var. "See also:lava; V. cornuta, flowers pale blue—there are a few See also:good varieties of this, including one with white flowers; V. cucullata, a See also:free-flowering See also:American species with violet-blue or See also:purple flowers; V.

Munbyana, a native of See also:

Algeria, with large violet or yellow flowers; V. pedata, the See also:bird's-See also:foot violet, with pedately divided leaves and usually See also:bright blue flowers; V. rothomagensis, a native of western See also:Europe, with flowers bright blue striped with black, and sometimes called the See also:Rouen violet; and V. suavis, a native of See also:Asia See also:Minor, the See also:Russian violet, with pale-blue sweet-scented flowers. The See also:garden pansies or heartseases are derivatives from V. tricolor, a cornfield See also:weed, or V. al:aice, a native of the See also:Altai mountains. (See See also:PANSY.) " Bedding violas," which differ from pansies in some slight technical details, have been raised from V. cornuta and V. lutea by See also:crossing with the show pansies. The application of an infusion of violet leaves was at one See also:time believed to have the See also:power of reducing the See also:size of cancerous growths, but its use is now discredited.

End of Article: VIOLET

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
VIOLA [Fr. viole, Ger. Bratsche, Ital. viola, alto]... 		[next]
VIOLIN

Site © 2006 - Net Industries