Online Encyclopedia

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

DAHLIA

Online Encyclopedia
Originally appearing in Volume V07, Page 732 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!

DAHLIA , a genus of herbaceous See also:

plants of the natural See also:order See also:Compositae, so called after Dr See also:Dahl, a See also:pupil of See also:Linnaeus. The genus contains about nine See also:species indigenous in the high sandy plains of See also:Mexico. The dahlia was first introduced into See also:Britain from See also:Spain in 1789 by the marchioness of See also:Bute. The species was probably D. variabilis, whence by far the See also:majority of the forms now See also:common have originated. The See also:flowers, at the See also:time of the first introduction of the plant, were single, with a yellow disk and dull See also:scarlet rays; under cultivation since the beginning of the 19th See also:century in See also:France and See also:England, flowers of numerous brilliant hues have been produced. The See also:flower has been modified also from a See also:flat to a globular shape, and the arrangement of theflorets has been rendered quite distinct in the See also:ranunculus and See also:anemone-like kinds. The See also:ordinary natural height of the dahlia is about 7 or 8 ft., but one.of the See also:dwarf races grows to only 18 in. With changes in the flower, changes in the shape of the See also:seed have been brought about by cultivation; varieties of the plant have been produced which require more moisture than others; and the See also:period of flowering has been made considerably earlier. In 18o8 dahlias were described as flowering from See also:September to See also:November, but some of the dwarf varieties at See also:present grown are in full blossom in the See also:middle of See also:June. The large number of varieties may be classed as under the following heads: (I) Single dahlias. These have been derived from D. coccinea; they have a disk of tubular florets surrounded by the large showy See also:ray florets. (2) Show dahlias, large and See also:double with flowers self-coloured or See also:pale-coloured and edged or tipped with a darker See also:colour.

(3) See also:

Fancy dahlias, resembling the show but having the florets striped or tipped with a second tint. (4) Bouquet or Pompon dahlias, with much smaller double flowers of various See also:colours. (5) See also:Cactus dahlias, derived from D. Juarezi, a See also:form which has given rise to a beautiful See also:race with pointed starry flowers. (6) See also:Paeony flowered dahlias, a new but not See also:pretty race, with large floppy heads, broad florets and several disk florets in centre. New varieties are procured from seed, which should be sown in pots or pans towards the end of See also:March, and placed in a hotbed or propagating See also:pit, the See also:young plants being pricked off into pots or boxes, and gradually hardened off for planting out in June; they will flower the same See also:season if the summer is a genial one. The older varieties are propagated by dividing the large tuberous roots, in doing which care must be taken to leave an See also:eye to each portion of tuber, otherwise it will not grow. Rare varieties are sometimes grafted on the roots of others. The best and most See also:general mode of See also:propagation is by cuttings, to obtain which, the old tubers are placed in See also:heat in See also:February, and as the young shoots, which rise freely from them, attain the height of 3 in., they are taken off with a See also:heel, and planted singly in small pots filled with See also:fine sandy See also:soil, and plunged in a moderate heat: They See also:root speedily, and are then transferred to larger pots in See also:light See also:rich soil, and their growth encouraged until the planting-out season arrives, about the middle of June See also:north of the See also:Thames: Dahlias succeed best in an open situation, and in rich deep See also:loam, but there is scarcely any See also:garden soil in which they will not thrive, if it is manured. For the See also:production of fine show flowers the ground must be deeply trenched, and well manured annually. The branches as well as the blossoms require a considerable but judicious amount of thinning; they also need shading in some cases. The plants should be protected from See also:cold winds, and when watered the whole of the foliage should be wetted.

They may stand singly like common border flowers, but have the most imposing See also:

appearance when seen in masses arranged according to their height. Florists usually devote a See also:plot of ground to them, and plant them in lines 5 to 10 ft. apart. This is done about the beginning of June, sheltering them if necessary from See also:late frosts by inverted pots or in some other convenient way. Old roots often throw up a multitude of stems, which render thinning necessary. As the plants increase in height, they are furnished with strong stakes, to secure them from high winds. Dahlias flower on till they are interrupted by See also:frost in autumn. The roots are then taken up, dried, and stored in a cellar, or some other See also:place where they may be secure from frost and moisture. See also:Ear-wigs are very destructive, eating out the young buds and florets. Small flower-pots See also:half filled with dry See also:moss and inverted on stakes placed among the branches, form a useful See also:trap.

End of Article: DAHLIA

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]
DAHLGREN, KARL FREDRIK (1791-1844)
[next]
DAHLMANN, FRIEDRICH CHRISTOPH (1785-186o)