DAflLIA 



THE BULB BOOK 



toAHtU 



ft. and more high and has brilliant 

 scarlet flower - heads, the florets of 

 which overlap and vary in length. 

 It was introduced from Mexico in 

 1872, and when exhibited in London 

 in September 1879 attracted little or 

 no attention. As the parent of the 

 renowned " Cactus " Dahlias, it has 

 since that time made rapid strides in 

 public favour, and has given rise to 

 innumerable beautiful varieties. 



D. Mercki (D. glabrata). — A beauti- 

 ful species 2 to 4 ft. high, having 

 pinnate or twice-pinnate leaves with 

 toothed margins, and rather small 

 white and yellow or lilac and yellow 

 flower-heads. The variety Decais- 

 neama has purple flower-heads with 

 yellow centres. {Bot. Mag. t. 3878 ; 

 Rev.Hort. 1864, p. 31.) 



This species has given rise to many 

 garden forms. 



D. variabilis {D. crocata ; D. super- 

 flua). — The typical wild species has 

 branching stems, pinnately divided 

 leaves witTi more or less " winged " 

 leaf-stalks, and flower-heads varying 

 in colour ; the ray-florets, however, 

 being generally scarlet, the disc ones 

 yellow. 



This species is regarded as the first 

 one introduced from Mexico, not so 

 much for its beauty as a decorative 

 garden plant, but for its tuberous 

 roots, which it was thought would 

 rival the potato as an article of 

 diet. 



D. viridiflora. — This is a curiosity 

 evolved by cultural selection. Its 

 peculiarity consists in having the 

 green bracts of the involucre increas- 

 ing at the expense of the coloured 

 ray-florets, the whole flower - head 

 resembling a small green pompon 

 rose. 



D. Zimapani {Cosmos diversifolius). 

 — This is commonly known as the 

 "Black Dahlia." It grows 12 to 18 

 ins. high, its deep green leaves being 



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cut into five to seven entire or slightly 

 toothed segments. The flower-heads 

 are deep violet or almost blackish- 

 purple in colour, and appear from 

 July to October. The variety atro- 

 purpurea is even deeper in colour. 



GrAEDBN DaHLIAS. 



During the past century wonderful 

 changes have been wrought in the 

 Dahlia. It adapted itself so readily 

 to our climate and displayed such an 

 early tendency to variation, that 

 gardeners were not slow to take ad- 

 vantage of its peculiarities. Of the 

 species enumerated above, only D. 

 coccinea, D. Mercki, D. variabilis, and 

 D. Juarezi appear to be involved in 

 the creation of the modern Dahlia. 

 Crossing and intercrossing has been 

 carried on unceasingly for many years, 

 with the result that there are now 

 innumerable varieties suitable for 

 garden decoration. These are divided 

 into several more or less distinctive 

 groups, amongst which may be men- 

 tioned : — 



1. Single Dahlias. — Although at 

 one time greatly neglected, owing to 

 the development of "double" forms, 

 the single Dahlias now find many 

 admirers, owing to their graceful habit, 

 quantity and beauty of blossom, and 

 easiness of culture. Special varieties 

 can always be kept pure and distinct 

 by propagation of the shoots or 

 division of the tuberous roots; or 

 large numbers of new forms may be 

 raised easily from seeds each year. 



Closely related to these are what 

 are known as " Tom Thumb " Dahlias, 

 so called owing to their dwarf stature. 

 They have not gained in popularity, 

 and are rarely grown. 



2. Pompon, Bouquet, or Bedding 

 Dahlias. — This is a free-flowering 

 class, having perfectly shaped and 

 symmetrical "double" flower-heads, 

 usually borne well above the foliage, 



