DAHLIA 



DAHLIA 



449 



All the florets were sterile. D. arborea has never been 

 sufficiently described, but plants have been cultivated 

 for many yt-ars under this name. The tree forms of 

 Dahlias are not sufficiently known. 



AA. Height medium, averaging 3 ft., commonly from 



%-5 ft., rarely exceeding these extremes. 

 B. Lvx. once pinnate: stem not branching from the ba ,: 



habit erect. 



c. Stems not glaucous : rays fertile. 

 D. Ray* of the single fix. not recurved at the margins ; 



of the double fls. never flat, but cupped. 

 rdsea.Cav. (D. variabilix, Desf. ). Fig. 663. Theorigi- 

 nal of practically all the old-fashioned Dahlias, particu- 

 larly the Single, Pompon, Show and Fancy 

 types. It is therefore the parent of the vast 

 majority of the horticultural varieties. Lvs. 

 typically once pinnate, sometimes bipinnate: 

 leaflets ovate, toothed, broader and coarser 

 than in the other species. B.R. 1:55. B.M. 

 1885. This is a wonderfully variable species. 

 Some plants are densely hairy, others scarcely 

 at all. The Ivs. are sometimes bipinnate in 

 parts of plants or throughout an entire plant. 

 In double forms the rays usually have abor- 

 tive pistils. Many garden forms have glau- 

 cous stems. Some authors have doubted 

 whether this species is distinct from D. coc- 

 cinea, but the two types are very distinct, 

 particularly in the garden, although there are 

 intermediate forms in nature. 



DD. Hays of the single fls. with recurved mar- 

 gins; of the double fls. not cupped, but 

 long, flat and pointed, and some at 

 least with recurved margins. 

 Juarezii, Hort. ( />. Yuarezii, Hort. ) . Figs. 

 663, 666. The parent of the pure Cactus Dah- 

 lias. These all originated from one plant, 

 which was flowered in Europe for the first 

 time in 1864, and first pictured in G. C. II. 

 12:433 (1879). F.M. 1879: 383. Gn. 18, p. 589: 

 19:283; 50, p. 236. 



CC. Stems glaucous : rays not fertile. 

 coccinea, Cav. Fig. 667 ; see B. M. 762 

 (1804). Always more slender than D. rosea, 

 with narrower leaflets, and in the wild, at 

 least, dwarf er than the D. rosea. The 

 color range is much smaller, and does not in- 

 clude white or any shade of purple or crim- 

 son. The colors vary from scarlet, through 

 orange to yellow. There are no double forms, 

 and it has been frequently said that this, spe- 

 cies will not hybridize with D. rosea. The 

 named varieties pictured in I.H. 31:515 and 

 533 (1881), which are emphatically declared to 

 be varieties of D. coccinea, are probably gar- 

 den forms of D. rosea. The only characters that cer- 

 tainly distinguish D. coccinea from D. rosea are the 

 glaucous stems and infertile rays of the former, but 

 these characters break down in garden forms. B. M. 

 762. Gn. 19:270. G.C. II. 12:525. 



BB. Lvs. twice pinnate : stems branched from the base: 



habit spreading. 



Merckii, Lehm. (D. glabrata, Lindl.). Fig. 668; 

 confer B.M. 3878 (1841). Height 2-3 ft.: roots much 

 more slender than those of D. rosea: stem and Ivs. 

 wholly devoid of hairs : Ivs. bipinnate: floral bracts 

 linear: fls. typically lilac ; rays pistillate: outer in volu- 

 cral bracts linear. B.R. 26: 29 (1840). Gn. 19: 270 (1881). 

 This is a very distinct garden plant, and is worth 

 growing merely as a foliage plant. Seeds of species 

 gathered from wild plants in Mexico by Pringle have 

 been grown at the Cornell Experiment Station lately. 

 The fine-cut character of the foliage makes it vastly 

 more attractive than the coarse foliage of most of the 

 varieties of D. rosea. Several of these seedlings had 

 beautiful dark red or purple foliage. The plants are 

 much dwarf er and wider spreading than most florists' 

 Dahlias, and show no stem while growing. The branched 

 flowering stems are remarkably long, slender and wiry, 



29 



often rising 2-3 ft. above the foliage. The rays are very 

 short and often roundish, with a short sharp point in- 

 stead of 3 minute teeth. There are no red, yellow or 

 white forms in nature. The roots of this and D. coccinea, 

 being slenderer than those of D. rosea, must be pre- 

 served with greater care during winter. 



D. Zimapani. See Cosmos diversifolius. \V.M. 



PROPAGATION. There are four methods by which 

 Dahlias are propagated : by cuttings (an important 

 commercial method) ; by division of roots (the amateur's 



665. The original Cactus Dahlia 

 Photographed and reduced from the Gardeners' Chronicle, 

 where it was first pictured. 



method ) ; by grafting to perpetuate rare kinds ; and by 

 seeds, to produce new varieties. 



Division of Hoots. This is the easiest and most sat- 

 isfactory to amateurs. As the eyes are not on the 

 tubers, but on the crown to which the tubers are at- 

 tached, care must be taken that each division has at 

 least one eye, otherwise the roots will never grow. It 

 is, therefore, best to start the eyes by placing the roots 

 in a warm, moist place a short time before dividing. 

 The roots are sometimes placed in a hotbed, and shoots 

 grown to considerable size, then set out as plants ; but 

 this plan has many drawbacks, and is not advised. 



Cuttings. This method is used mainly by commercial 

 growers, and though the amateur may propagate plants 

 successfully, the attention a few cuttings would require 

 would be so great that it would be cheaper to buy plants. 

 The roots are planted closely in benches in the green- 

 house early in January, and cuttings are made from the 



