952 



DAHLIA 



DAHLIA 



receptacle plane, bearing chaffy scales; rays spreading, 

 entire or minutely 3-5-dentate: fr. oblong or obovate, 

 strongly compressed on the back, rounded at the apex, 

 obscurely 2-toothed or entirely bald. Probably 10 or 

 12 species, in the higher parts of Mex., some of them 

 now much modified by cult., and the domesticated 

 forms often difficult of systematic study. The nomen- 

 clature of the group is confused because systematists 

 are not agreed on the rank to be given to forms that 

 have received independent names. Voss (Blumen- 

 gartnerei) combines the three species of Cavanilles, 

 D. pinnata, D. coccinea, and D. rosea, all under the name 

 D. pinnata. His arrangement is as follows : D. pinnata, 

 Cav.; var. coccinea, Voss (D. coccinea, Cav. D. rosea, 

 Cav., in part. D. frustranea, DC. D. crocea, Poir. D. 

 bidentifolia B,nd D. mexicana, Hort.); var. gracilis, 

 Voss (D. gracilis, Ort.); var. Cervantesii, Voss (D. 

 Cervantesii, Lag.); var. variabilis, Voss (D. variabilis, 

 Desf. D. rosea, Cav., in part. D. sambucifolia, Salisb. 

 D. superflua, Ait. D. purpurea, Poir.). It seems to 

 be well, however, to keep D. rosea and D. coccinea dis- 

 tinct, and perhaps also D. pinnata; and this is the 

 method adopted for the present treatment. Of the three 

 Cavanillesian names, D. pinnata has priority. 



A. Plant very tall, tree-like. 

 B. Fls. nodding, bell-shaped. 



imperialis, Roezl. Height 6-18 ft.: sts. usually many 

 from one base, mostly unbranched, knotty, 4-6-angled, 

 usually dying to the ground in winter in S. Calif.: 

 Ivs. 2-3-pinnately parted; Ifts. ovate, narrowed at the 

 base, acuminate, toothed, with a few short scattered 

 soft hairs: fls. nodding, 4-7 in. across, white, more or 

 less tinged with blood-red, especially at the base; rays 

 sterile or pistillate, lanceolate, sharp-pointed, not 

 3-toothed at the apex. Gt. 1863:407; 56, p. 22. G.C. 

 1870:459; II. 12:437; III. 34:178. B.M. 5813. Gn. 

 12:352; 33, p. 527; 61, p. 40. R.H. 1872:170; 1911, pp. 

 62-3. A.G. 15:313. Mn. 8, p. 61. As few conservatories 

 can make room for so large a plant, it is common to 

 graft this species on dwarf varieties of D. rosea. The 

 inflated and pointed fl.-buds (3-4 in. long) are very 

 characteristic. It is not known whether the original 

 plant collected by Roezl was found in wild or cult, 

 surroundings. This species and the next are mostly 

 cult, under glass if cult, at the N., but this species 

 thrives in the open in Cent. Calif.; the others are 

 grown outdoors in summer, and the roots stored in 

 winter. Hybrids are reported between this species and 

 D. excelsa. 



BB. Fls. erect, not bell-shaped, but opening out flat. 



excelsa, Benth. (D. arbbrea, Regel). Height to 20 

 ft. or more: sts. several from same base, usually 



unbranched, glaucous, 

 marked with horizon- 

 tal rings made by the 

 stem-clasping base of 

 the petioles as the 

 lower Ivs. fall away, 

 becoming woody for 

 several feet in mild 

 climates: Ivs. bipin- 

 nate, as much as 2}^ 

 ft. long, 2 ft. wide; Ifts. 

 as many as 25, ovate, 

 those of the upper Ivs. 

 often contracted at 

 the base, acuminate, 

 toothed, pale green 

 beneath, with a few short scattered hairs or none: fls. 

 4^ in. across, dilute purple, crimson-pink. G.C. II. 

 19:80; III. 27:85. This species was described from a 

 cult, plant with 8 rays in a single row, but with 

 considerably elongated disk-fls. It was almost an 

 anemone-fid, type, and all the florets were sterile. D. 



1205. Clustered roots of the 

 garden dahlia. 



arborea has never been sufficiently described as a 

 botanical species, but plants have been cult, for many 

 years under this name. Var. anemonaefldra, Hort. 

 Disk of lilac or yellow tubular florets; rays flat. 



AA. Plant medium, averaging 3 ft., commonly from 2-5 



ft., rarely exceeding these extremes. 

 B. Lvs. once pinnate: st. not branching from the base: 



habit erect. 



c. St. usually not glaucous: rays fertile. 

 D. Rays of the single fls. not recurved at the margins; 



of the double fls. never flat, but cupped. 

 rosea, Cav. (D. variabilis, Desf. D. Bdrkerise and 

 D. Royledna, Know). & Westc.? D. superflua, Ait. 



1206. Dahlia rosea (or D. variabilis). (XK) 



D. purpurea, Poir. D. nana, Andr. D. crocdta, Lag. 

 D. corondta, Hort.). Fig. 1206. Lvs. typically once 

 pinnate, sometimes biplnnate; Ifts. ovate, toothed, 

 broader and coarser than in the other species. B.R. 

 55. B.M. 1885. The original of practically all the 

 old-fashioned dahlias, particularly the Single, Pompon, 

 Show and Fancy types. It is therefore the parent of 

 the vast majority of the horticultural varieties. This 

 is a wonderfully variable species. Some plants are 

 densely hairy, others scarcely at all. The Ivs. are some- 

 times bipinnate in parts of plants or throughout an 

 entire plant. In double forms the rays usually have 

 abortive pistils. Many garden forms have glaucous 

 sts. Some authors have doubted whether this species 

 is distinct from D. coccinea, but the two types are very 

 different in the garden, although there are intermediate 

 forms in nature. 



DD. Rays of the single fls. with recurved margins; of 

 the double fls. not cupped, but long, flat and pointed, 

 and some at least with recurved margins. 

 Juarezii, Hort. (D. Yuarezii, Hort.). CACTUS 



DAHLIA. Fig. 1207. Distinct in the bloom: heads bril- 



