448 



DAHLIA 



DAHLIA 



proved. Wild Dahlias, when brought into cultivation, 

 soon grew too tall to be self-supporting. An old-fashioned 

 unbranched Dahlia tied to a large and ugly stake was 

 often a hopeless and helpless object. Many varieties of 

 Dahlias can be made to branch at the ground and be- 

 come self-supporting by successive early pinchings of 



663. A Show Dahlia and its wild progenitor (X%). 



the leading shoots, but some varieties seem to be too 

 firmly set in the old tree-like habit to submit to pinch- 

 ing. In the early days the average height of plants 

 may have been 5 ft. Nowadays 3 ft. is perhaps the 

 average, but the tendency to retain only dwarf forms 

 still continues, and the Dahlia must ultimately be freed 

 from stakes. The main thing is to secure the good 

 flower first and improve the habit la*er, if possible. It 

 is to be hoped that the coarser kinds of foliage will give 

 way to more graceful and attractive forms. The "fern- 

 leaved" type is a much cut and delicate kind. Ami 

 Barillet has handsome dark purple, finely cut foliage. 

 All the above features represent general tendencies 

 which, however, work out very differently in each im- 

 portant case. 



The Dahlia has had one difficulty as peculiar to it- 

 self as the calyx bursting of the Carnation, or the differ- 

 ent values of crown and terminal buds of Chrysanthe- 

 mums. They are often troubled with a "green eye." 

 This is a hard round button in the center of a blossom 

 formed by the inner involucral bracts, which, at that 

 stage, are longer than the unopened rays which they 

 protect. Oftener still, this "green eye " is followed by a 

 yellow center. This "green eye "is still considered to 

 destroy the unity of a flower, and in exhibitions is often 

 surreptitiously removed. The yellow disk can be cut 

 out with a knife and the innermost rays carefully re- 

 placed. A fundamental difficulty associated with this 

 matter is the slowness with which some Dahlias open. 

 The outer rays open first, and in Fig. 663 , where the suc- 

 cessive stages are shown: the outer ones are the most 

 expanded ; then comes a series of cupped rays ; then 

 some that are tightly folded with two creases, and finally 

 the hard green eye. A poor Show Dahlia opens slowly, 

 and shows an eye while the outer rays are tumbling out, 

 withering, or being burned by the sun. A good Show 

 Dahlia opens its tiers in rapid succession, and shows no 

 green eye. 



Literature. As in many other cases, the magazine 

 literature of the Dahlia is the most bulky, and, in some 

 respects, more important than the books on the subject. 



The latest bibliography is that by C. Harman Payne 

 in G.C. III. 21: 329 (1897). There have been about 25 

 books devoted to the Dahlia, many of them pamphlets 

 and cheap cultural manuals. These books were mostly 

 published from 1828 to 1857, with none at all for nearly 

 40 years after that date until 1896, when Lawrence K. 

 Peacock's book, The Dahlia, which is the best American 

 book, made its appearance. The first American treatise 

 was by E. Sayers, published at Boston, 1839, and now 

 forgotten. Many interesting facts came out in 1889, the 

 centennial year of the Dahlia. A report of the National 

 Dahlia Conference is reprinted from the Joxirnal of the 

 Royal Horticultural Society for 1890, but Shirley Hib- 

 berd's statements therein regarding the botany of the 

 Dahlia agree very poorly with Hemsley's revision of 

 the genus in G. C. II. 12 : 437, 524, 557 ( 1879) , which is the 

 latest botanical monograph. 



A. Height tall, tree-like. 

 B. Fls. nodding, 'bell-shaped. 



imperialis, Eoezl. Height 6-18 ft. : stem usually un- 

 branched, knotty, 4-6-angled : Ivs. 2-3-pinnately parted ; 

 leaflets 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, espe- 

 cially at the base: rays sterile or pistillate, lanceolate, 

 sharp-pointed, not 3-toothed at the apex. Gt. 1863: 407. 

 G.C. 1870 : 459 ; II. 12 : 437. B. M. 5813. Gn. 12 : 95 ; 33, 

 p. 527. R.H. 1872:170. A.G. 15:313. Mn. 8: 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 

 cultivated surroundings. This species and the next 

 are mostly cultivated under glass ; the others are grown 

 outdoors in summer, and the roots stored in winter. 



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



exc61sa, Benth. (D. arborea, Regel). Height 20 ft. or 

 more: stem usually unbranched, glaucous, marked with 

 horizontal rings made by the stem-clasping base of the 

 petioles as the lower Ivs. fall away: Ivs. bipinnate, as 

 much as 2% ft. long, 2 ft. wide; leaflets 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, 



664. A semi-double form of Dahlia 

 This is one of many that have been crowded out in the 

 struggle to perfect the Show and Fancy types. 



crimson -pink. Maund, Botanist 2: 88 (1838 ?). G.C. II. 

 19: 80. This was described from a cultivated plant with 

 8 rays in a single row, but with considerably elongated 

 disk fls. It was almost an anemone-flowered type, and 



