42 MISSOURI BOTANICAL GARDEN BULLETIN 
species “pinnata” because of the winged leaves. Dahlia 
coccinea and D. rosea were later described by him, and the 
seed sent to the various botanical gardens of Europe. 
The first aoa publication to mention the dahlia was 
the “Botanical Magazine” which contained a colored plate 
of D. coccinea, in 1804, The cultivation of the plants spread 
rapidly through the European gardens from that period, 
the doubleness of the flower gradually increasing until the 
large ball-shaped “show” dahlias reached their perfection 
about 1850. om 1860 to 1870 little enthusiasm was ex- 
ressed, but later a great advance in popularity was effected 
be the introduction from Mexico of the cactus-like type, D. 
Juarezti. Its elegance of form, diversity of type, size, and 
delicate coloring gave dahlia culture a new impulse. The 
crossing of this species with the singles has produced a still 
more graceful and acceptable form, the peony-flowered 
dahlia, which now rivals in beauty and popularity the cactus 
In recent years the single dahlias of large size and 
brilliant coloring have caused a revival of interest in that 
class, the collarette and anemone-flowered types adding 
greatly to the already numerous kinds available. 
The first American publication on the dahlia appeared 
in 1839, and the subsequent history of the plant in this 
country closely resembles that of England in the rane 
and waning of its popularit through different periods o 
development. The species which have played an important 
art in the production of the present improved dahlias are 
p rosea, known to the trade as D. variabilis, D. coccinea, 
D. Juarezi, D. imperialis, D. excelsa, D. Merckii, D. gracilis, 
and D. pinnata. Up to the present time approximately 3,000 
varieties have been listed by the leading tradesmen. 
The dahlia is classified in several distinct groups: single, 
anemone, collarette, duplex, cactus, decorative, show, peony, 
pompon, and Tom Thumb. 
1. Single——Open-centered flowers with eight to twelve 
floral rays in one circle, margins often turned down or back. 
2. Anemone.—F lowers with one row of large floral rays 
like single dahlias, but with disk-flowers producing small, 
tubular petals. 
8. Collarette—Open-centered blossoms with not more 
than nine floral rave but with one or more rows of smaller 
rays, usually of a different color, making a collar about the 
4. Duplex.—Semi-double flowers, with center always ex- 
posed on opening of bud, and with petals in more than one 
