DECEMBER 17, 1897.] 
even pale yellow flowers. In 1850 the 
Dahlia appears to have reached the height 
of its popularity, after which date it began 
to decline until the year 1870, when the 
Dahlia Society founded in that year brought 
about a revival of interest in the plant. In 
1872 additional interest was aroused in the 
Dahlia by the introduction of Dahlia 
Juarezii, the Cactus Dahlia said to have 
been obtained from Mexico by a Dutch 
nurseryman, Donkelaar. The organization 
of the American Dahlia Society within the 
last two years has added much to the re- 
awakened interest in the plant. 
As early as 1841 one English dealer had 
over twelve hundred varieties. This shows 
the wonderful variability of the plant, 
which had been in cultivation practically 
only twenty-seven years. This, however, 
is not surprising, when we take into con- 
sideration the range of variation of the 
plant in a state of nature. While visiting 
the Valley of Mexico last summer the 
writer had the opportunity, as well as the 
privilege, of botanizing with the veteran 
botanist and collector, Mr. C. G. Pringle. 
The slopes of the southern range of moun- 
tains known as the Sierra de Ajusco were 
visited. The Dahlias were found growing 
in the greatest profusion on the lava beds, 
known locally as the Pedrigal, literally the 
Stony Place. Acres and acres of the Pedri- 
gal in the latter part of August are one 
mass of color of the most varied hues and 
shades. As the train of the Mexico, Cuer- 
nayaca and Pacific Railroad carries you up 
from Contreras, at the foot of the Sierra de 
Ajusco, toward the top, where the Valley of 
Mexico lies spread out before you as a most 
pleasing panorama, you are carried up 
through woods that are a wild Dahlia 
garden—masses and masses of flaming 
blooms of three species of Dahlia in many 
‘distinct colors. Here areassociated within 
a small area many beautiful plants with 
showy flowers, Bouvardias, Senecios, Stevias 
SCIENCE. 
909 
and the three species of Dahlia, viz: Dahlia 
coccinea, Dahlia variabilis and Dahlia Merckii. 
Dahlia coccinea, Dahlia variabilis and Dahlia 
Merck are three of the most common and 
best known Dahlias which grow in Mexico. 
Of these Dahlia coccinea has the more 
northerly and by far the most extensive 
distribution. From the Oordilleras of 
Chihuahua, within 200 miles of the United 
States boundary, it ranges southward 
through the mountains to Jalisco and the 
Valley of Mexico.* Dahlia variabilis is 
confined to the region around, including 
“the Valley of Mexico. It is a most striking 
plant, growing from 5 to 6 feet tall, and 
bearing flowers ranging in color from pur- 
ple to sulphur-yellow through the follow- 
ing gradations : lavender-purple, heliotrope, 
heliotrope-yellow (various shades of lighter 
and lighter hue approaching yellow) sul- 
phur-yellow. The heads of which the ray 
florets are colored heliotrope-yellow are in 
reality of an heliotrope color, the bases of 
the ligulate corolla being of a yellow color 
shading off into heliotrope. They are 
broad (1 inch), long (2 inches) and ovate 
spatulate. 
Likewise, Dahlia coccinea shows a re- 
markable variation in color from cardinal 
of several shades through scarlet, scarlet- 
orange, mandarin, orange, lemon-yellow, 
yellow.; The so-called scarlet-orange rays 
are scarlet with lines of yellow running 
through, so that the strap-shaped corolla 
has a somewhat banded appearance. The 
ligulate corolla is about an inch long and 
half an inch broad. The entire head varies 
in size from two inches in the cardinal 
ones to three inches in the scarlet-orange 
ones. 
Dahlia Merckii runs from purple to pure 
white through the gradual fading-out of the 
*1891, Pringle, Garden and Forest, 1V., 40. 
} These colors have been compared with the colored 
silk samples issued by Belding & Co. and the Mary- 
land Silk Company, Hagerstown, Md. 
