THE HORTICULTURAL SOCIETY OF NEW YORK 



variabilis, for variable it certainly was. Though the flowers of 

 the first-known forms were single or semi-double, some of their 

 progeny soon began to throw double flowers, and these double- 

 flowered forms became increasingly popular. By 1826 there 

 were sixty varieties under cultivation by the Royal Horticultural 

 Society of England, and by 1841 one .English dealer is said to 

 have listed 1,200 varieties, all supposed to have descended from 

 the Mexican stock, mostly single-flowered, that had entered 

 Europe by way of Madrid. 



In America, the general catalogue of George C. Thorburn, pub- 

 lished in New York in 1838, offered a choice selection of twenty- 

 five double dahlias for $20 and stated that a special " catalogue 

 of double dahlias is published annually, in March, including all 

 the newest and finest in England." Furthermore, in this Thor- 

 burn catalogue of 1838, we find that "In the dahlia season (last 

 week of September), ladies and admirers of that favourite flower 

 are invited to witness the annual show, which this season will be 

 surpassingly varied and splendid." 



Relationships 



The dahlia belongs to the family Compositae (or Carduaceae, 

 as the family is now sometimes known) and is a close relative 

 of our native species of Coreopsis and Bidcns ("beggar-ticks") 

 and our cultivated Cosmos. What we commonly call the flower 

 is l)otanically, as also in the sunflower, a flower-cluster or head, 

 made uj) of numerous closely aggregated flowers, which are often 

 of two or more kinds. In the so-called single dahlias, a few 

 outer flowers of the cluster have broad flat conspicuous expanded 

 corollas, the rays (popularly but not botanically the "petals"), 

 while the inner or disc flowers, including most of the flowers of 

 the cluster, have small inconspicuous, tubular corollas. 



Classes 



Growers and exhibitors of dahlias recognize several different 

 classes or groups of dahlias, based upon the form and other 

 characters of the "flower" or head. The extremes of form are 

 very pronounced and it is usually easy to say into what class a 

 flower is to be placed ; but here, as elsewhere in nature, and more 



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