Composite Dahlia. 239 



has been observed in all the varieties raised. Perhaps chemistry 

 may some day tell us why. 



The culture of the Dahlia has probably been carried to 

 higher perfection in England than in any other country, for 

 almost without exception the varieties grown are of English 

 raising. Besides the old tall race, a new one of dwarfer stature 

 and another bearing smaller flowers have sprung into existence. 



The varieties of the different classes range from 1 to 6 feet 

 or more in height, and the flowers, or more properly flower- 

 heads, from 2 to 5 inches in diameter. The comparatively 

 recent Bouquet or Pompon Dahlias furnish the best varieties 

 for a small garden. In some of these the florets are beautifully 

 fringed, as in the pure white variety Guiding Star. For de- 

 tailed information respecting the numerous varieties we must 

 refer the reader to the catalogues of our great Dahlia growers. 



In addition to the above species there are two or three 

 others occasionally seen, including D. coccinea (fig. 127), a 

 rather taller plant with large scarlet sometimes semi-double 

 flowers ; and D. imperialis, of recent introduction, and better 

 adapted for a large conservatory than the open air. The latter 

 attains a height of 8 to 12 feet, bearing numerous smaller bell- 

 shaped heads of pure white flowers, with a crimson spot at the 

 base of each floret. 



TRIBE IV.SENECIONIDEJE. 



Leaves variable. Style cylindrical, with linear awns usually 

 fringed at the point, often truncate, or extended beyond the 

 fringe in a cone or other appendage. 



14. SlLPHIUM. 



A small genus of herbaceous plants of rather large stature, 

 having opposite whorled or alternate leaves and large yellow 

 monoecious flower-heads. Kay-florets female, and disk-florets 

 barren. Achenes large, flat, winged longitudinally, the latter 

 sometimes toothed at the top, and representing the pappus. 

 Natives of North America. 



1. S. laciniatum (fig. 128). Compass Plant or Rosin-Weed. 

 The slender stems of this species rise to a height of 3 to 6 

 feet, surmounted by large flower-heads, yellow with a dark 

 centre. It received the name of Compass Plant because it was 

 supposed that the leaves invariably presented their surfaces 

 due north and south ; arid the second trivial name was given 



