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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



serve that while the flowers of these plants differ from others in 

 the aggregation of many in one head, they are each in all essential 

 particulars the same as other flowers ; there is absolutely no 

 departure from the prevailing construction and the distinction of 

 the several parts. Thus in a Dahlia a number of flowers that 

 are called florets are associated in a cluster, forming what may 

 be termed a floral star. The several flowers in that star consist 

 of a calyx, a corolla of one petal, stamens, stigmas, and a one- 

 celled inferior ovary, containing one ovule. In examining a single 

 Dahlia we are immediately struck by the conspicuousness of the 

 external or ray florets, which encircle a closely packed central 

 disk, in which the stamens make themselves known by their 

 golden colour. If we pull a flower to pieces we discover that the 

 ray florets are tubular at the base only, where they present 

 occasionally aborted pistils, telling us that in acquiring a larger 

 size than the rest they have exhausted their powers, and are in- 

 capable of producing either stamens or stigmas. The outer 

 florets are in every sense sterile, and mere adornments, although 

 in that sense probably of vital importance, as attracting insects 

 to the flowers to effect fertilisation. The inner florets forming 

 the disk are minute, distinctly tubular, and in each is a closely 

 packed bundle of stamens that may be likened to the Eoman 

 fasces, from the summit of which protrudes the pistil, divided 

 into two or three stigmas. Each of these central fertile florets 

 terminates in an ovary, to which the calyx adheres so as to be 

 indistinguishable from it, and the result of fertilisation is a 

 cluster of dry seeds on the receptacle known to cultivators as a 

 "pod." The doiibling process consists in the multiplication of 

 ray florets and a corresponding suppression of disk florets ; or 

 we may popularly describe the process by saying that the short 

 corollas of the disk are converted into the prolonged corollas of 

 the ray, and correspondingly the organs of fertilisation are sup- 

 pressed also, so that in place of the productive flowers of the 

 disk we have the unproductive flowers of the ray, a conversion 

 of obscure fertile into conspicuous infertile flowers. 



The process of doubling consists, therefore, in the simultaneous 

 growth of ray florets at the expense of seed production ; the 

 flower becomes aristocratic, and ceases to be so productive as 

 when in its more humble form, and ends in becoming at once 

 splendid and sterile, in part or altogether. 



