THE BOOK OF ROSES. 19 



three generic species, viz., those of the Rosa 

 simplici folia, the Rosa lutea, and the Rosa 

 mutabilis. Varieties may be propagated by 

 any other mode of multiplication; but new 

 varieties can only be obtained from seed. 



Should any peculiarity appear in the flowers 

 of a branch of a specific rose-tree, the variety 

 may be instantly made permanent by a graft, 

 to be hereafter propagated by grafting, layers, 

 or slips. 



CHOICE OF SEED. The seeds should be se- 

 lected in autumn, as soon as they attain their 

 maturity, but left in the fruit till the moment 

 of sowing. 



To obtain double-flowers, preference should 

 be given to seeds gathered from double or 

 semi-double varieties, when they produce seed, 

 which is not always the case. The seed of 

 single flowers will never produce more than a 

 semi-double variety. 



Gardeners who wish to obtain hybrid vari- 

 eties, are careful, when the flowers are at the 

 height of their bloom, to cut off branches from 

 a flowering tree advantageous for the purpose, 

 and shake the pollen upon the stamens of a rose 

 of some other variety. 



Care should be taken to keep separate the 

 seeds of different species and varieties, as it is 

 desirable to ascertain positively from what fa- 

 milies arise the varieties produced. 



