68 THE BOOK OF ROSES. 



ters only such as are invariable, and having 

 minutely examined the organic distinctions 

 between all the species of roses now in cultiva- 

 tion, we decide that only two characters are 

 invariable, a pure yellow colour, as opposed to 

 white or red ; and single leaves, as opposed to 

 composite. On these grounds, we propose as 

 species exhibiting invariable characters : 



I. The Rosa simplicifolia, or berberifolia, 

 having flowers of a pure yellow, thorns (in its 

 natural state) composite, and single leaves. 



II. The Rosa lutea, flowers of a pure yel- 

 low, single thorns, composite leaves. 



III. The Rosa mutabilis, pink flowers vary- 

 ing in every shade from white to crimson, 

 thorns single, leaves composite. 



All the roses in existence we consider but as 

 families or varieties derived from these funda- 

 mental types, the mere result of accident or 

 difference of culture or climate. The roses of 

 Asia, for instance, resemble each other; the 

 roses of America resemble each other ; the roses 

 of Europe resemble each other ; while we find 

 the greatest difference of aspect between the 

 roses of Asia and the roses of America, and the 

 characters of each may be changed by trans- 

 plantation to a different climate and mode of 

 cultivation. But no change of climate or culti- 



