CHAP. HI.] ROSE^. 53 



are a long time before they come up. Fig. 22 

 is the ripe fruit of Rosa cumamonea, cut in two to 

 show the nuts. The leaves are 

 pinnate, consisting of two or 

 more pairs of leaflets, and ending 

 with an odd one. The leaves 

 are furnished with very large 

 stipules (see Jig. 20 e) ; and the 

 stems have numerous prickles fjg. 22.— ripe fruit 

 (/), which differ from thorns in and detached seed 

 being articulated, that is, they 

 may be taken off without tearing the bark of 

 the stem on which they grow, only leaving the 

 scar or mark, shown at g. The leaves of the 

 sweet briar are full of small glands or cells 

 filled with fragrant oil, w^hich may be distinctly 

 seen in the shape of little white dots, when 

 held up to the light ; and this is the reason of 

 their delightful perfume. When the leaf is 

 rubbed between the fingers, the thin skin that 

 covers the cells is broken, and the oil being 

 permitted to escape, the fragrance is increased. 

 There are only two genera in this tribe, viz. 

 Rosa and Loicca^ the latter containing only 

 what was formerly called Rosa herherifolia^ and 

 which has been thought worthy of being made 

 into a separate genus principally on account of 

 its having simple leaves without stipules, and 

 branched prickles. 



