114 BOTANICAL GAZETTE [February 



contents; and the contrast between these and the perfect grains 

 is very marked. 



In comparing the species R. spinosissima with the recog- 

 nized garden hybrid, a variety of the species and called R. spinosis- 

 sima garden variety hybrid (fig. 10), the latter shows less pollen 

 in the loculus, but about the same percentage of shrivelled grains. 

 R. spinosissima paniculata, another garden variety, has only about 

 10 per cent of its pollen grains undeveloped; while still a third 

 garden variety, R. spinosissima Jul gens , has a larger percentage than 

 any of the group I have examined. This last, as may be seen in 

 fig. ii, has an abundance of pollen grains in the loculus, but about 

 50 per cent of them appear as tiny, shrivelled cells. 



The two remaining varieties of R. spinosissima, R. spinosissima 

 altaica and R. spinosissima hispida, are apparently the least con- 



* 



taminated of the varieties. The first, a Siberian rose (fig. 8), has a 

 considerable amount of pollen in the loculus, and only about 10 

 per cent of its grains are bad. The second (fig. 9) presents an 

 almost identical situation; and this is a European variety of the 



same 



Harrisoni 



hybrid . 



typ 



being im 



entirely shrivelled. Gray (F.F.G.) described "R. Eglanteria L. 

 a yellow Eglantine rose. Like a sweetbriar, but lower. Austrian 

 briar, Persian vellow, and Harrison's vellow are forms of this." 



specimens 



exam 



hybridism 



developed pollen usually accepted as indicatin 



Manetti, another garden hybrid (fig. 17), presents a condition 

 ;ous to that found in R. Harrisoni. R. gymnocarpa, a north- 

 n North American rose, is much less contaminated than the 

 ro, only about 20 per cent of its pollen grains being imperfect. 

 e remaining species of the group under discussion present 

 ions more or less similar to those already described. R. 



phini has 



numerous 



