1 9 1 7l COLE— POLLEN OF ROSA 1 1 5 



R. no. 306 Wilson, a Chinese wild rose, shows about 15 per cent 

 bad pollen; R. pratincola has about 25 per cent of its pollen grains 

 undeveloped; R. multiflora has about 20 per cent bad pollen. The 

 last is a rose native to Japan and China, and cultivated here. 

 Gray (F.F.G.) records it among the principal types of exotic 

 p garden roses: "R. multiflora Thunb. from Japan and China. 



Hardy in the Middle States, a double form of an old garden rose, 

 1 the single form not common. Polyantha roses are offshoots of 



this chiefly through hybridization with R. indica" 



R. davurica is a Siberian rose which shows more imperfection of 



pollen than R. spinosissima altaica, having 25-30 per cent of its 



pollen undeveloped, in contrast with 10 per cent in the other 



species. R. acicularis, another rose native to Siberia, is in a 



similar condition of probable contamination; this species is now 



wild in the Northern Hemisphere- R. hemispherica is a Persian 



yellow rose, probably like R. Harrisoni, an offspring of R. Eglanleria. 



I I examined the variety R. hemispherica plena, and found the pollen 



I in bad condition. The last of the species in the group is R. fer- 



** ruginea. native to the mountains of central Europe, and here also 



the pollen was to a large extent abortive, a condition interesting 

 when compared with that found in R. pendulina, likewise a native 

 of the European mountains, but almost without bad pollen. 



In the third group are those species with 50-100 per cent bad 

 pollen. This group is not quite as large as the second group, but 

 presents conditions even more interesting. It includes R. kam- 

 chatica, R. cordifolia, R. rugosa plena, R. rugosa alba, i?. rugosa 

 arnoldiana, R. oxyodon, i?. rubiginosa, R. setipoda, R. mollis, R. 

 macrophylla, R. canina biserrata, R. arvensis, R. gallica, R, alba, 

 R. damascena, R. virginiana plena, and R. Virginian a alba. 



Since the conditions as they appear in the species R. rugosa have 

 I already been shown, I shall first take up its 3 varieties. R. rugosa 



* 





plena has every appearance of a typical hybrid, as evidenced by a 

 large degree of sterility in its pollen (tig. 14). It seems clear that 

 about 90 per cent of the pollen is abnormal; and the contamination 

 is still more marked when we compare it with R. rugosa (fig. 13). 

 R. rugosa alba (fig. 15) is not in such bad condition as R. rugosa 

 plena, for in this case only about 40 per cent of the grains are 







