

» 



i9i 7] COLE— POLLEN OF ROSA 113 



less than 10. In this group are R. rugosa, R. cinnamomea, R. Kelleri, 

 R. pendulina, and 7?. Moyesii. 



R. rugosa (figs. 5, 13) has almost no imperfect grains as may be 

 seen in the figures, practically all of the grains being perfectly 

 formed and full of protoplasmic contents. Fig. 5 shows the pollen 



y teazed out of the anthers on to a slide. Fig. 13 is a cross-section 



through an anther, showing the pollen grains in their normal posi- 

 tions in the loculus of the anther. It is worth while to note also the 

 generous quantity of pollen in the single loculus. Gray (F.F.G.) 



\ groups R. rugosa among the principal types of exotic garden roses 









mixed 



?? 



com 



instance, with R. rubiginosa (fig. 6) is its geographical seclusion 

 on the islands of Japan. The varieties of R. rugosa show evidence 

 of contamination, as will be shown later. 



R. cinnamomea and the 3 other species in this group (R. Keller i, 

 R. pendulina, and R. Moyesii) have not been figured. All may be 

 found in the Arnold Arboretum. They are all practically without 

 imperfect pollen grains, R. pendulina comes from the mountains 

 of Europe, and R. Moyesii comes from China. 



In the second and much larger group the percentage of imperfect 

 pollen is 10-50. In this group are R. spinosissima altaica, R. 

 spinosissima (garden variety hybrid), R. spinosissima, and R. 

 spinosissima hispida; also R. spinosissima paniculata (garden 

 variety). R. spinosissima fulgens (garden variety), because of 

 its larger percentage of undeveloped grains, belongs to the third 

 and last group. With these are R. Harrisoni (garden hybrid), i?. 

 gymnocarpa, R. Manetti (garden hybrid), R. blanda, R. seraphini, 

 R. ^ichuriana, R. no. 306 Wilson, R. pratincola, R. multijlora, R. 



( davurica, R. acicularis, R. hemispherica, and R. ferruginea. Of R. 



_ rugosa alba and R. virginiana alba, which properly belong in this 



group, I shall speak later in connection with other varieties of th< 

 same species in the third group. 



R. spinosissima and its 5 varieties present some very interesting 

 conditions. Fig. 12 is a cross-section of the typical anther of the 



, so-called species. It is very clearly seen that about 40 per cent of 



! the trains in the Iriniln* are shrivelled and without DrotonlasniiC 



* 



