98 / Knud Jessen. 



from the flower of another individual germinates or deve- 

 lops more quickly than does the pollen of the same flower. 

 But in case cross-pollination does not take place, self-pollina- 

 tion is inevitable ultimately when the short stamens dehisce." 



"I know no other Rubus-speciea in which self-pollination 

 is so well secured as in the present species, and this must 

 undoubtedly be regarded as an adaptation of the species to 

 the inclemency of the weather, to which it is probably often 

 exposed during its flowering period. The species which comes 

 nearest to it is, according to my observations, Riibus saxatilis, 

 which as is well-known extends even to the North Gape and 

 East Finmark and above the wood-limit in the mountains 

 of Norway and in the Alps." 



Poppius (1. c.) finds that the flowers are without scent 

 and secrete very little honey; he also records a proterandrous 

 stage before the homogamous. He writes that in foggy or 

 overcast weather the stamens bend inwards so that the an- 

 thers and filaments entirely cover the pistils. Numerous in- 

 sect-visitors are mentioned. Norman records that in the 

 districts of Arctic Norway where the plant sets fruit rarely 

 or only sparingly, the corolla is largest and most showy, 

 frequently with 6 — 8 petals which are 13 — 14 mm. long and 

 8 — 10 mm. broad, while in districts where the plant bears 

 fruit frequently the corolla is often much smaller, with petals 

 the length of which may be reduced to 9 mm. and breadth 

 to 5.5 mm. In Arctic Norway Rub. arcticus flowers in the end 

 of June and has ripe fruit in August (Norman). — Fruit- 

 dispersal probably by birds. 



According to the microscopical investigation of Riibiis 

 chamæmorus, Rab. saxatilis and Rub. arcticus mentioned above, 

 the first-named differs in several points from the other two, viz. 

 (1) in the structure of the absorbent roots, (2) in the structure 

 of the aerial shoot, (3) by the fact of its leaves bearing stalked 



