THF, OKNUS ROSA 293 



Two or three specimens, of which the inset on the left of 

 Plate XV. B represents a leaf, are so abnormally microphyllous 

 as to suggest as their possible origin a back cross between 

 such a plant as I figure and Rosa pimpinellifolia. 



(7) R. pimpinellifolia X R. omissa. Plate X. 



Again I have had to rely on Mr. Barclay for the specimen 

 placed before us in this plate. It was collected from his fertile 

 Auchterarder bush ; from its fruit, foliage, and glandular 

 development, assisted by a reference to the bushes growing 

 with it, Barclay satisfied himself that its parentage was that 

 just stated. Its exaggeration of the prickle armature on fruit 

 and peduncles is very noteworthy, and is typical of many 

 pimpinellifolia hybrids. Since, in many instances, this 

 surpasses in strength that of its parents, it caused much 

 tribulation in the minds of early workers. No doubt the 

 phenomenon is to be attributed to the action of heterosis. 



(8) R. pimpinellifolia X R. omissa. Plate XIII. 



Once more Northumberland provided the specimen 

 illustrated. This was gathered near Slaley on the same day 

 as the pimpinellifolia X fnollis described previously. On that 

 date, July i6th, 1919, the fruit shown was about the best left 

 on the bush. Under the plant, on the clayey bankside, 

 thousands of immature fruits lay rotting, and others were 

 ready to follow them. 



Relying on book descriptions, this plant would appear to be 

 R. Sabini, and has been so called by such a competent 

 observer as Baker. Comparison with Plate X. will reveal 

 what a heterogeneous mass comes under that name. My 

 determination of its origin depends on critical examination of 

 the plant and its neighbours. 



Baker and Tate refer in their "New Flora," 1868, to the 

 very bush, and localise it so exactly that no mistake is 

 possible; this means that this plant has persisted in its 

 original station for 60 years at least. 



H 



