1916-17.] BOTANICAL SOCIETY OF EDINBURGH 161 



scurfy indumentum layer the floccose hairs on the under 

 surface of the leaf ; Rh. araio'phylluin has often shreds or 

 patches of indumentum adhering to the veins on the under 

 leaf-surface, as has also sometimes Rh. anthosphaerttm ; Rh. 

 hylothreptuin has often glands on the lower midrib which 

 may be also slightly puberulous. The places where vestiges 

 (apart from the punctulae) remain most constantly are the 

 groove of the upper midrib and of the petiole and the 

 petiole itself. Rh. irrorahim is one of the species which 

 seems to get rid of most of its early indumentum ; yet in 

 plants from the Chungtien plateau quite a stratum of grey 

 withered indumentum may remain on stem and petiole. 

 In Rh. pogonostylum this stratum in the few specimens 

 we have remains for a couple of years. There is room 

 here for considerable yariation in individual plants, and from 

 what I have said the point of my comment that glabrescent, 

 not glabrous, is the more correct descriptive term to use 

 in speaking of the mature state in these species will be 

 apparent. I must add this. In some species the vestigial 

 cones of the fallen glands or hairs are hard to find even 

 under some considerable magnification on the upper leaf- 

 surface. One can hardly speak of the surface as punctu- 

 late. Apparently the vestigial cones are very low and do 

 not colour red or orange, and are thus inconspicuous. I 

 have not sifted this matter. Then the vestigial cones on 

 the leaf margins are more feebly developed in some species 

 than in others. Rh. irroratwm oflfers an example of con- 

 spicuous development, so much so that the projection of 

 these cones associated with the slight undulation gives an 

 appearance of notching to the leaf margin which is very 

 characteristic. Where the vestiges are smaller the effect 

 they give is that of a roughening of the edge. This 

 juvenile indument character and its graded removal is 

 most typical of the Irroratum series. Although I have 

 been able to trace the development in only four out of 

 the thirteen species, yet the similarity in mature characters 

 of all of them seems to demand the same explanation, and 

 I feel justified in assuming that when the material required 

 for investigation is obtained it will support my prediction 

 of like development. 



Two modifications have to be recorded. 



