12 



Miss E. R. Saunders. On a Discontinuous 



tain the facts of inheritance, as regards this particular character, 

 that the following observations were undertaken. 



Biscutella Icevigata has a perennial rootstock bearing a crown of 

 radical leaves. 



The leaves are obovate, oblanceolate, or spatalate, tapering down- 

 wards to the petiole ; the apex is obtuse, and the margin either entire 

 or dentate-sinuate, with a water gland at each marginal tooth or 

 lobe. The cotyledons are obovate, they scarcely taper, and the 

 margins are invariably entire. In those plants in which the more 

 elaborate type of leaf occurs, the first post-embryonic leaves are 

 transitional between this and the simple entire form of the cotyledons. 



In respect of flexibility, the leaves of different individuals show 

 very considerable variations. In some plants (and this is more par- 

 ticularly the case with those which are glabrous) they are stiff and 

 brittle and readily crack if the lamina is bent upon itself ; in others 

 this bending produces no lesion. 



Far more striking, however, are the variations in the character of 

 the leaf surface, which, as stated above, include intermediate grada- 

 tions between leaves in which both the superficies and the margin 

 are thickly covered throughout their whole extent w r ith rather stiff 

 hairs, and leaves in which the lamina is completely glabrous. 



Upon referring to the descriptions of previous observers, I found 

 that several agree in recording the variable character of the leaf 

 surface ; as regards the predominance of the different forms, their 

 statements are, however, not altogether in accord. 



Rouy and Foucaud* describe the leaves of Biscutella Icevigata as 

 rough and hirsute, rarely glabrous and smooth. 



Parlatore,f in his simple unqualified statement that the leaves are 

 glabrous or hispid, gives no hint that he regards the latter as the 

 predominant and typical form ; in a concluding note he adds that 

 . the variations in the degree of hairiness, as of other characters, form 

 such a continuous series, that to consider them of taxonomic value in 

 distinguishing varieties (unless almost infinite in number) would be 

 entirely arbitrary. 



Christ,* in contrasting the variety saxatilis with the type form 

 {i.e., Icevigata), in like manner describes the latter as glabrous or 

 pubescent. 



Mertens and Koch§ deal with these variations in greater detail ; 

 according to them the leaves may be either thickly covered on both 

 surfaces with rather stiff, spreading hairs, or they may be rough in 



* ' Flore de France,' t. 2, p. 104. 



f 1 Flora Italiana,' vol. 9, p. 651. 



X ' La Flore de la Suisse,' p. 121. 



§ ' Deutschland's Flora,' vol. 4, p. 504. 



