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On Thlaspi perfoliatvm, L. By W. T. Thiselton DrEu, B.A., 

 B.Sc. 



It has been pointed out by Mr. Watson* that the most local 

 species of British flowering plants belong to two classes as 

 regards their distribution, namely, those which are found only 

 in the south of England, and secondly the assemblage of Alpine 

 and Arctic plants peculiar, as far as Britain is concerned, to 

 the Eastern Highlands of Scotland. Thlaspi perfoliatum, L., 

 is an example of the first class, as in Britain it has only 

 hitherto been gathered on the Oolites of Gloucestershire and 

 Oxfordshire. Mr. Watson, in his latest pubhcation on the 

 distribution of British plants, places Oxfordshii-e within brackets, 

 by which it is intended to show that probably the Thlaspi is no 

 longer to be found in that county, so that Gloucestershire now 

 stands alone as a locality for it. 



In Dr. Hooeek's Student's Flora, p. 38, Tlilaspi perfoliatum 

 is said to affect 'limestone pastures.' I beheve, however, that 

 when growing it wiU. generally be found to prefer weathered 

 limestone rubbish. As it is an annual of small dimensions and 

 very short duration, it would be quite an exceptional thing for 

 a plant so constituted to be able to hold its own against the 

 perennial vegetation of pastures. 



In Oxfordshire it was originally found "among the stone pits" 

 (quarries) between Witney and Burford, (Eay's Synopsis, Ed. 

 iii., p. 305), and more recently, a specimen in the British 

 Museum was collected by Mr. Bicheno, 4i miles from Witney, 

 on the Burford Eoad. Some years ago my fi-iend, Mr. Boswell, 



* Cybele Britannica, vol. iv., p. 445. 

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