8 



YOLANDE HESLOP-HARRISON 



between N. lutea and N. pumila, and it has since been customary to assume that N. inter- 

 media does not in fact represent a pure breeding species but simply an assemblage of 

 natural hybrids. Particular interest attaches to this ascription of a hybrid origin to 

 N. intermedia because, in many localities from which this taxon has been reported, one 

 or other, and sometimes both, of the presumed parents are missing. That this is so for 

 certain British stations of N. intermedia is apparent from Fig. 1, which shows the Scottish 

 and northern English ranges of the two parents and the presumed hybrid. The distribution 

 of N. lutea is shown by vice-counties, those of N. pumila and N. intermedia by spot 

 marking, the localities indicated being those from which specimens exist in the herbaria 

 of the British Museum (Natural History), the Royal Botanic Gardens of Kew and Edin- 

 burgh, and Cambridge University. N. lutea is, of course, mainly a lowland plant of 

 lakes, slow rivers and canals, while N. pumila today is, for the most part, confined to 

 high-level lakes in mountainous regions, an exception being the remarkable colony which 

 exists in one of the Shropshire meres, a locality first reported by Cox (1855). While 

 many of the colonies of N. intermedia occur within the area of overlap of the two presumed 

 parents, one, in Ardnamurchan, is in a vice-county (v.c. 97, Westerness) from which 

 neither has been recorded; and others, in southern Scotland and in Northumberland, 

 are remote from areas where N. pumila is known today. 



If N. intermedia is indeed a hybrid, this persistence outside of the range of its presumed 

 parents is of considerable historic as well as taxonomic interest. The present paper 

 contains a review of the evidence for accepting it as such, as well as some speculation 

 relating to its possible origin in the British stations. Particular attention is paid to the 

 colony in Chartners Lough, Northumberland, where N. intermedia exists in a station 

 very distant from the nearest " pure " N. pumila. The important work of Caspary in 

 connection with the problem of N. intermedia in Continental Europe is also reviewed. 



N. intermedia in Chartners Lough, Northumberland 



This station for N. intermedia was first discovered by Sir John Trevelyan, and placed 

 on record by Winch (1832), in his remarkable flora of Northumberland and Durham, as 

 N. lutea var. /3 pumila. From this date Chartners became a classical locality for the 

 plant, featuring in practically all local and national floras in which the genus was treated 

 in any detail. The taxonomic treatments given it differed according to the nomenclature 

 currently in favour : 



N. J. Winch (1832),* " N. lutea var. /S pumila " (collector Sir J. Trevelyan). 



H. C. Watson (1835), " N. pumila " (collector Sir W. C. Trevelyan). 



W. J. Hooker (1835), " N. pumila (= N. kalmiana) " (collector Sir J. Trevelyan). 



H. C. Watson (1847), " N. pumila De C." (collector Sir W. C. Trevelyan) 



W. J. Hooker & G. A. W. Arnott (1855), " N. pumila De C." 



J. T. Syme (1863), " N. lutea Sm. var. ^ minor." 



J. G. Baker & G. R. Tate (1868), " N. intermedium Ledeb." 



J. D. Hooker (1884), " N. luteum Sm. var. N. intermedium Ledeb." 



W. R. Hayward (1892), " N. luteum ^ N. intermedia Ledeb." 



J. L. Luckley (1893), " N. lutea var. /8." 



C. E. Moss (1920), " N. pumila var. intermedia Moss." 



Winch himself (1832) reported the results of what must be one of the earliest examples 

 of British experimental taxonomy - a transplant experiment on the Chartners plant - in 

 the following words : " Some years since, the least yellow water lily was transplanted 

 from the subalpinc moors into the ponds at Wallington, where it now scarcely differs 



• Referred to as N. minma in a letter dated J6.4 J4 from Wineh to J. E. Sniith (Smith 1S32). 



