EXHTTUTION MEETING, 1 O'O 
r,R 
at the Westmorland sites and possibly in other areas, for it appears 
that its occurrence in close proximity to the rock surface is indicative 
of survival tit- situ. It may have been more widely distributed, and if 
this be so, then leaching and the spreading of the dominant tree 
species in the Post-Glacial Period were probably the cause of the re- 
striction to the sites that it occupies to-day. 
Miss M. E. Griffiths. 
Srn-sPEriPic Variation in LATHY BUS NISSOLIA 
The exhibit demonstrated the results of recent experimental and 
other critical work on the sub-specific taxonomy of L. nis.'^nJia L. 
Two varieties were recognised, the delimitations of which were de- 
rived, after considerable amendments, from very inadequate and ])ar- 
tially erroneous descriptions by early continental authors. 
It was shown that by the use of several biometrically assessed 
“micro” charactei’s, two clearly defined varieties could be recognised. 
These preliminary conclusions were confirmed by the demonstration 
of correlated ecological attributes for each variety. 
The continental authors were in error when they nominated var. 
puhescPus of G. Beck as the type variety. The Linnean type in fact falls 
within var. (jlahreseens Freyn., the other van’ety recognised on the con- 
tinent. 
All the British material examined, with the exception of one speci- 
men, was leferable to the type variety (var. ni.s.so7/u) ; it is likely that 
this odd specimen was of adventive origin. 
A fuller account will be published in due course. 
Miss ]\r. J. Heuhkrt A J. F. M. Cannon. 
Variation in NYMPH.AE.^ in the British T.sges 
The common white water lily (V. alha L.) shows great variation in 
size of organs and numbers of floral parts, and in attempts to give 
taxonomic recognition to this variability various taxa, e.g. N. 
occidentalis (Ostenf.) Moss, have been erected. During the last three, 
flowering seasons the structure of populations of N. alha in various 
parts of the British Isles has been studied by mass sampling technique, 
and the exhibit showed parts of population samples from English, 
Scottish and Irish localities and some of the biometrical data derived 
from them. The general conclusions reached in the study so far are 
(1) that colonies differ greatly in their amount of genetical variability 
and in their average composition; (2) that part of the variability in size 
and number of parts can be correlated with habitat conditions, the 
colonies containing larger plants often tending to occur in the richer 
habitats ; (3) that much of the variability is random, showing no 
significant geographical or ecological regularities, and (4) that “ N. 
occidentalis ” and other taxa based mainly upon sizes and numbers 
of parts are of little value, since they refer to plants at the tail of 
the variation range of N. alba which may be found in almost any 
large colony. 
