PARNASSIA PALUSTRIS VAB. CONDEN8ATA 85 



the latter rose is dominant over purple. In the former the 

 F x flowers are intermediate in size ; in the latter small flowers 

 are dominant. In both cases long runners are recessive. 



The varying degrees of sterility in these Epilobium hybrids 

 offer an interesting field for study, and cytological investigations 

 are already in progress. 



PAENASSIA PALUSTEIS var. CONDENSATA. 

 By J. A. Whbldon, F.L.S., and W. G. Travis. 



As our previous paper (Journ. Bot. 1912, 254), describing the 

 above-mentioned variety, has elicited some interesting comments 

 and criticisms, it seems desirable to supplement it by the following 

 notes, in which one or two points raised by correspondents can 

 be dealt with, and further information given as to the ecology of 

 the plant, its variability, and so forth. 



Several correspondents have pointed out the occurrence of 

 exceptions to the characters we attributed to the type and variety 

 when contrasting them. We should have stated in our original 

 description (loc. cit. p. 256) that the characters, proportions, &c, 

 there cited are average ones, such as are found in typical well- 

 grown examples. For instance, as regards the number of scapes, 

 we quote one to three for the type, and four to twenty for the 

 variety. We do not deny that the type has occasionally more 

 scapes, but this is exceptional. Young plants of the variety in 

 their early flowering period, or starved plants, may frequently be 

 found with a single scape. On the other hand, very luxuriant 

 examples have been seen bearing as many as forty scapes, but 

 these also are exceptional, and correspond to examples of the 

 type which bear a few more scapes than usual. 



The habitat of the plant in the Lancashire dunes is very 

 variable in character ; and in response to local modifications of 

 its environment the plant undoubtedly exhibits in certain respects 

 a not inconsiderable range of variation. But however extreme 

 these variations may be, they never obliterate, although they may 

 weaken, some of the characteristic features of the variety. In no 

 instance, however, have we seen the typical Parnassia palustris 

 of the upland moorland districts either amongst the dunes or in 

 their immediate vicinity. It may be of interest here to discuss 

 more fully some of the modifications to which the dune variety is 

 subject, and point out, as far as we can, their causes. 



The " slacks," or wet hollows among the dunes, in which 

 the plant grows, vary considerably in their edaphic and other 

 ecological conditions, the controlling factor being the amount of 

 moisture present. The most favourable situations for Parnassia 

 appear to be among the spongy moss-cushions and low herbage 

 in slacks w 7 here there is a liberal and fairly regular supply of 

 water, and where the soil, to a depth of several inches, consists 

 of sand with a large admixture of humus, due to the decay of 



