158 The Irish Naturalist. October, 



occurrence in this count3^ Its increase since that date 

 must have been extremely rapid, and for fully forty years 

 prior to 1916 it was so abundant throughout this district 

 as to affect the coloration of every clover-field. It was 

 also common as a roadside plant, and in that capacity it 

 flourished chiefly as a parasite on White Clover {Trifolium 

 repens), though in meadow-ground it may have been — 

 as the editors of Cyhele Hihernica (1898) consider it to 

 be throughout Ireland — restricted to Trifolium pratense. 



As a roadside plant, however, Orobanche minor has now 

 vanished, and Trifolium repens has, therefore, possibly 

 ceased to be its host. And though in clover-fields it is 

 still far from extinct, the reduction it has undergone within 

 the past two years is certainly over 95 per cent. This is 

 not exclusively due to the severity of last winter, for I had 

 been struck by a marked decrease of this species in the 

 summer of 1916 ; but in 1917 the diminution has been still 

 more manifest, and it seems probable that the exceptional 

 weather has caused the further decline. 



The three other reduced species showed no symptoms 

 of any diminution until the summer of 1917. Not one of 

 them is now to be found in one-tenth of the quantity that 

 existed a year ago. 



Of these three species, two — the Weld and the Yellow 

 Fleabane — are known limestone-lovers. Reseda luteola is 

 referred by Mr. Colgan to his Calcicole B, and Pulicaria 

 dysenterica to his Calcicole C group. I do not know whether 

 Linum angustifolium is credited with any similar leanings 

 or not, but from the company it keeps I should not be 

 surprised to hear that it was so. We have no limestone 

 in this district, where the formation is of Silurian age ; 

 and it is possible that the few calcicoles we possess in our 

 decidedly calcifuge flora are for that reason peculiarly 

 sensitive to uncongenial weather, or any other change for 

 the worse in their surroundings. 



At any rate, it is a remarkable fact that even before 

 the destructive winter of 1916-17 we had lost or nearly 

 lost from this neighbourhood several of our more interesting 

 calcicoles — all within the past ten or twelve years — from 

 causes that I am quite unable to decipher. The most 



