December 1 901 . 233 



NOTES ON IRISH TOPOGRAPHICAL BOTANY, 



WITH SOME REMARKS ON FLORAL DIVERSITY. 

 BY NATHANIEL COLGAN, M.R.I. A. 



IT is hardly possible within the limits of the few pages to 

 which ordinary reviews are restricted to do full justice to a 

 work of such magnitude as Mr. Praeger's Irish Topographical 

 Botany. Some of the features of the book have consequently 

 received but scant discussion in the reviews hitherto 

 published, so that the following supplementary notes sug- 

 gested by a leisurely study of the volume may, it is hoped, be 

 found helpful towards a better appreciation of its merits. 



In the first place, Mr. Praeger's treatment of that attractive 

 but difficult subject, the soil relations of plants, deserves 

 special commendation. Man has been defined as a general- 

 ising animal ; and there are few fields of inquiry in which the 

 free indulgence of the bent towards generalisation is more 

 likely to lead him rapidly and profoundly astray than this of 

 the soil affinities of plants. Here, in an eminent degree, a 

 little knowledge is a dangerous thing. The inductions which 

 appear amply justified by the study of a parish flora may be 

 completely upset by the botanical survey of a county or even 

 of a barony. And, indeed, a very wide knowledge of plant 

 distribution — an intimate acquaintance with the flora of a 

 whole Irish province — is not enough to guard the investigator 

 against serious error. Your table of calcicole and calcifuge 

 plants, based perhaps on the labour of years in the Leinster 

 counties, may suffer some rude shocks when confronted with 

 the flora of the " crags " in Burren or in East Galway ; and 

 as your field of view widens you will come to regard many of 

 the cherished inductions of your earlier stage as the dog- 

 matisms of half-knowledge. Ever}- reader of Mr. Praeger's 

 work must recognise how close a study he has made of this 

 difficult subject, and how completely the wide range of his 

 observations and his appreciation of the complexity of the 

 factors which operate in plant distribution, have enabled him 

 to avoid anything approaching to crude generalisation. The 

 section of his Introduction which deals with " Plant Groups 

 dependent on Soil or Moisture " and the many remarks on 



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