1903-1904.] 219 



they could easily distinguish between those plants which had 

 to guard against drought — xerophytes, as they were termed — 

 from those whose habits of life were such that water was 

 usually in excess — -termed hydrophytes. The vegetation of 

 sandy shores, of rocks, and desert places was essentially xero- 

 phile in character, while that of marshes and pools was hydro- 

 phile. Between these extremes lay the vegetation of our 

 meadows, woods, and cultivated land, where the water supply 

 neither greatly exceeded nor fell below the requirements of 

 the plants ; the plants composing such associations were termed 

 mesophytes. The special adaptation of xerophytes consisted 

 mainly of devices for obtaining the necessary supply of water, 

 and for storing it and preventing its loss. Such plants had 

 usually a well-developed root-system, and showed a reduction 

 of their vegetative parts; the leaves, for instance, were small, 

 sometimes rolled in, sometimes altogether wanting. A thick 

 impervious skin was also very characteristic, or a coating of 

 felty hairs. In hydrophytes, on the contrary, they found a 

 very thin skin and a reduced root-system. Mr. Praeger then 

 briefly sketched some of the most characteristic plant associa- 

 tions of our own country, such as that of the sea-rocks, sand- 

 dunes, salt-marshes, bogs, meadows, and woods, pointing out 

 the leading conditions under which each plant-group lives, 

 and its special adaptations to its environment. From that 

 he passed to the geographical study of vegetations and the 

 mapping of leading associations. The history of this 

 branch of botany was briefly sketched, with a special 

 reference to the work done in recent years in Scotland 

 and in Yorkshire ; and then an account was given of the 

 mapping of the plant associations of the Dublin mountains, 

 on which Dr. Pethybridge and he had been for some time 

 engaged. Sheets of the Dublin plant survey and photographs 

 of the associations were shown and methods described. In 

 conclusion, the speaker strongly urged the claim of this branch 

 of botany, hitherto untouched in the North of Ireland, on the 

 members of the Club. 



The Chairman referred to the work done by W. G. 

 Smith, and said he had copies of that gentleman's papers 



