Ixxii IlSrTEODUCTION. 



localities are given only for the districts in -wliicli it is rare. The 

 inclusion ia brackets of a district number at the head of a para- 

 graph indicates that the plant is doubtfully established, or perhaps 

 extinct iu that district. The district distribution as shown at the 

 head of each paragraph includes that of all the Irish varieties as 

 ■well as of the type. 



Native and Non-native Plants. — In the text the numerous plants 

 known or suspected to have been introduced by human agency, 

 whether accidental or intentional, are distiuguished from the 

 apparently native plants by the usual signs, f, %, or *- The first of 

 these denotes that the plant to whose name it is affixed is open to 

 a slight suspicion of having been introduced by the agency of man, 

 the second that it was probably, and the third that it was certainly 

 so introduced. Perhaps not one of the non-native plants known ta 

 occur in several of the Irish botanical districts stands on precisely 

 the same footing in each. While apparently all but native in one 

 district, a plant may be obviously introduced in another ; and since 

 it is beyond the scope of this work to exhibit the standing of each 

 non-native species in the various districts in which it may occur, the 

 sign selected in the text is that which denotes for each of such 

 species its highest standing in any part of Ireland — that is to say, 

 its standing most closely approaching to true nativity. 



Range in Latitude. — In tracing the range in latitude of Irish 

 plants, the island has been assumed to lie between the parallels of 

 51^° and 55 J° North latitude, the extent of land lying north and 

 south of these limits being inconsiderable. Within these limits 

 the range of each species has been ascertained to the nearest 

 quarter degree. With some of the rarer or more local plants the 

 range has been given with greater precision. It has not, how- 

 ever, been thought necessary to give the range in longitude for 

 each species. Those which have a distinctively eastern and 

 western distribution will be found set out in the section (VII.) 

 of this Introduction dealing with Topogi-aphical Groups. 



Botanical Types. — For the purpose of comparison with the 

 British Plora, Watson's botanical type-names have been given for 

 each species save those peculiar in the British Isles to Ireland. 

 These have been classed under the name Hibernian type. To the 

 explaaiation of Watson's types already given in a previous pai-agraph 

 of the Introduction, it may be added here that the union of two 

 type-names, as in the compounds, British-English and English- 

 Germanic, indicates that the plant so classed, while belonging to the 



