218 BRITISH PLANTS 



birthwort, rupture- wort, fleabane, gout- weed, lousewort, 

 scabious, scurvy-grass, spurge, whitlow-grass. 



This nomenclature was clumsy and unsatisfactory. 

 Many plants remained nameless. The names applied to 

 others were vague, referable to one plant in one district, 

 and to another in another e.g., the sea-purslane is either 

 Arenaria peploides or Atriplex portulacoides . The same 

 plant, too, had many aliases. In other cases a common 

 name covered a multitude of species e.g., buttercup, 

 stonecrop, tare, vetch, violet. For scientific purposes 

 this nomenclature was impossible. Besides, science is 

 cosmopolitan ; it recognizes no race and no boundaries. 

 What was wanted was a definite name for every plant, 

 and one which botanists of all countries could use and 

 understand. 



Many attempts were made to remedy this state of 

 things, but the honour of founding a system of nomen- 

 clature which was destined to be universally adopted 

 belongs to Linna3us, a Swedish botanist, the bicentenary 

 of whose birth was celebrated all over Europe in 1907. 

 He gave each plant two names, each thrown into a Latin 

 form. The first was the name of the genus, the second 

 that of the species. For example, there are many kinds of 

 buttercups, all of which bear a strong family likeness to 

 one another, especially in the flowers. Linnaeus gave the 

 generic name Ranunculus to the family group, and his 

 description of the genus was an enumeration of those 

 characters in which the various buttercups agree with 

 one another. The genus as a plant does not exist ; only 

 species exist. The genus is an abstraction, invented for 

 the convenient purpose of denoting a group of species 

 which possess many characters in common. Each species 

 agrees with the characters ascribed to the genus, but 

 differs from every other species by one or more characters, 

 which never vary. 



The classification of plants is based upon similarities 

 and dissimilarities, but it is a matter of choice what par- 

 ticular characters we select for comparison. Similarity 

 very often implies relationship, and this is especially true 

 in the case of the flower the most conservative part of 

 the plant, and the part least affected by external condi- 

 tions. In a natural system of classification it is necessary 

 to select those characters for comparison which denote 



