INTRODUCTION XXXlll 



PART II 



THE CLASSIFICATION OF PLANTS 



So great is the number of different kinds, or species, of plants 

 that no one could possibly bear them all in mind or recollect their 

 distinctive characteristics. Whilst in 1753, when the great 

 Swedish botanist Linnaeus published his " Species Plantarum," 

 only 7,300 species were known to him, botanists at the present 

 day have upwards of 100,000 species to deal with, of Flowering 

 Plants alone. It becomes necessary, therefore, to classify them in 

 a succession of larger or more general groups, accordmg as they 

 agree with one another in many or in fewer characters. We can 

 then more readily remember the characters of the comparatively 

 few larger groups ; and, knowing them, can on examination refer 

 any plant to its position in the classification. 



Plants which agree in all essential points, though differing 

 perhaps in size or in the colour of their flowers, are said to belong 

 to a single species. Naturalists of all schools of thought agree 

 that the individuals of a species have all had a common ancestry. 

 Each species has a Latin or scientific name, which since the time 

 of Linnaeus ^ has consisted of two words, the second of which is 

 peculiar to it and is known as the specific name, whilst the first is 

 known as the generic name, being shared with other species, 

 which, agreeing in certain characters, are said to belong to the 

 same^d';^//i-. The wild Sweet-scented Violet, for example, is called 

 by botanists Viola odordta, the name Vioia indicating that it 

 belongs to the genus so called. Besides the Scented Violet, we 

 have wild in England the Marsh Violet, the Hairy Violet, the 

 Wood Violets, the Dog Violet, the Pansy, and several others, all 

 belonging to the same genus, and, therefore, described under the 

 name Viola. But the Marsh Violet differs from the Sweet- 

 scented in having broader and blunter leaves, in being almost 

 entirely free from hairs, and in having smaller, pale lilac, scentless 

 flowers, with a shorter spur to the corolla, besides growing in much 

 wetter situations. The Marsh Violet is, therefore, a distinct 

 species, Viola palilstris. 



It is by no means easy to determine what characters are 

 sufficiently constant, true to seed, and important to constitute a 

 species. Among the Wood Violets, for instance, we may find 



1 No little merit is due to Linnaeus for inventing the specific name of plants. The method 

 in use previously was to attach to every plant some such title as the following : — Gravten 

 xera»ipelinu7n, miliacea, pertenui 7'ainosaque sparsa panicula. The name of this grass 

 Linnaeus expressed with precision and simplicity by the two words, Poa bulbosa. 

 C 2 



