GENEKA AND SPECIES. 49 



species, into cold ones, like beams of light stretching faintly into 

 distant darkness, as if they would invite us to visit the realms of their 

 magnificence. 



GENERA AND SPECIES. 



" Genera " bear the same relation to families that the families do 

 to the great primary classes. Walk round a large garden, and you 

 will see many kinds of lupine, and many kinds of larkspur. Each of 

 these little companies is a " genus," and each of its constituent kinds 

 is a "species." The "genera" are distinguished by peculiarities in 

 the flower and fruit, while the " species" depend on differences in the 

 form of the leaves and inflorescence, and in the general habit and 

 configuration of the plant. In some families the genera are exceed- 

 ingly difficult of discrimination. They are almost always a source of 

 perplexity, since we have usually to wait for the ripe fruit before we can 

 determine them, by which time the flowers are gone, and the foliage 

 is often faded . Endeavour is made, in the present volume, to obviate 

 this hindering difficulty, by means of a key to the families and 

 species, independent of the generic characters, leaving the latter to be 

 studied subsequently from other works. The name Avill always shew 

 what genus a plant belongs to, and all that is practically wanted to 

 ascertain it appears either as family character or specific character. 

 When once a species is well known, all the others of the genus includ- 

 ing it are for the most part easily identified as such, even when seen 

 for the first time, by the similarity of their habit and contour. The 

 external likeness is almost always a readier guide than the strict 

 technical or scientific character. 



Species are generally plain enough ; every one knows a moss-rose 

 from a monthly-rose, and both from the common dog-rose of the 

 hedges, the single genus "Rose" including all three, along with many 

 more. Most, however, of the fancy roses grown on lawns and in par- 

 terres are only " varieties," that is to say, casual deviations from the 

 wild specific type, induced by cultivation, and by accidents of soil and 

 situation. Dahlias, in like manner, are only " varieties ; " and the 

 same is the case with pansies, hyacinths, and the majority of "florist's 

 flowers." Brambles and ferns exhibit a similar aptitude to sport into 

 "varieties," even while growing in their native habitats. The difier- 

 ence between a mere "variety" and the original form is that the 

 former can rarely be depended on as permanent when the circum- 

 stances that originated it cease to operate, and that it seldom repeats 



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