OUTLINES OF BOTANY. 



CHAP. II. CLASSIFICATION, OB SYSTEMATIC BOTANY. 



176. It has already been observed (3) that descriptions of plants shonld, 

 as nearly as possible, be arranged under natural divisions, so as to facilitate 

 the comparison of each plant with those most nearly allied to it. The de- 

 scriptions of plants here alluded to are descriptions of species ; the natural 

 divisions of the Flora refer to natural groups of species. 



177. A Species comprises all the individual plants which resemble each 

 other sufficiently to make us conclude that they are all, or may have been 

 all, descended from a common parent. These individuals may often differ 

 from each other in many striking particulars, such as the colour of the 

 flower, size of the leaf, etc., but these particulars are such as experience 

 teaches us are liable to vary in the seedlings raised from one individual. 



178. When a large number of the individuals of a species differ from 

 the others in any striking particular they constitute a Variety. If the 

 variety generally comes true from seed, it is often called a Race. 



1 79. A Variety can only be propagated with certainty by grafts, cut- 

 tings, bulbs, tubers, or any other method which produces a new plant by 

 the development of one or more buds taken from the old one. A Race 

 may with care be propagated by seed, although seedlings will always be 

 liable, under certain circumstances, to lose those particulars which dis- 

 tinguish it from the rest of the species. A real Species will always come 

 true from seed. 



180. The known species of plants (now near 100,000) are far too nu- 

 merous for the human mind to study without classification, or even to 

 give distinct single names to. To facilitate these objects, an admirable 

 system, invented by Linnaeus, has been universally adopted, viz. one com- 

 mon substantive name is given to a number of species which resemble each 

 o^her more than they do any other species ; the species so collected under 

 one name are collectively called a Genus, the common name being the 

 rieneric name. Each species is then distinguished from the others of the 

 same genus by the addition of an adjective epithet or specific name. Every 

 species has thus a botanical name of two words. In Latin, the language 

 usually used for the purpose, the first word is a substantive and designates 

 the genus; the second, an adjective, indicates the species. In English, the 

 adjective or specific name conies before the substantive or generic one. 



181. The genera thus formed being still too numerous (above 6000) for 

 study without further arrangement, they have been classed upon the same 

 principles ; viz. genera which resemble each other more than they do any 

 other genera, have been collected together into groups of a higher degree 

 called Families or Natural Orders, to each of which a common name 

 has been given. This name is in Latin an adjective plural, usually taken 

 from the name of some one typical genus, generally the best known, the 

 first discovered, or the most marked (e. g. Ranunculacece from Ranunculus). 

 It is rendered in English by the addition of the word plants to a plural ad- 

 jective, or by adding the word family or order to the name of the typical 

 genus taken adjectively, as Ranunculaceous Plants, or the Ranunculus 

 Family (or Order). This is, however, for the purpose of study and com- 

 parison. To speak of a species, to refer to it and identify it, ajl th$t 19 

 oesessary is to give the generic and specific nameg. 



