OUTLINES OF BOTANY. XXXV11 



comparison of each plant with those most nearly allied to it. The descriptions 

 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 Mace. 



179. A Variety can only be propagated with certainty by grafts, cuttings, 

 bulbs, tubers, or any other method which produces a new plant by the develop- 

 ment of one or more buds taken from the old one. A Mace may with care be 

 propagated by seed, although seedlings will always be liable, under certain 

 circumstances, to lose those particulars which distinguish 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 numerous 

 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 common substantive name 

 is given to a number of species which resemble each other more than they 

 do any other species ; the species so collected under one name are collectively 

 called a Genus, the common name being the generic 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 specific name comes before the sub- 

 stantive 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 ad- 

 dition of the word plants to a plural adjective, or by adding the word family 

 or order to the name of the typical genus taken acljectively, as Ranunculaceous 

 pi ants or the Ranunculus family (or order). This is however for the purpose of 

 study and comparison. To speak of a species, to refer to it and identify it, all 

 that is necessary is to give the generic and specific names. 



182. Natural Orders themselves (of which we reckon near 200) are often 

 in the same manner collected into Classes ; and where Orders contain a large 

 number of genera, or genera a large number of species, they require further 

 classification. The genera of an Order are then collected into minor groups 

 called Tribes, the species of a genus into Sections, and in a few cases this inter- 

 mediate classification is carried still further. The names of these several groups 

 the most generally adopted are as follows, beginning with the most comprehen* 

 sive or highest : — 



Classes. Tribes. 



Subclasses or Alliances. Subtribes. 



Natural Orders or Families. Divisions. • 



Suborders. Subdivisions. 



