OUTLINES OF BOTANY. • xix 



3. Small, globular, oblong or even linear veslolei?, filled with oil imbedded in the substance 

 itaelf o! leaves, bracts, floral organs, or fruits. They are often very numerous, like transparent 

 dots, sometimes few and determinate in form and position. In the pericarp of Vmhellifcnc they 

 are remarkably regular and conspicuous, and take the name of vitta. 



i. Lobes of the disk (137), or other small fleshy excrescences within the flower, whether 

 from the receptacle, calyx, corolla, stamens, or pistil. 



Chap. II. Classification, ok Systematic Botany. 



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



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 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 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 LinnEeus, has been universally adopted, viz. 

 one commen 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. Bach 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. 



181. The genera thus formed being still too numerous (above 6,000) 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 and ITatural Orders, to each of which a common name 

 h9,s 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 iion\ Ranunculus) . 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. iNatural Qrders 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 

 intermediate classification is carried still further. The names of these several groups the most 

 generally adopted are as follows, beginning with the most comprehensive or highest : — 



Classes. Genera. 



Subclasses or Alliances Subgenera. 



Natural Orders or Families. Sections. 



Suborders. Subsections. 



Tribes. Species. 



Subtribes. Varieties. 



Divisions. 

 Subdivisions'. 



183. The characters (3) by which a species is distinguished from all other species of the same 

 genus are collectively called the speciAc character of the plant ; those by which its genus is 

 distinguished from other genera of the Order, or its order from other Orders, are respectively 

 called the generic or ordinal character, as the case may be. The habit of a plant, of a species, a 

 genus, etc., consists of such general characters as strike the eye at first sight, such as si?e, 

 colour, ramification, arrangement of the leaves, inflorescence, etc., and are chiefly derived from 

 the organs of vegetation. 



184. Classes, Orders, Genera, and their several subdivisions, are called natural -v/hen, in 

 forming them, all resemblances and differences are taken into account, valuing them according 

 to their evident or presumed importance ; artificial, when resemblances and differences in some 

 one or very few particulars only are taken into account independently of all others. 



