XXIV 
OUTLINES OF BOTANY. 
Chap. II. Classification, or 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 description of plants here alluded to are 
descriptions of species; thenaturaldivisions of theFlora refer to natural groups of species. 
177. A Species comprises all the individual plants which resemble each other suffi- 
ciently 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 Linnaeus, has been uni- 
versally 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 col- 
lected 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 bo- 
tanical 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, indi- 
cates the species. 
181. The genera thus formed being still too numerous (above 6,000) for study with- 
out 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). 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 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 
