JfjV IXTRODUCTKJX T(J BOTANY, 



characters furnished by all the organs of a vegetable, and 

 unites all those, which have the greatest number of points of 

 contact and resemblance. The systems of Tournefort, and 

 of Linnaeus had for their basis only the consideration of 

 a single organ; for example, Tournefort employed the corolla, 

 and Linnaeus the stamens for establishing their principal divi- 

 sions. These systems of Tournefort and Linnaeus, have for 

 their object the discovery of the name of a plant, A\ithout 

 giving ideas of its organization. The study of the natural 

 system, and families of plants gives more precise ideas respect- 

 injr the structure and orjjanization of the different veffetabies. 



Jussieiis Method of Natural Families. 



The plants arranged by this system of families, have closer 

 affinities with those which immediately precede or follow them, 

 than with any other. This system unites and arranges plants 

 in groups and families, according to the greatest number of 

 their common characters. The embryo of the seed furnishes 

 the foundations of Jiissieu's divisions, the stamens and pistils 

 occupy the second rank. Stems, leaves, and roots, supply 

 accessary characters. 



In explaining the means b}' which vegetables have been 

 united into natural groups or families; we will first give an 

 idea of the words species, variety, gemts, order, s.x\(\ family. 



A species is a collection of individuals which constantly re- 

 produce each other of the same form. Tlie seed of any given 

 species will produce an individual, perfectly similar to itself. 

 Species which exhibit some differences in respect to the colour 

 of their flowers, or of their more or less considerable stature, 

 constitute varieties, which may be distinguished from species, 

 in this respect^ that in a state of nature, they are not repro- 

 duced from seeds with all their characters ; for example, the 

 flowers of the lilac are usually light violet; but sometimes 

 xsohite, without any corresponding change in any of its other 

 characters : here, the xvhite lilac is merely a variety of the 

 violet flowered one. 



A genus consists of a more, or less considerable number of 

 species, united by common characters, taken from the organs 

 of fructification, but all distinct from each other by specific 



