256 BOTANY. 
noticed is, that plants are farther divided into genera , and 
species , with their varieties. By species we understand indi¬ 
viduals Avhich compose the genera, or general family; and each 
of Avhich has a specific name. And the genus comprehends 
several species, so essentially different in formation, nature, and 
some adventitious qualities, from other plants, as to constitute 
a distinct family or kind. To illustrate this distinction, we may 
refer to the fact, that, in the human race, some are distinguish¬ 
ed from all others by a generic or family name, as Smith,White, 
Brown, &c. But, in order to identify individuals in these fami¬ 
lies or genera, we have to give a specific name to each individ¬ 
ual : thus, when we refer to individuals or species in these fam¬ 
ilies, we say, John Smith, Thomas Smith; or John White, 
Thomas White ; or John Brown, Thomas Brown, &c. Thus 
we have the genus in the family name, and the species in the 
name of the individual. It is just so in plants; the genus or 
family name rosa includes all roses ; the genus salix or willow 
comprehends all willows; and the genus iris or flag includes 
all the flags. 
The marks upon which the genera of plants are founded, are 
always taken from the shape, position, number, or some other 
property of the different parts of the flower, as the calyx, pe¬ 
tals, seeds, seed-vessels, &c., as whether they be round, or 
heartshaped; whole, or divided; rough, or smooth; single, or 
many; and the like. But the marks by which the species or 
individuals are known, are formed upon the leaves, stems, roots, 
or any other parts of the plant, except the flower. 
