INTRODUCTION. 
V 
constitute a family or kind : thus, for example, the various 
species of roses constitute a well known genus, at once dis- 
tinguishable to the most superficial observer. By varieties is 
of course understood any deviation in a particular species from 
those ex:ternal characters which mark the other individuals of 
the same species, many familiar examples of which will occur 
in the course of this work. According to LiimaBus, a plant 
consists of a root, trunk, leaves, props, fructification, inflores- 
cence, and habit. 1. The root consists of two parts; the 
caudex or stump, which may be either solid as in trees, bul- 
bous, as ill tlie lily, or tuberous, as the carrot, potatoe, &c. ; 
the radicula, which is the fibrous part of the root, by which it 
receives nourishment from the ground. 2. The trunk is the 
part which rises immediately from the caudex, and produces 
the leaves, flowers, and fruit ; it is either herbaceous, shrubby, 
or arborescent. 3. The leaves are either simple or com- 
pound, and are distinguished by their situation, insertion, &c. 
4. The props are those external parts which strengthen, sup- 
port, or defend the plant, as the tendrils of some, and the 
thorns of others, 5. The fructification or mode of fruit 
bearing, consists of the calyx, corolla, stamina, pistillum, peri- 
carpium, semiiia, and receptaculum. 6. The inflorescence, or 
mode by which flowers are joined to their several peduncles. 7. 
The habit or external appearance, applied to the agreement of 
j)lants of the same genus, or natural order. To these may be 
added the hybernaculum, or winter lodgement, which is the part 
of a plant that defends the embryo, or future shoot, from injury 
during the winter, and is either a bulb, as in the lilly, tulip, 
&c., or a bud, which is the embryo of the plant, seated on the 
stem of the branches. In general there are three sorts of buds ; 
that containing- the flower only, as in poplar, ash, &c. where 
the leaf-bud and flower-bud are distinct ; that containing the 
leaves only, as in birch ; and that containing both flowers and 
leaves, as in the generality of plants. The generic characters 
of Linnasus are taken exclusively from the seven parts of 
fructification, viz. the calyx, corolla, stamen, pistillum, peri- 
carpium, semina, and receptaculum. 
These several parts we shall briefly describe : 1. The 
calyx, or cup, is the termination of the outer bark of a plant. 
Its chief use is to enclose, support, and protect the other 
