xxxvi INTRODUCTION TO BOTANY. 



A vegetable in its perfection consists of a root, stem, leaves, 

 flowers, pistil, stamens, corolla, calyx, fruit; which last is com- 

 posed of the pericarp, and of tlie seed. 



The pericarp, or seed-vessel, is the full grown germen, in 

 which were contained the ovules, (rudimental seeds,) now 

 become perfect seeds. It is composed of three parts; of 1. the 

 epicarp, or outer membrane. 2. of the endocarp, or membrane, 

 which lines its inner cavity, and 3rdly. of the sarcocarp, o. pa- 

 renchymatous substance, situated and contained between the 

 two former mentioned membranes. See Plate 12, and expla- 

 nation. 



The seeds contained in a pericarp, are attached to it by the 

 tropJiosperm, ov placenta : this is formed of vessels, which con- 

 vey nourishment to the seeds. 



The liilum, or umbilicus, (eye, or navel,) is the point on 

 the surface of the seed to which the trophosperm is attached. 

 See Plate, 178. a. 



The arillus, or coat, of the seed, is a peculiar prolongation 

 of the trophosperm, which instead of stopping at the circum- 

 ference of the hilum, is more or less continued over the seed, 

 so as even to cover it completely. 



The seed essentially consists of two distinct parts, 1. epi- 

 sperm, that is, its proper membrane or covering; and 2. its 

 Jternel, or the body contained in the episperm. 



The kernel is essentially composed of the embryo, that is to say, 

 that which tends to be developed and to produce a vegetable 

 similar to that which gave it birth. The Jcernel ?,oxnei\me?, con- 

 tains another body, to which the embryo is applied, or within 

 which it is entirely concealed : this is called the e^idosperm, 

 perisperm, or albiimen : see Plate 12, and Explanation. The 

 embryo is the essential part of the vegetable: it is composed of 

 three parts ; one inferior or the radicular body, which in ger- 

 minating gives rise to the root ; another superior, or the gem- 

 mule, produces the stem, the leaves, and the other parts. 

 Lastly, an intermediate and lateral part, which is the cotyle- 

 donary body, or either simple, or divided into two parts, which 

 are called cotyledons. Hence, the division of vegetables, pro- 

 vided with an embryo, into two great classes, 1. the monoco- 

 tyledons, or those whose embryo has but one cotyledon ; and 



