32 INTRODUCTION. 



The Fruit. 



The fruit is composed of the ovary and its contents, arrived at maturity 

 and usually changed in texture. It consists of two parts, the covering peri- 

 carp or seed vessel, and the seeds. When the floral envelopes are not adherent 

 to the ovary, they usually wither or fall off soon after fecundation ; but when 

 coherent they become a part of the fruit. Thus in the apple and pear, the 

 most of the bulk consists of a thickened and fleshy calyx ; but the mass is 

 sometimes made up from other organs as in the strawberry, in which the 

 pulp is an enlarged and fleshy receptacle, &c. 



A Pericarp is almost always present, though sometimes very thin, as in the 

 umbelliferous plants, but may be wholly wanting as in the Pine Tribe. The 

 part by which it is attached is called the base, and the other extremity the 

 apex,- the imaginary line passing from one of these points to the other is 

 called the axis. When there is a real axis it is called a columella. This is 

 formed by the extension of the peduncle or by a cohering placenta. When the 

 pericarp consists of two parts, the outer is called the epicarp, and the inner 

 the endocarp or p>utamen ; when it consists of three portions, the intermediate 

 is usually pulpy or fleshy and is termed sarcocarp or mesocarp ; thus in the 

 cherry the skin is the epicarp, the flesh the sarcocarp, and the hardshell con- 

 taining the seed the endocarp. 



A pericarp consisting of one cell is called unilocular ; of two cells, bilocu- 

 lar, &c. The cells are separated by partitions called dissepiments. As the 

 fruit is only a matured pistil, it should agree in structure with it, but some 

 alterations occasionally occur in consequence of the abortion or obliteration 

 of parts, or of the irregular growth of others. Thus a many-celled ovary 

 may afford a one-celled pericarp ; as in the oak, where the ovary is three-celled 

 with a pair of ovules in each, whilst in the acorn there is but one cell and a 

 single seed. On the other hand, the fruit sometimes has more cells than 

 existed in the ovary, as in the Stramonium in which a two-celled ovary be- 

 comes a four-celled pericarp, caused by the growth of the placenta on each 

 side, so as to reach and connect with the dorsal suture. When the mature 

 fruit does not open spontaneously to permit the escape of the seed, it is called 

 indehiscent ; when it opens to discharge its contents it is termed dehiscent, 

 and the pieces into which it divides are denominated valves. Pericarps formed 

 of a single carpel, have two marked lines on their surface, by which they 

 readily dehisce; one is called dorsal, and occupies the place of the midrib of 

 the leaf become a carpel ; the other is termed ventral, and answers to the 

 lines of union of the margins of the leaf. In a many-celled pericarp, each 

 cell or carpel has these sutures more or less distinctly marked. 



The dehiscence is loculicidal when the pericarp bursts vertically at the 

 back of the cells or by the dorsal suture; it is septicidal when it bursts longi- 

 tudinally through the dissepiments, and usually by the ventral suture. Some- 

 times the dissepiments remaining coherent in the axis separate from the valves; 

 this form is called septifragal. Occasionally the dehiscence is transverse, 

 taking place across the sutures, the upper part falling off like a lid; this is 

 called czrcumscissile. The pericarp may also open by pores, or irregular 

 openings at or near the apex. There are several other irregular varieties of 

 dehiscence, but they do not require particular notice. W T hen the pericarp has 

 lateral appendages like wings, it is said to be dipterous, tripterous, SfC, ac- 

 cording to their number; where there are none, it is apterous. 



The pericarp is of various forms, and these have been named as follows : 



