28 NEW YORK STATE MUSEUM 



stigma, sends a tube down through the tissue of the stigma and style and 

 discharges into the ovule a male nucleus which unites with a nucleus in the 

 embryo sac of the ovule, fertilizing the ovule, and stimulating its develop- 

 ment into an embryonic plant. By a process of hardening of the coats of 

 the ovule its development is arrested and the seed is produced. 



The Fruit 



The fruit of a plant (in the case of our flowering plants) consists of the 

 matured pistil (or gynoecium) , including also whatever parts of the perianth 

 or other floral organs may be joined to it. Fruits are of various degrees 

 of simplicity or complexity, and may consist of a matured simple ovary, 

 a cluster of such ovaries, at least when they are somewhat coherent, or 

 a ripened ovary with calyx and other floral parts consolidated with it. 



The pericarp, or seed vessel, is the ripened ovary and should therefore 

 accord in structure with the ovary from which it is derived. In the 

 development of a simple ovary into a simple fruit certain alterations some- 

 times take place, either by the abortion or obliteration of certain parts, or 

 by accessory growth. The dehiscence is the method by which a pericarp 

 opens to discharge its seeds and may be regular (normal) or irregular 

 (abnormal). The word " pod " is frequently applied to dehiscent pericarps. 



A capsule is a dehiscent pericarp formed of two or more carpels. Such 

 carpels are septicidal (figure 80) when the dehiscence is such that the carpel 

 is divided into its constituent carpels. Members of the St John's-wort 

 family afford a good example of this method as do also Rhododendron and 

 Kalmia. Carpels are called loculicidal (figure 79) when each of the compo- 

 nent carpels splits down its dorsal suture, as in Iris, Hibiscus, Oenothera etc. 



Kinds of fruits. For ordinary purposes it is sufficient to classify fruits 

 into four classes: 



1 Simple fruits, those which result from the ripening of a single pistil. 



2 Aggregate, those of a cluster of carpels of one flower crowded into 

 a mass. 



