Development of Fruit
Concurrent with the development of the seed(s), the ovary is transformed into a fruit. The fruit protects the seeds and allows their release or germination. In primitive families such as the Magnoliaceae the fruit opens while still on the plant and the seed itself is the unit of dispersal. However, in most of the flowering plants the function of dispersal is at least partly transferred to the fruit.
Figure: Cross-section of the fruit of Pyrus malus (diagrammatic representation).
A true fruit develops from the carpel, specifically from its ovary. However, in many so-called fruits, organs or tissues in addition to those of the ovary participate in protection and dispersal of seed. Examples of accessory tissues or organs contributing to fruit formation are many. In strawberry, Fragaria spp. the floral receptacle extends to form the fleshy edible part of the fruit. In apple, Pyrus malus the floral tube formed by the floral organs and the receptacle around the inferior ovary, together constitute the bulk of the fruit. In both these instances the edible fruit is product of carpellary and accessory tissues. On the other hand, in jackfruit, Artocarpus integrifolia the perianth and in pineapple, Ananas comosus the bracts surrounding the flowers in an inflorescence proliferate to contribute to formation of the fruit. Where organs other than gynoecium participate in forming a fruit, the fruit is termed a false fruit or pseudo carp. The wall of a true fruit is termed pericarp. The mature pericarp is often made up of three distinct regions. In mango, for instance, the outer skin or peel represents the exocarp or epicarp. The fleshy and juicy middle portion is the mesocarp. The inner shell or stone is formed by the endocarp. Fruits of different plants display a rich diversity in size, shape, structure, and hardness. Chemical constituents and dispersal mechanisms. From the morphological standpoint they are classified into a few types based on two criteria. The main criterion is the degree of hardness of the fruit wall or pericarp whether it is dry and hard or soft and fleshy. The second criterion is the ability of the fruit to dehisce or remain intact after ripening.