I. The Simple Fruits (page 2)

A simple fruit always develops from a single ovary containing one or more carpels and may or may not include additional modified accessory floral (perianth) structures. In addition, a simple fruit is either fleshy or dry. Fleshy fruits are often edible and are seen in the fresh fruit and vegetable section of your local super market. Fleshy fruits include the berry, drupe, pome, pepo, and hesperidium.

A. Simple Fleshy Fruits

 1. The Berry

 Grapes and tomatoes are classified as berries because the ovary wall of the carpel becomes almost completely fleshy at maturity. The number of carpels in each species varies from one to several and their skins can be thin and tender or thin and tough. The number of seeds also varies from one per carpel to many per carpel. The seeds of all berries, are embedded in the fleshy tissue of the carpel.

 2. The Hesperidium

 

  Hesperidium type fruits are always covered with a leathery rind and the partitions separating their carpels are tough and fibrous. The orange, lemon and grapefruit, all members of the citrus family, are good examples of the hespiridium type of fruit.

    3. The Pepo

 

 
 The pepo is covered by a rind that is hard and thick. The cucumber, pumpkin and watermelon are good examples of the pepo type of fruit. Below the rind, the the rest of the ovary wall is soft and fleshy. In the photographs above seeds fill the locule of each carpel.

 4. The Drupe
 
   
If a fruit is fleshy and it has a hard stony pit containing a seed it is classified as a drupe. Drupes are covered by a thin skin derived from the outer tissue layer of the ovary. The soft fleshy tissue below the skin is derived from the middle layer of the ovary and the hard stony pit is derived from the inner tissue layer of the ovary. Cracking the pit open reveals a single seed formed from an ovule contained within the ovary of the flower. Coconuts have fibrous walls instead of the fleshy walls found in most drupes.

5. The Pome
The pome consists of tissue derived from the ovary and from the perianth. For this reason it is often called an accessory fruit. In the example (apple) the core is composed of modified tissue from the ovary wall while the pulp is composed of tissue from the base of the floral tube and receptacle. The seeds were once, early in development, ovules containing fertilized eggs and endosperm. The pear is another pome type of fruit.

Click here to continue the lesson on page 3