Lecture 17 - Fruit

Fruit function

• protecting enclosed seed

• dispersal mechanism

Fruit definition

Mature ovary + accessory parts from surrounding flower

Fruit development

• Flower drops petals

• Ovary grows/thickens

Fruit classification is based on

Developmental origin

Simple fruit

Develops from a single ovary/carpel

Ex. peach, cherry

Aggregate fruit

Several fruits from one flower with many separate carpels, ripening together

Each part of the berry is a single ovary

ex. Strawberries, raspberries

Multiple fruit

Several flowers fused together from the same inflorescence

ex. pineapple

Accessory fruit

“Fruit” derived from plant part other than ovary tissue

ex. Strawberry and apple

Fruit parts - pericarp

1. endocarp - inner

2. mesocarp - middle

3. exocarp - outer
   Not all fruits have all of these layers!

Types of simple fleshy fruit

1. berry

2. hesperidium

3. drupe

4. pepo

5. pome

Berry

Fruit wall is soft and fleshy at maturation, ‘slimy’ inside

ex. tomato, grape

Hesperidium

Berry with tough rind/peel

ex. citrus

Drupe

Fleshy exocarp and mesocarp with hard/stony endocarp

ex. Cherry

Pepo

Fleshy fruit with tougher outer rind

ex. Watermelon

Pome

Fleshy part formed from base of perianth that has fused with ovary wall

Simple dry fruits

Dry pericarp at maturity

Dehiscent and indehiscent types

Dehiscent

Splits open at maturity

includes capsules and legumes

Indehiscent

Do not split open at maturity, usually containing single seed

includes caryopsis and nuts

Capsule

Dehisces at maturity along several seams

Legumes

Dry at maturity and split along two seams

ex. pea pods

Caryopsis/grain

Seed coat is fused to ovary wall

ex. cereal grains

Nut

One seeded fruit with very hard pericarp