PLANT SCIENCE UNIT 2

Fruits

Fruit

In flowering plants – fruit is a mature ripened _________ that contains the seeds

A fruit is defined as a ripened ovary

Pericarp – the ovary wall May consist of two or

three layers: exocarp, mesocarp, endocarp

Pericarp

Fruit Types

SimpleAggregateMultiple

Simple Fruit

A simple fruit – develops from a single ovary of a single flower

Can be either fleshy or dry when matureSimple fleshy fruit

Berry

Simple Fleshy Fruit

1. Berry – entire fruit wall is soft and fleshy at maturity. Inside is slimy. Contains no stony layer but contains one to many seeds.

1. Examples: Grapes, tomatoes, etc

2. Hesperidium - a berry with a tough, leathery rind (peel)

2. Examples: Oranges, lemons, other citrus

Simple Fleshy Fruit

3. Drupe – outer part of fruit wall is soft and fleshy, inner part is hard and stony. Has a pit.

3. Examples: Peach, plum, cherries

Simple Fleshy Fruit

4. Pepo – also a fleshy fruit with a tough outer rind

All members of the squash family: pumpkin, melon, cucumber

Simple Fleshy Fruit

5. Pomes: most of the fleshy part of pomes develops from the enlarged base of the perianth (corolla and calyx) that has fused with the ovary wall

Examples: Pears, apples

Simple Dry Fruits

Simple dry fruits are dry (not fleshy) at maturity. Simple dry fruits that open at maturity include capsules and legumes

Capsule – fruit is dry at maturity and splits open along several seams Example: Cotton

Simple Dry Fruit

Legumes are dry at maturity and split open along __________ seams Examples: pea pods, bean pods, peanut

Simple Dry Fruits

Simple dry fruits that do NOT open at maturity include:Caryopsis: seed coat is

fused to the ovary wall Examples: corn, wheat

Nuts: single-ovary wall and seed coat remain separate, ovary wall is very hard Example: acorn s

Aggregate Fruit

An aggregate fruit develops from one flower with many separate pistils/carpels, all ripening simultaneously Examples: strawberry, raspberry, blackberry

Multiple Fruit

Multiple fruit develops from ovaries of several flowers borne/fused together on the same stalk Example: pineapple

What is the purpose of the fruit?

The main function of the fruit is to disperse the seeds

Dispersal is important because It spreads the progeny in order to colonize new

environments Reduces the chances of predators destroying all of the

plant’s yearly seed production Reduces plant competition

4 types of dispersal

Self Dispersal

Plants disperse their seeds by forceful ejection – explosive fruits!

Witch hazel, squirting cucumber (jet propulsion)

Self Dispersal

The peanut plant sows (buries) its own seeds!

Geocarpic: carpel grows inside the earth

Wind Dispersal

Fruit and seeds may have special devices for wind dispersal

Plumes catch wind currents: dandelionTrees take advantage of their great heights

for wind dispersal. Fruits with wings are used to slow the descent to land: maple, ash fruit

Water Dispersal

Fruits and/or seeds use flotation devices to travel by water

Fruit may have air spaces, waterproof coverings, and corky floats Example: coconuts

Animal Dispersal

Some dry fruit attach and cling to animalsSome have velcro-like hooks that cling to

animal fur (burdock, cockleburs)Others that sticky substances that stick to

host (mistletoe)

Check it out!

http://www.vtaide.com/png/seed-dispersion.htm

Gives more examples of how specific fruits are dispersed