Flower structure

Pollination

Angiosperm life cycle

Fruits

Seeds

 

 

Fruits can take on many shapes and texture. Part of the answer of why they are shaped as they are ties in with how many flowers are involved in the production of that fruit.
Other answers to shape may relate to how much energy they have to invest into fruit production ( perennial vs annuals and their accumulated supply of energy over time).
Whether they produce fleshy vs dry fruits may depend on who they are trying to attract to disperse their fruit, and whether they expect that seed contained within to stick around for a long time or short. As a generalization.. larger fruits and seeds tend to be short lived while dry smaller seeds tend to have a longer live span ( years to decades to centuries).
There are many theoretical questions that could be probed with respect to strategy, but below we'll just deal with the nitty-gritty facts about the types of fruits. However as you read through. rationalize why that species or more likely family evolved the fruit form they did.
Also try to figure the budgetary cost of producing such fruit. In some way though we need to be cognizant of the fact that the fruit you see today was also selected by humans for the last thousand years and the largeness of the forms is unlike the original forms.

 

FRUIT COMPOSITION

Simple = from a single pistil ( stigma + style + ovary) such as an apple

 Aggregate = from a cluster of ovaries on a common receptacle or flower ( raspberry)

Multiple = from a cluster of flowers on a common receptacle as in a pineapple

 

FRUIT TEXTURE

fleshy = pericarp soft & fleshy upon maturation

dry = pericarp is papery, leathery or woody upon maturation

dehiscent - ripe fruit splits open

indehiscent - ripe fruit does not split open

True fruit - composed of only the ripened ovary, with its contained seeds (pea, tomato, lily)

Accessory fruit - composed of the ripened ovary + additional parts, such as receptacle, bracts. (apple, cucumber, strawberry)

The tomato an example of a berry

Simple fleshy

A. Berry

  • multiple carpels
  • soft, fleshy throughout i.e. tomato, bell pepper, grape

Specific types in addition to the simple berry:

  • hesperidium
    • leathery rind
    • pulp separated into compartments i.e. orange, grapefruit
  • pepo
    • accessory fruit
    • receptacle tissue fuses with ovary i.e. cucumber, squash

B. Drupe

  • thin exocarp ( skin)
  • fleshy mesocarp

    hard & stony endocarp (contains toxins) envelopes seed (ovary in seed) i.e. olive, peach, plum, cherry

C. Pome

  • accessory fruit ( see above )
  • 'core line' separates cortex from pith

ovary is at center of core (parchment-like texture that gets stuck in your teeth ) i.e. apple, pear

Simple dry dehiscent

A. Follicle
  • derived from one carpel which splits on its side at maturity i.e. milkweed
  • fibers transport seeds
  • single suture line

B. Legume

  • derived from one carpel and splits on both sides at maturity i.e. beans, peas, peanuts

C. Capsule

  • develops from compound ovary and consists of multiple carpels
  • capsule splits in multiple segments at maturity, splitting lengthwise or by pores (lily, iris,snapdragons,poppy)

D. Silique

  • consists of two fused carpels that separate at maturity i.e. shepherd's purse and mustard fruits

legume on left and capsule on right

silique of mustard

Simple dry indehiscent

A. Achene ( strawberry seed, sunflower seed)

  • once-seeded fruit
  • thin shelled,fruit coat free from seed
  • seeds germinate and breaks open

B. Grain ( wheat, corn)

  • one small seed which fuses to inner layer of pericarp
  • example is corn; each kernel is a fruit

  • corn... each seed is a fruit: grain

C. Samara

  • distinct winged fruit, i.e. maple seed

 

achene on accessory layer

 

D. Nut

  • one - seeded fruit
  • very hard, thick pericarp which may be surrounded by a cup i.e. acorn
  • very hard, thick pericarp may be surrounded by husk i.e. filbert, chestnut, pecan

Aggregate fleshy

  • strawberry and blackberry at maturity
  • individual fruits of strawberry :red part is accessory and little gritty parts are achene seeds
  • blackberry contains cluster of dupes

Aggregate dry

  • magnolia and tulip poplar fruits
  • magnolia contains individual fruits called follicles
  • tulip poplar is aggregate

magnolia cone is a dry aggregate

Multiple fleshy

  • multiple flowers
  • examples are: pineapple, mulberry, and fig

Multiple Dry

  • separate fruits
  • many ovules
  • many flowers
  • consist of cluster of capsules
  • example: sweet gum balls