Fruits and Seeds

Reference:

Plants and People, pages 74; 86-91

On Food and Cooking, pages 181-188; 200-204


Learning Objectives:

What are simple fruits?

What are fleshy fruits?

What are dry fruits?

What are dehiscent fruits?

What are indehiscent fruits?

What are aggregate fruits?

What are multiple fruits?
 

Recall that a carpel is a leaf (sporophyll) that folds over to provide protection for ovules. Fruits develop from the ovary walls (carpel) and flower parts associated with carpels, including the pedicel. The position of the ovary in the flower is an important factor in determining the fruit, so we will review those.

A HYPOGYNOUS ovary is avove the sepals and petals; a PERIGYNOUS ovary is at the same level as sepals and petals and an EPIGYNOUS ovary is below the level of the sepals and petals.

The carpel (ovary wall) develops into a layer called the PERICARP in a fruit. The pericarp has 3 layers, the EXOCARP, the MESOCARP and the ENDOCARP. The texture of these layers determines the fruit type. If parts of the pericarp are fleshy, the fruit is a FLESHY FRUIT. If the pericarp is dry, the fruit is a DRY FRUIT.

SIMPLE FRUITS develop from a single pistil. Since a pistil may itself be simple (one carpel) or compound (more than one carpel fused together), a simple fruit may consist of one or more carpels. When the fruit has more than one carpel, it may have chambers to it, with the chambers called LOCULES.

Simple, fleshy fruits.
 

Berry

Thin exocarp, soft fleshy mesocarp and endocarp. One to many seeds. Tomatoes, grapes, blueberries, and Kiwi fruits are examples.

Hesperidium

Berry with a leathery rind. Oranges, limes, and Grapefruits are examples.

Pepo

Tough outer rind. Rind derived from receptacle (part of flower stem where sepals, petals, stames, carpels come off) and exocarp. Mesocarp and endocarp fleshy. Squash family, that includes pumpkins, melons and cucumbers are examples.

Drupe

Thin exocarp, fleshy mesocarp and stony endocarp enclosing seed. Cherries, peaches and plums are examples.

Pome

Fleshy part from stem of flower (pedicel) that fuses to ovary wall (which is very thin). Ovaries epigynous, so the other flower parts are above the ovaries, that are buried in the pedicel. This fruit occurs in the rose family, and includes fruits such as apples and pears.
 

Simple, dry fruits.
Dehiscent fruits.

Dry fruits may open to release their seeds, wich are dehiscent dry fruits.
 

Follicle

split open along one seam. Examples of plant with follicles are Magnolia and milkweed.

Legumes

Split along two seams. Examples are plants in the legume family, like beans and peas.

Capsules

Open along many pores or slits. Cotton and poppies have capsules.


Indehiscent fruits.

Dry fruits that do not split open.
 

Achene

One seeds dry friuts where the pericarp is separated from the seed. Sunflowers have achenes.

Samara

Achenes where the pericarp forms a wing. Maples have samaras.

Nuts

One seeded fruits with stony pericarps. Oaks produce nuts.

Aggregate fruit

A fruit that develops from many pistils from the same flower. Raspberries, strawberries and blackberries have aggregate fruits.

Multiple fruit

A fruit that develops from the fusion of carpels from many different flowers. Figs and pineapples have multiple fruits.