FRUITS, SEEDS & SEED DEVELOPMENTPacket #73

Chapter #30

INTRODUCTION

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A fruit is a mature ovary

As the seed develop, the wall of the ovary thickens

The thickened wall becomes the pericarp.

As the ovary grows, the other flower parts whither away

Fruits protect the seeds and aid in dispersal.

Figure 30.8Page 599

ADAPTATIONS IN FRUIT

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Dandelions & Maple Trees Wind dispersal is

observed Fruits are described as

kites or propellers. Thistles & Grasses

Animal dispersal is observed

Fruits are described as hitchhickers or burrs.

Animal dispersal often provide resources such as fecal material that fertilize the young sporophyte plant.

Figure 30.9Page 599

CLASSIFICATION OF FRUITS

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Simple Fruits Single ovary Can be fleshy or dry

Cherry Soy bean pod

Aggregate Fruits Arise from a single

flower with several carpels

Blackberry Multiple Fruits

Arise from an inflorescence

Many flowers As the walls of the many

ovaries thicken, they fuse and become one fruit

Pineapple

THE SEEDPART IIChapter 38

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STRUCTURE OF MATURE SEED

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If a common bean seed, a eudicot, is opened, several structures are observed Hypocotyl Radicle Epicotyl Plumule Seed coat endosperm

“EVOLUTIONARY” ADAPTATIONS TO SEED DORMANCY & GERMINATIONChapter 38

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INTRODUCTION I As the seed matures, it dehydrates until only

about 5 – 15% of its weight is water Enters dormancy

Period of extremely low metabolic rate and suspended growth and development

Increases the chance that germination will occur at a favorable time

Species dependent environmental cues break dormancy Fire; light; water; temperature; digestion through

animal’s gut Sexual reproduction produces seeds with

dispersal and dormancy abilities.

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SEED GERMINATION

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GERMINATION I

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Water HAS to be absorbed Causes the seed to swell

and rupture seed coat Triggers metabolic

changes in the embryo promoting growth

Radicle (embryonic root) emerges first from the germination seedlings

Hypocotyl pushes way up through the soil Protecting fragile shoot

apex and large cotyledons

Epicotyl spreads “true leaves” and begin photosynthesis

GERMINATION II

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Cotyledons “seed leaves” whither away.

Seedling is vulnerable to many hazards and only a small number survive.

REVIEW

REVIEW

Students List potential examination questions and/or here,

and on following slides, based on the packet.