11

PLANT REPRODUCTIONPLANT REPRODUCTION

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PHOTOPERIODISMPHOTOPERIODISM• The critical factor that

influences flowering is the number of hours of uninterrupted hours of darkness, not the number of daylight hours.

• The flowering response is called photoperiodism.

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PHOTOPERIODISMPHOTOPERIODISM• The beginning of

flower development for each flowering species of plant is in response to the number of hours of darkness.

• This is called the plant’s critical period.

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PHOTOPERIODISMPHOTOPERIODISM• Flowering plants are

placed into four different flowering groups:

1)Short-day plants2)Long-day plants3)Intermediate-day

plants4)Day-neutral plants

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PHOTOPERIODISMPHOTOPERIODISMShort-Day Plants•These plants flower when their number of hours of darkness are greater than their critical period.•These plants flower in the fall, winter, and spring.

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PHOTOPERIODISMPHOTOPERIODISMLong-Day Plants•These plants flower when their number of hours of darkness are less than their critical period.•These plants flower in the summer.

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PHOTOPERIODISMPHOTOPERIODISMIntermediate-Day Plants•These plants flower when their number of hours of darkness are not too great or too few.•These plants flower in tropical regions.

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PHOTOPERIODISMPHOTOPERIODISMDay-Neutral Plants•These plants flower regardless of the number of hours of darkness as long as there is enough photosynthesis to support growth.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Pollination occurs when the pollen grain of a species of plant lands on the female reproductive structure of the same species.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

The pollen grain then grows a pollen tube through the style of the plant into the ovary where fertilization occurs.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Once fertilization occurs, a seed develops.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Parts of Seeds•Endosperm – a tissue that provides nourishment for the embryo.•Seed Coat – Protective outer covering of the seed.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Germination-When the embryo in a seed starts to grow.

Germination begins when the seed absorbs water either as a liquid or as a gas and the seed swells, breaking the seed coat.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Plants can be identified as monocots or dicots by comparing seed, flower, and leaf structure.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Monocots•Petals in multiples of 3•Leaves have parallel veins and are long and narrow.• Seed has a single cotyledon

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Dicots•Petals in multiples of 4 or 5•Leaves have a netted, veined pattern.•Seed has two cotyledons

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Fruits form primarily from the ovary wall, and in some cases the ovary wall and some flower organs.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Types of fruits:1)Simple fleshy fruits2)Aggregate fruits3)Multiple fruits4)Dry fruits

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Simple fleshy fruits•These fruits contain one or more seeds•Examples are peaches, apples, and tomatoes.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Aggregate fruits•Formed from flowers with multiple female organs that fuse as the fruit ripens.•Examples are strawberries, raspberries and blackberries.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Multiple fruits•Form from many flowers that fuse as they ripen.•Examples are figs and pineapples.

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SEED AND FRUIT SEED AND FRUIT DEVELOPMENTDEVELOPMENT

Dry fruits•When mature, these fruits are dry.•Examples are nuts and grains.