Photoperiodism

Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in animals and plants.

Related Topics:
Animal - Plant

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Many flowering plants use the pigment phytochrome to sense seasonal changes in day length, which they take as signals to flower.

Related Topics:
Flowering plant - Pigment - Phytochrome

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Broadly, flowering plants can be classified as long day plants, short day plants, or day neutral plants. Long day plants require a certain amount of daylight to initiate flowering, so these plants flower in the spring or summer. Conversely, short day plants will flower when the length of daylight falls below a certain amount. Day neutral plants do not initiate flowering based on photoperiodism; some may use temperature (vernalization) instead.

Related Topics:
Long day plant - Short day plant - Day neutral plant - Vernalization

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Other instances of photoperiodism in plants include the growth of stems or roots during certain seasons, or the loss of leaves.

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Some birds use photoperiodism to prepare for a migration or for the cold of winter. In some mammals, the time of estrus is regulated by photoperiodism.

Related Topics:
Bird - Mammal - Estrus

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