How does a plant know when to flower

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How does a plant know when to flower?
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Factors that control flowering

• Light (phytochromes)
• Photoperiods
• Signals from the leaves to the buds
• Meristem-identity genes

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Phytochrome regulation of lettuce seed germination
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Phytochrome as a switching mechanism
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Photoperiods

• Plants are able to detect the time of the year or
  seasons by using the photoperiod ( length of
  night and days)
• Photoperiodism is a plant response to a
  photoperiod ie flowering
• There are three different kinds of plants based
  on photoperiodism, they include short day plants
  (ie Chrysanthemuns), long day plants (ie
  lettuce) and day neutral plants ( ie tomatoes,
  rice).

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Critical night length
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How do leaves and buds work together to produce
flowers?

• Leaves detect the photoperiod and buds produce
  flowers
• Leaves sends signals to the buds in order for
  them to develop flowers
• All plants contain a chemical substance that
  induces another plant to flower when they are
  grafted

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Meristem-identity genes

• The buds meristem has to change from a
  vegetative state to a flowering state
• Meristem-identity genes must first recognize that
  the bud will now form a flower instead of a
  vegetative shoot
• Genes that specify the organization of the floral
  organs activate and form the organs (sepal,
  petals, stamens and carpels)