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The tropismes

Tropismes: The responses of plants caused by an external stimulus, which is what determines the direction of movement.
Tropism positive: If the direction is toward the stimulus.
Tropism negative: If the direction is against the stimulus.
The tropismes occur in response to light (phototropic), the severity (geotropisme) and contatcte (tigmotropisme).
In fototropismes, the movement of the plant due to the action of plant growth hormones, the auxin (occur at the ends of the root and stem).
The root growth into the interior of the sun (geotropisme), in response to gravity. Some climbing plants such as vines have tigmotropisme. Is the response of contact with any surface or roll axis and in which aid climbing.

The nasties
Nasties: Movements of plants caused by an external stimulus. Unlike tropismes movements do not occur in a certain direction.
Examples:
- The closure of the petals of some flowers (tulips, daisies at night)
- The movement of the leaves of mimosa when playing them.
- The response of carnivorous plants when they find something insect (the contact makes you close to capture the fast).

The photoperiod and flowering
Photoperiod: Number of hours of light a plant receives (this period depends on many flowering plants)
- Spinach not flourish until the period of daylight is 14 hours.
These types of plants are called long-day (spring and summer)
- Chrysanthemum and the carols or Posets are short day plants bloom and remain until at least 9 consecutive hours of darkness. (autumn) Other (eg.: strawberries, rice and tobacco)
The responses of plants to length of day and night are adaptations to the climatic and geographic conditions in which they live. This ensures that flowering occurs at the time most favorable for pollination.