Post on 07-Jan-2017
Tropism a growth response which a plant
makes with respect to a directional stimulus.
plant movement towards or away from a stimulus.
came from the Greek word “tropos” which means to turn.
TropismPositive Tropism
towards the stimulus
Negative Tropism
away from stimulus
Types of Tropism:1) Phototropism2) Geotropism3) Thigmotropism4) Hydrotropism
Phototropism movement towards or away from lighttropos = to
turnphoto = light
Importance: Increases the probability of stems and leaves intercepting light for photosynthesis
Roots obtain water and dissolved minerals that they need.
Phototropism
Geotropism movement towards or away from the earthtropos = to
turngeo = earth
Importance: Roots will be more likely to encounter water and minerals,
Stems and leaves will be better able to intercept light for photosynthesis.
Geotropism
Thigmotropism movement towards or away from touchtropos = to
turnthigma = touchImportance: Thigmotropism by tendrils allows plants to “climb” objects and thereby increases their chances of intercepting light for photosynthesis.
Thigmotropism
Positive Thigmotropism
Thigmotropism
Negative Thigmotropism
Hydrotropism movement towards or away from watertropos = to
turnhyrdro = water
Importance: This ability to bend and grow the root towards a moisture gradient is essential because plants need water to grow.
Hydrotropism