Tropism
When plants “react”!
Tropism
All living things respond or react to their
environment.
–temperature
–weather
–other organisms
Plants also react to stimuli. This is
called tropism.
What is tropism?
The way a plant behaves due to certain
environments.
Example: Look at your eco-columns.
• Growth towards the sunlight
• Roots always grow down
Sunlight
Plants react to
sunlight. The sides
away from the sun
grow longer and
the plant starts to
bend towards the
light.
Darkness
Other plants may react
from darkness or lack
of light. Morning
glories close up at
night when they react
from the lack of
sunlight.
Gravity
Like everything else on
Earth, plants also
respond to gravity. A
plant’s roots grow
down into the soil due
to the pull of gravity.
This also anchors the
plant into the ground.
Venus Fly Trap
These plants are very different
from normal plants.
1) Since they eat insects and
meat,
they are consumers.
2) They respond to touch.
When something touches
one of its sticky hairs, they
bend and trap the animal
inside.
Touch
Another plant that
responds to
touch is the
mimosa plant.
This Hawaiian
fern plant closes
up when
touched.