Question

why is folding of leaves of touching sensitive plant with finger not a tropism?

Answer 1

Tropism is a growth movement.
but when we touch the leaves of sensitive plant it start folding because of the water present on the leaves start going from there.
in this process there is no change in the growth of the plant so it isn't tropism.

Answer 2

leaves of Mimosa plant is folded when touched and return to its position after some few minutes. when it is touched it fold himself and its stem droop. this happen in turgor pressure.