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Q.
Pneumatophores are positively
AMUAMU 2004
Solution:
Pneumatophores are aerial, negatively geotropic roots that act as organs of gaseous exchange. This type of roots are produced by plants growing in saline soils poor in oxygen and characteristic of halophytes, eg, Rhizophora and Ceriops. These are the only roots, which are negatively geotropic and negatively hygrotropic in nature.
Geotropic are plant organs (mainly roots), which grow in response to gravity. Phototropic is growth of plant in response to light. Rheotropic is movement in response to water current.