Tropism in some Exotics-Araucaria and Eucalyptus

The trees growing in their natural habitat display perfect harmony with their environmental factors (stimuli), but, when they are grown away from their 'home' into an 'alien' land they may respond characteristically to the effect of certain external stimuli. The new place may be an apparently isoclimatic region and several species may feel perfectly at home, but still, some other species are likely to exhibit sensitivity towards some stimulus or the other by bending towards one particular direction. The effect has been studied on certain species of Araucaria and Eucalyptus which show a tendency to bend towards the east or south. These are, however, preliminary studies and observations and experience of other workers would be welcome.