Life originated and evolved in water. Later the The tropical countries
where the need to under- plants moved out of water, conquered the land
and stand the natural ecosystems is far greater because became dominant
over it. The evolution through they are under intensive pressure from
develop- the millennia resulted in enormous complexity of ment from a
rapidly growing human population, form, tissue organisation,
reproductive mechan- have generally devoted much less attention to the
isms and specialisation of taxa in different niches. studies of aquatic
ecosystems. The Indian subconti- At some stage during evolution, some
plants devel- nent is a well-recognised biogeographic region with oped
appropriate morphological and physiological a distinct geological
history, climate, soils and adaptations and reverted back to the aquatic
and/ biota. It is also distinct in the history of human civilisation and
cultures which have a profound bear- or semi-aquatic habitat. These
plants, perhaps with the exception of a few ing on the natural
ecosystems. This book is in- with beautiful flowers, have attracted
little atten- tended to provide the state of our knowledge of the tion
from mankind. The fact that humans evolved aquatic and semi-aquatic
vegetation in the inland in a tropical forest or savanna environment
appears freshwaters of the subcontinent. The book covers responsible for
a permanent bias in human atti- only the herbaceous vegetation, since
there is al- tudes towards land and its biota.