ABSTRACT
Warming (1909) distinguished three groups of plants on the basis of their water relationships: hydrophytes, mesophytes, and xerophytes. Hydrophytes normally grow in water or swamps—mangrove, bullrush, and paddy rice being good examples. Most field crops belong to the mesophyte group. Paltridge and Mair (1936) further divided mesophytes into two subgroups. Those that wilt permanently after losing 25 per cent of their water content are called true mesophytes; those that wilt after losing from 25 to 50 per cent of their water are xerophytic mesophytes. Xerophytes are capable of enduring even more severe drought. They wilt permanently only after losing from 50 to 75 per cent of their total water content.
