Even today when humans cry or sweat it's saltwater that comes out.
Humans can go for weeks without eating, but only for a few days without drinking.
The situation is often even more extreme for most, but not all, plants. The topic of roots is an important one, for roots are the means by which most land plants acquire their water. Roots grow through the soil, soak up what water they can, and transport that water to the plant's other parts. Obviously, plant roots, in order to find so much water in a place where there doesn't seem to be much of it, must be doing something special. When a typical plant sends down roots, it's not at all like digging a well down to the water table.