Take a leaf and crush it between your fingers. A pale liquid will come out. This is called sap, and it is mostly water. It shows you that the plant contains water.

It is important to know what wilting is if you are to look after plants properly.

Leave the plant on the window ledge and do not water it. Keep an eye on it at the start and end of each day. Look for signs of wilting. As soon as the plant begins to wilt, feel the leaves and see how limp they are.

Water the plant quickly before any damage is done.

Suppose your plant dries out and does not wilt? Then it is likely that you have bought a plant that normally lives in a part of the world where it is naturally dry for part of the year. Because of this the plant knows how to protect itself. Many houseplants are of this kind because growers know they will last better in customer's homes.