Drought Resistance
Drought resistance is a plant's ability to stay alive and healthy when water is scarce.
Think of it this way
A cactus-shaped jar sits next to a regular glass on a dry tray. Both start with the same amount of water inside. The regular glass loses water fast — drops seep out from the sides. The cactus jar holds its water tight, sealed with a thick wax coat, staying full long after the glass runs dry.
Explaining drought resistance by grade level
Some plants stay green even when it does not rain for a long time. You can test this by growing rye grass and other types of grass, then not giving them water. Some grass wilts fast. Other grass stays strong much longer.