Plants in the desert – how they grow?

Most plants store water in their roots, stems and leaves.
Each time it rains, they refill their store.
But in the desert it might not rain for many months, or even years.
Then it falls as a short, heavy shower.
When it rains, the shallow, wide-spreading roots of a cactus can soak up the water very quickly, before it evaporates.
The leaves of the cactus become swollen with the extra water. They will act as a water store, supplying the plant with the water it needs. Other desert shrubs send down deep roots to reach groundwater far below the surface.
There are even plants, like the welwitschia of the Namib Desert, that trap the tiny droplets of water which form when the desert fog condenses. The water collects in their twisted leaves and trickles down to the roots.

Watch roots grow
Fill a jar almost full of water. Fix an onion in the neck of the jar. Make sure its base is in the water.
Watch the onion roots grow.