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It is very difficult for living things to survive in the desert because most deserts are dry and hot. There may not be any rain for months. And when it does rain, the hot, dry weather makes the water quickly evaporate. Without clouds there is not much shade from the Sun. A desert plant like cactus, must adapt to the harsh desert conditions in order to stay alive and grow.
The needles on a cactus are called spines and are actually a kind of leaf. These spines help the cactus survive in the desert. There are different kinds of cactus spines. Some of the spines help the cactus collect rain. They direct water to the cactus's roots.
Other kinds of spines grow thickly over the cactus. They protect it from the Sun and help stop the cactus from drying out. Water doesn't evaporate as fast if the Sun is not shining directly on the cactus's skin.
Still other kinds of spines protect the cactus from animals looking for a juicy meal. The spines break off easily and stick in an animal's mouth if it tries to eat the cactus.
Some spines even help the cactus reproduce. For example, the jumping cholla breaks apart when an animal brushes against it. These spines stick to the animal. When the cactus piece finally drops off, it grows roots and becomes another plant.
WordList
evaporate : turn from liquid to gas
spine : a stiff, sharp needle of a cactus
harsh : strong, diffi cul
You Practice
I. Answer the following questions.
1) Why are there not many plants or animals in the desert?
2) How does a cactus adapt to life in the desert?
3) What do different kinds of spines on a cactus do?
4) What happens if an animal tries to eat a cactus?
5) How does the jumping cholla help the cactus reproduce?
II. Opposites—Find words in the reading that are the opposite of these words.
1) die: s _ _ _ a _ _ _ _
2) nice, pleasant: h _ _ _ _
3) dry: j _ _ _ _
4) thinly: t _ _ _ _ _ _
5) the same: d _ _ _ _ _ _ _ _
III. Read these sentences carefully. Write Yes or No for each one.
____ 1) All spines on the cactus help it reproduce.
____ 2) Water evaporates very quickly in the desert.
____ 3) Deserts don't get a lot of rain.
____ 4) Some spines protect the cactus against animals.
____ 5) Spines are actually a kind of leaf.