Howard Little Jr., age 10, of Tucson, Ariz., for is question:
HOW MANY KINDS OF CACTUSES ARE THERE
Most cactuses are plants that you'll find growing only in dry regions. There are about 1,000 different kinds and most of them are found only in North America. The plants grow in their greatest abundance in the Southwestern part of the United States and in Mexico.
Cactuses are well suited to places with little rainfall. With most other plants, the food is made in the leaves and the leaves also give off water. With cactuses, however, most of the leaves have disappeared so that the plants may better hold moisture.
Stems of cactuses have taken over the task of making food for the plants. These stems can store water.
Sharp bristles and spines help to protect most cactuses. The spines keep away animals that live on the desert. Were it not for these spines, the cactus plants would be eaten and die out.
Cactus spines grow from parts of the plant called areoles, which look like tiny cushions. The areoles are arranged in definite patterns over the surface of the plants. New branches and flowers also grow, like the spines, from the plant's areoles.
Cactus plants' roots are covered with a corklike bark and they lie close to the surface. They spread far out so they can catch the water from light rains and quick floods that may take place in desert areas. A cactus plant only three feet tall may have roots more than 10 feet long.
Largest cactus in the United States is the saguaro, often called the plant cactus. It actually grows in forests and can also be found in scattered groups in much of the land that drains into the Gulf of California.
Arizona Indians use the dried wood ribs of the saguaro for fuel and for making frames for their houses. They also eat the fruit which ripens in June and July.
Plant breeder Luther Burbank developed a spineless cactus that provides a food source.
Many beautiful cactuses are in the cereus group. Included here is the night blooming cereus. This plant has large, fragrant flowers that open only at night.
People in Mexico find many uses for the cactuses that grow in their country. A flat leaved cactus called the opuntia provides joints that are eaten boiled or fried. And the juicy fruits of this kind of cactus are eaten raw or cooked.
Seeds from many types of cactuses are ground into meal and made into cakes.
Many plant nurseries sell cactuses which can be used as house plants. Many kinds are easy to grow and they adjust to artificial heat better than most other plants.
Nurserymen suggest that cactuses grown indoors should be potted in light, sandy soil. It is important that the plants have good drainage. Also, they shouldn't receive too much water.