Laura Davis, age 11, of Santa Rosa, Calif., for her question:

HOW TALL DOES MESQUITE GROW?

Mesquite is a thorny, low shrub which grows in dry climates. The shrub is common in the southwestern part of the United States, in Mexico, the West Indies and parts of western South America. It grows also in the Hawaiian Islands, where it was introduced by missionaries.

When the low mesquite shrub has plenty of water, something almost magical happens: the mesquite grows to be a tree 50 to 60 feet high with a trunk three feet across.

Ordinarily, the mesquite needs and receives very little water, and it remains a low shrub. It grows very well in deserts too hot and dry for other plants. To obtain water, a mesquite may burrow its roots 60 feet into the ground.

People use the wood of the mesquite for fuel, to make fence posts and to erect buildings. The seeds or beans serve as food for cattle and horses and were once an important food for the Indians of the southwest.

Two kinds of gum taken from the mesquite are used to make candies and Mexican dyes.