Gary Cobb, age 11, of Ashland, Va., for his question:

WHAT MAKES GRASS GREEN?

Grasses can be put into six divisions: grazing and forage grasses, turf grasses, ornamental grasses, cereals, sugar cane and woody grasses. And they are classified as either annual or perennial. Annual grasses die at the end of each growing season, and new seeds must be planted at the beginning of the next season. Perennial grasses live throughout the year.

Grass is one of the largest plant families on earth. Some kind of grass can be found on the land surfaces of every continent. it grows on the desert and in swamps as well as on snow covered mountains and on rocky ledges.

Grass, as well as almost all plants, is usually green because of a green colored material it contains called chlorophyll. Through a process called photosynthesis, chlorophyll helps change sunlight into energy that the plants can use.

Many landscapes are made more beautiful by the use of ornamental grasses. And other types of grasses play important roles in our diets.

Cereal grasses such as corn, barley, wheat and oats are used to make bread, breakfast foods and other food products. And most of the sugar we eat comes from a type of grass plant called the sugar cane.

A grass plant has two parts: the vegetative organs and the floral organs. The vegetative organs include the roots, stem and the leaves. They keep the plant growing. The floral organs are the parts from which the flowers develop. They include the stamens, or male flowers, and the pistils, which are the female flowers. The floral organs produce the seeds from which new grass plants grow.

Grass leaves are called two ranked because each leaf grows on the opposite side of the stem from the leaf below it.

Grass has threadlike roots. Some grasses, such as the common Bermuda grass, have creeping stems that grow below the ground called rhizomes and creeping stems that grow above the ground called stolons. Rhizomes and stolons spread out from the plant to start new plants. The stems, where the leaves and flower clusters grow, are called culms.

Tallest growing of the grasses is the bamboo, which is in the woody grass division. It can grow as high as 120 feet and can be from six to 12 inches thick at the bottom. Stems, with the solid nodes removed, can be used as water pipes and the material is also extensively used for building houses, rafts, furniture and bridges.