Maria Lopez, age 14, of Jamestown, N.Y.. for her question

HOW MANY KINDS OF LILY ARE THERE?

Lily is the common name for the order Liliales, a large and diverse group of flowering plants that have long, narrow leaves and often showy flowers. It is one largest orders of plants, containing about 8,000 species placed in 20 different families.

Many members of the order are important a food (onions, yams); as ornamental plants (lilies, daffodils, tulips); as fiber (sisal); or as flavoring (sarsaparilla).

Actually, the lily order contains a diverse array of plants that include herbs    climbing shrubs, succulents, acquatics and trees. Stems are usually fleshy in all types. They rise from underground storage organs and bear characteristically narrow leaves with parallel veins.

The lily order occurs throughout the world but most of its members flourish only in subtropical and temperate areas.

Many members of the Liliales show adaptations to arid climates. During unfavorable periods, food and water are stored in a variety of underground structures including bulbs, corms, rhizomes and tubers. Above ground structures such as stems and leaves may also act as storage organs by having thickened bark or epidermal layers to prevent water loss.

Many plants in the group have asexual means of reproducing, including the production of bulblets on parent bulbs or on inflorescences (flower clusters) and the production of seeds by parthenogenesis.

Liliaceae, or the lily family, is the largest in the order with some 200 genera and 2,500 species. It includes such important plants as tulips, lilies, hyacinths and day lilies.

The onion family, Alliaceae, is intermediate in structure between the lily and amaryllis families, combining the superior ovary of the former with the umbellate inflorescence of the latter. It is a medium sized family with about 700 species, usually with bulbs or corms underground and long, slender leaves starting at the ground.

In the asparagus family, Asparagaceae, the leaves are reduced to tiny scales and the needlelike "leaves" are actually highly modified branches. Tender young shoot tips of Asparagus officinale are eaten as a delicacy. Asparagus fern is another species.

The yam family, Dioscoriaceae, is a medium sized tropical and subtropical group with about 650 species. Most are weak stemmed vines with large, underground food storage organs    tubers or rhizomes. Yams are edible tubers of several cultivated species of the genus Dioscorea. Sweet potatoes, Ipomoea batatas, are called yams in the southern United States but are unrelated to true yams.

The agave family, Agavaceae, containing about 700 species, includes many succulent plants of the tropics and subtropics. The typically long, stiff leaves are usually basal, meaning they rise from the base of the stem. They often yield useful fibers. Sisal hemp is derived from Agave sisalana, a native of Mexico. True hemp comes from an unrelated plant, Cannabis sativa.

The water hyacinth family, Pontederiaceae, has bout 35 species of freshwater plants.