Lily

Lily, common name for a family comprising more than 250 genera and about 4000 species of mostly herbaceous flowering plants, many with showy flowers. It contains many horticulturally important plants, including tulips, lilies, daffodils, hyacinths, day lilies, and amaryllis. Another important genus, the onion genus, contains about 700 species, usually with bulbs or corms underground and long, slender leaves starting at the ground (basal leaves). Several species are cultivated as food crops: onions and shallots, garlic, chives, and leeks. In the asparagus genus, the leaves are reduced to tiny scales, and the needlelike “leaves” are actually highly modified branches. Tender young shoot tips of asparagus are eaten as a delicacy. Asparagus fern is another species grown as a houseplant for its attractive foliage and for its pretty red berries. The aloe genus also belongs to the lily family and contains about 250 species native to Arabia; Africa, especially South Africa; and Madagascar. The hardy plants are often potted outdoors, and the juice from the leaves has medicinal uses.

The order that lilies belong to is distinguished by having all perianth parts (sepals and petals) relatively undifferentiated and petaloid, a three-chambered gynoecium with nectaries generally present between the chambers (sepal nectaries), and larger seeds with well-developed storage tissue (endosperm) and embryos.

The order contains 15 families, some of which are discussed below, and nearly 8000 species, including herbs, climbing shrubs, succulents, aquatics, and trees. Stems are usually fleshy in all types; they rise from underground storage organs and bear characteristically narrow leaves with parallel veins. The order occurs throughout the world, but most of its members flourish only in subtropical and temperate areas.

Many members of the lily order show adaptations to arid climates. During unfavorable periods, food and water are stored in bulbs or other forms of enlarged underground stem, such as corms, rhizomes, and tubers. Aboveground structures such as stems and leaves may also act as storage organs; they often have thickened bark or epidermal layers to prevent water loss. Many plants in the group have developed asexual means of reproducing, including the production of bulblets on parent bulbs or on inflorescences (flower clusters) and the production of seeds by parthenogenesis.

The pickerel weed family has about 35 species of freshwater plants found throughout the tropics. The water hyacinth floats freely on the water's surface because of its swollen, hollow petioles (leafstalks); due to its rapid growth and lack of natural predators, it has become a troublesome weed in some waterways.

In the iris family, about 1800 species are placed in about 92 genera. The family's horticulturally important plants include crocuses, gladiolus, and irises.

The agave family contains about 18 genera and 410 species; many are succulent plants of the tropics and subtropics, especially common in arid areas. The typically long, stiff leaves are usually basal (arising from the base of the stem) and may yield useful fibers. Sisal hemp is native to Mexico. Other fibers known as hemp are also obtained; true hemp comes from an unrelated plant. The Joshua tree of the American Southwest and the century plant are also members of this family.

The catbrier family contains mostly tropical to temperate herbs and woody climbing or trailing plants. About 225 species are placed in 10 genera. Sarsaparilla is obtained from the roots of some species of the family. Familiar species include carrion flower and the greenbrier or horse brier.

The yam family is a medium-size tropical and subtropical group with 8 genera and about 630 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 family's representative genus. Sweet potatoes are called yams in the southern United States but are unrelated to true yams (see Morning Glory).

Scientific classification: Lily is the common name for the family Liliaceae, of the order Liliales. The onion genus is Allium. Onions and shallots are produced from the species classified as Allium cepa. Garlic is classified as Allium sativum, chives as Allium schoenoprasum, and leeks as Allium porrum. Asparagus is classified as Asparagus officinalis and asparagus fern as Asparagus setaceus. The aloe genus is Aloe. The water hyacinth belongs to the family Pontederiaceae and is classified as Eichhornia crassipes. Sisal hemp, from the species classified as Agave sisalana; true hemp, from the species classified as Cannabis sativa; the Joshua tree, classified as Yucca brevifolia; and the century plant, classified as Agave americana; all belong to the family Agavaceae. The carrion flower, classified as Smilax herbacea, and the greenbrier, classified as Smilax rotundifolia, belong to the family Smilacaceae. The sweet potato belongs to the family Convolvulaceae and is classified as Ipomoea batatas.