These three families, Poaceæ, Liliaceæ, and Orchidaceæ, are perhaps the most important of all the monocotyledons, although commercially the palms, or Palmaceæ, are extensively used. It is impossible to describe or even mention all the monocotyledonous families, but a list of the more important is added. The families are arranged in the order that seems to reflect the development from simpler ones to the most complex, and is the sequence of such families used by nearly all botanists in describing the plant families of the world:
Typhaceæ—The cat-tails. Tall, reedlike swamp plants found throughout the world. One genus and about ten species.
Pandanaceæ—The screw pines. Shrubs or trees with stout, woody trunks and mostly prickly margined, long sword-shaped leaves. Confined to the Old World tropics.
Poaceæ—The grasses. Noted above.
Cyperaceæ—The sedges. Grasslike plants with solid, often triangular stems. Very often inhabitants of wet places. Throughout the world, Crex rugs are made from a species of Carex, the largest genus in the family. About 75 genera and 3,200 species.
Palmaceæ—The palms. All trees or shrubs, or sometimes climbing vines. Includes the coconut and palm-oil trees, two palms of tremendous economic importance. Inhabitants of tropical and warm regions, and only very few found in the United States. Over 130 genera and 1,200 species.
Araceæ—The arums, of which the jack-in-the-pulpit is our best-known native representative. They are nearly always herbs, often of giant size, and the great majority are found in the tropical regions. Flowers very minute, crowded together on a central column (the spadix), and this often surrounded or having at its base a leaflike appendage (the spathe). Calamus root and the skunk cabbage are also native representatives. About 105 genera and over 900 species.
Liliaceæ—The lily and related plants, noted above.
Smilaceæ—Smilax. Mostly prickly vines; our native kinds often called cat briers. Sarsaparilla comes from at least four species of Smilax. Three genera and about 300 species, mostly natives of tropical, but a few of temperate regions.
Amaryllidaceæ—The amaryllis family, noted chiefly for the sisal fiber that comes from a species of Agave, which is one of the many different kinds of century plant. The family has usually capsular fruits and black seeds, and the narcissus and amaryllis of our gardens are well-known members. About 70 genera and 800 species from tropical and warm countries; a few in temperate regions, mostly herbs.