This all too brief account of the grouping of plants in families, and the sequence of these from the comparatively simple naked-seeded pines, through monocotyledons, the apetalous dicotyledons, followed by the polypetalous dicotyledons, and culminating in the Compositæ among the gamopetalous families, gives us merely a hint of what are the characters upon which plants are divided. While the details are necessarily omitted, the gradual development from naked-seeded plants, wholly at the mercy of the elements, up to those which are marvelously provided with contrivances to insure cross-fertilization, has been traced. Perhaps no other phase of botanical study offers such a rich opportunity as this, for upon the solution of some of the problems of plant classification depends the answer to many questions about the history of the earth and man’s ability to live on it. Certain of these plant families have lived on the earth hundreds of thousands of years before man first came. Others have apparently arisen comparatively recently. Many botanists believe that all the monocotyledons should be placed after the dicotyledons, as the latter may be a more ancient type than the former. How these different plant structures, some very ancient and others more recent, help to show us some of the history of the earth, will be treated, among many other evidences of a plant nature, in the chapter on “The History of the Plant Kingdom.” CHAPTER V USES OF PLANTS TO MAN For perhaps the largest number of readers the chief value of plants is what they furnish in the way of food, clothing, fuel, and so forth, and from this standpoint alone the study of them is more than worth while. It is unnecessary here to enumerate all the thousand and one things that we get from plants, and no attempt will be made to do so in the following pages. But certain plants like wheat, corn, cotton, jute, rubber producers, and tobacco have so shaped the life of the people, so absolutely dictated the development of whole regions of the earth’s surface that their stories are part of the history of mankind. What our cotton fields of the South, the wheat and corn fields of the Middle West, the jute in India, and the coconut palm and sugar cane in the tropics have done to dictate the economic destiny of those regions is common knowledge. Hundreds of less important plants throughout the world contribute their quota to the huge debt that man owes to the plant world. Probably no other feature of plant life offers such attractions as the study of man’s uses of plants, which is known as Economic Botany, and for which our Government maintains a large staff of experts. Some of the publications of this bureau are textbooks of the greatest value to those who grow or import plants or their products. What that amounts to in the aggregate no one can readily estimate. It certainly exceeds all other commerce combined. 1. FOODS