Iridaceæ—The iris, the source of orris root, and containing some our most beautiful garden plants, the blue-eyed grass of fields, and over 50 genera and 100 species are found in this family. Nearly throughout the world, and nearly all herbs.
Musaceæ—The banana and traveler’s-tree. Giant herbs, in the banana having the largest leaves known, frequently twelve feet long and two wide. Natives of tropical and warm regions, and 4 genera and 75 species are known. Flowers often very irregular, and in Strelitzia gorgeous.
Orchidaceæ—The orchids, already noted.
While there are many thousands of plants contained in these monocotyledonous families and in the others not mentioned here, they make up only about one-third of the total number of different kinds of plants known in the world. But in grasses and sedges, in the rushes and a few other families, the number of individuals is greater than in probably any other plant family.
Dicotyledonous Plant Families
All the great bulk of the flowering plants not included in the monocotyledons or the gymnosperms belong to about two hundred plant families that are included in the dicotyledons. In all of them the seed sends up two seed leaves, there are generally netted-veined leaves and the parts of the flower are in fours or fives or multiples of these numbers. In such a large aggregation of plant families there are three well-marked divisions, namely, those that bear no petals or sepals, those that do bear them and where they are separated to form individual sepals or petals, and those where the petals are united to form some sort of a tubular or at least connected corolla. These divisions are perhaps best shown thus:
(a) Apetalæ—Including families where the petals are never present, and in some there is even no calyx. Examples: walnut, hickory, willow, and oaks.
(b) Polypetalæ—Petals present but separate, not forming a tubular or connected corolla. Examples: buttercup, rose, pea, apple, geranium.
(c) Gamopetalæ—Petals united and forming some sort of a tubular or connected corolla. Examples: garden primrose, gentian, salvia, mint, snapdragon, and the daisy family.
Any attempt to describe the families contained in these three divisions of the dicotyledons would take all the rest of this book and crowd out other things about plant life that must not be omitted. All that can be done here is to outline briefly a few families in each division so that we shall have fixed in our minds what the general principles of plant classification are and how these are illustrated by well-known plants. There are many books that deal with this subject in great detail and to them the student should go for further elaboration of the subject. It is one of the most interesting phases of the study of botany, but it demands a longer and more intensive study than can be included here.