Nymphæaceæ—The water lilies. Aquatic plants with usually large showy flowers in which the calyx, corolla, and stamens often merge one into the other so that it is sometimes difficult to know where one series ends and the other begins. Five genera and 45 species throughout the world.
Ranunculaceæ—Buttercup family. Includes buttercups, clematis, columbine, meadow rue, golden seal, marsh-marigold, hepatica, and scores of other native plants. All herbs, except a few semiwoody vines like clematis. Sepals always present, and where no petals are found, as in marsh-marigold, colored like them. Highly irregular flowers are not uncommon, as in columbine and monkshood. The fruits are berrylike in some genera and in others dry capsules. Thirty-five genera and over 1,000 species throughout the world, but most abundant in temperate regions.
Lauraceæ—Laurel or sassafras family. Includes besides them the guava and cinnamon and camphor trees, all tropical, and the native spice-bush. All trees and shrubs with small, yellow, or greenish-yellow flowers and usually aromatic juice. Fruit a one-seeded drupe or a berry. About 40 genera and over 1,000 species, nearly all tropical, but a few in the United States.
At this point, in the sequence of plant families, there are two or three families that bear quite different fruits than any heretofore noted, and in one of them, at any rate, the four petals are in the form of a cross. So uniformly is this true that the family was for years known as the Cruciferæ, but is better known as Brassicaceæ, from Brassica, the generic name of the mustard. This large mustard family mostly has fruits known as a silique or silicle, which are pods that split into two valves; and yellow or white, rarely pinkish flowers. The juice is always somewhat acrid, familiar through the pleasant pungent taste of water-cress, but none of the family is poisonous. There are over 200 genera and nearly 2,000 species of wide distribution, and common representatives include the cress, mustard, horse-radish, garden stock, sweet alyssum, cabbage, cauliflower, brussels sprouts, radish, and turnip.
Between the Brassicaceæ and the following families there are many others that cannot be mentioned here. Somewhat farther along in the sequence are a group of families, large and important, and all having their stamens inserted around or even above the ovary, and in which the sepals are partly or wholly united. They include some of our most beautiful flowers and useful fruits. Of the many closely related families that agree in these characters the two most important are:
Rosaceæ—Rose family. In the broad sense including, besides the rose, the strawberry, blackberry, apple, pear, peach, plum, besides many herbs with wholly dry fruits. There are always five petals, five lobes to the partly united calyx, but numerous stamens. They may be herbs, shrubs, or trees, with simple or compound leaves, but these are nearly always alternately arranged. There are over 100 genera and nearly 2,000 species. Because of the size of the Rosaceæ and differences in fruit, the apple and its relatives are often included in a separate family, the Malaceæ ([Figure 96]), and the peaches and plums in Amygdalaceæ. The general structure of the flower is sufficiently uniform, however, for them all to have been included in Rosaceæ ([Figure 97]).
