(Fig. 143), Bananas, Orchids, Lily, and the Grasses. Among the Dicotyledons are found the Oaks, Elms, the fruit-trees, and the most beautiful flowers. The flower of the different kinds of Dicotyledons offers an interesting ascending series. The flower of the Spurge, or Euphorbia, consists of only a stamen or a pistil, known as Achlamydeous, the flower being called accordingly staminate or pistillate. A slight progress is seen in the flower of the Goose-foot, Fig, Mulberry, Elm, etc., in which, however, the corolla is still undistinguishable from the calyx. Such flowers are called, therefore, Apetalae: the flowers of the Monocotyledons are of this kind. In the Bean, Clover, Violet, Geranium, etc., the corolla and calyx are distinct, but the petals forming the corolla are still more or less separated, hence they are known as Diapetalae; in the Gentian, Elder, Ash, Morning-glory, etc., the petals have united; they are known, therefore as Gamopetalee. How the different orders of the Phanerogamia are related to each other is the last question which yet remains unanswered. The structure and reproductive apparatus of the Cycadee and Coniferee would lead us to suppose that they appeared on the earth before the Monocotyledons or Dicotyledons. This view is confirmed by geological evidence, since the fossil Cycadae and Coniferse are found in great profusion at a much earlier period than that in which the Monocotyledons or Dicotyledons first appeared. The Cycadae and Coniferae are probably the posterity of a common ancestor nearly allied to the Lycopodiaceae. Among the Coniferae there is an order, the Gnetaceae, or the jointed Firs, whose structure links them on to the Monocotyledons and Dicotyledons. Some extinct Conifer, allied to the jointed Fir, was the probable common progenitor of these two orders, of which the Dicotyledons are the most complex, both as regards the structure of the stem and flower.
