1646. With the separation of the stock or trunk into root, stalk and leaf, the latter organ attains its perfection; it becomes a reticular leaf—the plants possessing it being called reticular.
1647. The retinerved or reticular leaf is, however, only the result of a modified organization in the stalk, and indicates a ramification or foliiform arrangement of the tracheæ in the stem. The foliiform arrangement of the tracheæ in the stalk is their circular disposition. These plants have woody zones. Through this zone or ring of wood first originates the perfect separation into wood, liber and bark, whereof each formerly occupied the whole stalk or stem.
1648. The stalk is no longer a shaft or scape, but it divides into branches and twigs—ramular plants.
1649. The reticular-veined are ramular leaves, and are no longer therefore spathiform but petiolated—petiolated leaves. It is only at the root that spathose leaves may occur, and this only in the plants of the inferior classes.
1650. With the disappearance of the spathose leaves, and the appearance of the ramules, the nodes and bulbs also disappear.
1651. The blossoms stand no longer upon a radical peduncle or stipes, but upon ramules; in other words, upon a plant, which again stands upon another plant, namely, the stalk.
1652. As all the higher separations of leaves here occur, so also does the flower obtain its higher amount of separation; it becomes quinary—pentaschematose plants. The ovarium passes through all numerical conditions, being 1, 2, 3, 4, 5, and polycarpellar. In like manner all the forms of ovaria and fruits occur in the present class, such as caryopsis, follicle, legumen, siliqua, capsule, nut, plum, berry and apple.
1653. As the seed is a leaf-formation, so must it resemble the reticular leaf. But reticular leaves are not spathes or simple tubes, but ramified or separated ribs. The seed has therefore several leaves, and two indeed for the first time, which are called seed-lobes. These plants are therefore styled Dicotyledones.
DIVISION.
1654. The Dicotyledones are, in the first place, empirically divisible into apetalous, monopetalous and polypetalous, or into plants with calycine, tubular and petalous corollæ.