Plants exhibit an enormous range of shape and form. Common shapes include the conical form of conifers, the vase shape of many shrubs, the linearity of scrambling vines, and the clumped form of a daylily. Ferns have a range of forms nearly as great as flowering plants, while mosses usually take the form of miniature herbs. These plant forms result from enhanced growth in one region occurring at the expense of growth in another area. Shape results from differential growth, localized cell division, and cell expansion.

New plant cells come from single embryonic cells or groups of embryonic cells called meristems. Two groups of embryonic cells are responsible for the origin of all new shoot parts in seed plants: the shoot apical meristems and the lateral meristems. Shoot apical meristems, also called primary meristems or growing points, are found at...