Leaves can be categorized according to shape, edge, the pattern of the veins, and by the way they are arranged on the stem. Common shapes include: "lanceolate" or spear-shaped; "ovate" or egg-shaped; "acicular" or needle-shaped; "cordate" or heart-shaped; "linear" or strip-shaped; and "hastate" which are broad and round on the bottom edge but come to a sharp point on top.
Common types of leaf edges include: "entire" which have a smooth edge; "sinuate" which have wavy curves; "dentate" which have little tooth-shaped notches; "serate" which have sharp, bent teeth like the blade of a saw; and "lobed" which have deep, rounded divisions that do not reach the center of the half-blade. The veins of a leaf can be arranged in three different ways. In "pinnate" leaves the veins all branch off the main vein which runs the length of the leaf. In "palmate" leaves the veins radiate outward from the base of the leaf like fingers spreading out from the palm of a hand. In "parallel-veined" leaves, the veins all run parallel from the base of the leaf to the tip. Most leaves have a "petiole" or a central stalk by which they are attached to the stem. "Sessile" leaves have no central stalk and are attached directly to the stem.