Being able to correctly identify different plants is useful in giving them the proper care. Because leaves are visible, plant foliage is the basis for identifying a particular plant. First, become familiar with the leaf characteristics of various plants. A leaf’s form, size, shape and color are key clues in determining the identity of a plant, notes Oregon State University. Even a leaf’s odor, especially when crushed, can offer information in identifying a plant.
A leaf has three parts: the blade, the petiole and the stipule. The blade, the most obvious part, is the wide, flat portion of a leaf. The petiole is the stalk supporting the blade and is attached to the blade. The stipule is at the bottom of the petiole and is attached to the stem, notes the Bridgewater Education website.
Leaves come in various shapes. Linear-shaped leaves are narrow and much longer than they are wide. Elliptical-shaped leaves, which are two to three times longer than they are wide, taper to a rounded or acute apex and base, notes the University of Arizona. Ovate or egg-shaped leaves have a wide basal portion that tapers towards the apex. Lanceolate leaves, which are longer than they are wide, taper toward the apex and base. Heart-shaped or cordate leaves are broadly ovate and taper to an acute apex. Their base turns in and forms a notch at the spot where the petiole is attached.
Determining a leaf type is important in identifying a plant. Leaf types are either simple or compound. While simple leaves have only one blade, compound leaves have multiple leaflets. There are several varieties of compound leaves, says Oregon State University. Palmately compound leaves consist of three or more leaflets that are attached to the end of the stalk, while pinnately compound leaves have many leaflets attached on a central stalk.
How leaves are arranged on a stem is an important factor in identifying plants. A rosulate arrangement is where the basal leaves create a rosette around a stem with exceptionally short nodes. An opposite leaf arrangement has leaves positioned across the stem, opposite from each other, with two leaves found on each node. Alternate (spiral) leaf arrangements are positioned in alternate steps on a stem, having a single leaf at each node. Whorled leaves are formed in circles along a stem.
Considerations and Warning
Besides leaf arrangements, other considerations should be noted. Consider whether the leaf margins are smooth, toothed or doubly-toothed, notes Mountain Nature.com. Notice whether the leaf is round or linear-shaped. Discern if the veins run outward from a center vein or if they run parallel to the leaf margin. Determine if leaves are smooth or hairy.
Some differences in plant foliage are subtle, cautions Rutgers University. It helps to compare the leaves of a plant with the foliage of other plants growing around it, noting how it differs.