The best way to identify a plant is to describe its parts and compare your description to authoritative references. Since there are thousands of plant types growing in the United States, selecting a reference specifically for your area’s plants makes correct identification easier. Authors usually group plant guides by major categories, such as trees, shrubs, wildflowers, herbs or flowers. Knowing the larger category helps you refine a reference search and identify the plant more quickly. Applying common descriptors for plant’s flowers and leaves facilitates identifying the plant in your reference materials.
Flowers provide clues to help identify a plant, including its color, size and distribution of flower petals. Added information to help use flowers to identify a plant is the flower shape, whether it is round with petals evenly distributed, tubular or lopsided. For example, daisies have a regular or even distribution of petals around a center, while irises are lopsided, with the petals on one side longer than those on the opposite side. Salvias and honeysuckle plants have tubular-shaped flowers.
Other useful information to identify a flowering plant includes the width of the flower, the height of the plant and how many flowers occur on each stem. The time of year that the flower is in bloom and whether it is growing in sun, partial sun or complete shade helps refine the search for the plant’s identity. For example, using the Wildflower Center’s plant database, you would describe Louisiana phlox as 1 to 3 feet tall, with pink flowers, blooming in spring in shady areas. Giving the geographic location helps narrow the search to most likely candidates for correct identification. Once you have narrowed your identification search to a few likely candidate plants, reference books and on-line sources provide pictures and complete descriptions you can use for comparison.
With or without flowers, the leaves of a plant can help you identify it considering the shape or form of the leaf blade and describing its edges. Common leaf shapes are deltoid or triangular, elliptical, lance shaped, oval, and heart-shaped – called chordate. Triangular leaves with lobes at the bottom are called hastate leaves. For example, a cottonwood tree’s leaves are classified as triangular because the edges are smooth and even, while a caladium leaf, although generally triangular in shape, has lobes at the bottom of the leaf classifying it as hastate-shaped.
Leaf edges or margins look smooth, sinuate with small curves, dentate or serrated with sharp points or lobed, with severe indentations that go almost to the mid-point of the leaf. For example, maple and oak trees have lobed leaves, while elm tree leaves are serrated and the leaves of witch hazel trees are sinuate. Trees with needle-like leaves, such as pines, are placed in a separate category for classification using needle length, clustering and bark texture to assist in making the correct identification.