Botanic Gardens Conservation International, which seeks to prevent plant extinction and promote sustainable ecological practices, estimates there are about 400,000 known plant species throughout the world. Many more have yet to be found, let alone named, which means even the experts can be stumped when it comes to identifying a plant. But amateurs need not be discouraged by the initially intimidating process. Technological advances have made it easier and quicker to narrow search parameters, and cross checks with field guides can provide more certainty. Basic observations will start the process.
A plant's structure offers obvious clues as to its identity. Look at its overall color, shape and size. Observe what its leaves look like and how they are placed in relation to each other. See if the plant has flowers and fruit, and note what those look like. Note potential protective measures, like prickly seed coats.
Observe growth patterns. Most plants, for instance, begin as seedlings with a few leaves but later sprout flowers and grow bean pods as they mature. Deciduous trees have leaves that change color from spring to fall, and then fall off. Does the plant grow like a tree, vine, groundcover or moss? Knowing how a plant changes and behaves during its life cycle and when seasons change will help tremendously with identification.
Flowers and fruit offer excellent identification clues. Note if the plant flowers and what time of the year that happens. Observe the color, shape and size of the flowers, how they are clustered, what they smell like and what kind of insects or mammals pollinate them. Take note of how big it is, the color, what types of animals rely on it as a food source and whether the plant has fruit that is clearly visible.
Pay attention to the plant's relationship with other plants and animals. See if it grows close to other plants that appear to be of the same kind. Determine whether other plants seem to be helping it survive by providing shelter from the wind and sun. Do certain animals avoid eating or coming into contact with it?
Several websites hosted by reputable educational, scientific and government groups offer plant identification keys, providing scientific and common names. Those help narrow a search by asking specific questions about a plant's physical appearance and growth habits. There are also many field guides that help with searches. Each offers detailed pictures for comparison and contrast.