To identify weeds, examine the stem, leaves and any fruits produced by the plant. Some weeds also have thorns or flowers that can be used to identify the plant.
To identify weeds early in the season, examine the leaf shape, stem type and general color and appearance of the plant. The two types of leaves most commonly found on immature weeds are broadleaf and grassy. If the plant is mature, examine the flowers, seeds and fruit of the plant. Flowers may be any color or size, but are generally found during early spring or late summer months. Seeds are typically found in late summer or early autumn, when the plant has reached maturity.
The mature leaves and stems of the plant can be used to identify a specific species. Stems may be smooth, fuzzy, segmented, squared or round, while fruit can vary significantly between species of plants. Leaves can be lobed, linear or rounded. In some cases, a plant may be differentiated from similar or related species by observing overall height of the plant.
When two plants are very similar in appearance, a local botany garden can provide free assistance with identification. If botany gardens aren't available, a plant identification book that focuses on plants native to the region can also be used to identify weeds, particularly if the weeds are very common or have medicinal or culinary uses.