How to Identify Garden Plants & Weeds

Look at the leaves. Poison ivy has three leaves which grow together. The weed often takes on a red hue. Ragweed, which affects allergy-sufferers, has leaves that resemble ferns. Thistle's leaves are prickly with fuzzy, purple seed heads. Plantain comes in two forms---broad-leaved and narrow-leaved varieties. The variety with broad leaves are stocky, compact plants that grow in the shade. The other type has long, lance-shaped leaves that grow from wiry stems. If you have a weed that trails like a vine, it's called speedwell. The leaves have a scalloped edge and grow from short stalks.

Study distinguishing features. Dandelions have familiar yellow blooms that look like fuzzy pom poms. They turn into white seed heads which are carried away by the wind. Another well-known weed, crabgrass, grows flat on the ground and has reddish-colored stems.

Examine the flowers. Some weeds look like an attractive addition to the garden. Queen Anne's lace, for example, has lacy white flower heads that are shaped like umbrellas. Hawkweed resembles a daisy with fuzzy stems. Joe-pye weed has tall stems of rose-colored flowers clusters. They smell like vanilla. Wild chicory, another weed, has bright blue flowers.

Enter plant information into a dichotomous (forking) key that is made for plants. These tools are composed of choices of two contrasting statements called couplets. For example, it will ask if the plant has two leaves or more. When you pick your answer, the key goes to another question with two choices. You can continue until you've narrowed down the identification of the garden plants and weeds. Plant dichotomous keys are usually made for individual plant categories such as trees or grasses. See Resources for examples.

Compare the plant's characteristics to pictures in a plant guide book. Start with the most notable features such as bloom color, to help you narrow down the search immediately. University extensions and organizations including the Lady Bird Johnson Wildflower Center have native plant databases you can use.