Weeds can be a nuisance in fields or gardens, but they aren’t inherently bad. Many help stabilize the soil, provide food for animals and humans, and add organic matter to the earth. But some can be invasive, displace native plants, and even alter the ecosystem. For example, field bindweed and purple loosestrife are both noxious weeds in the United States.
If you want to identify a weed down to the species level, start with a dichotomous key, which is a series of “either-or” pairs of plant characteristics that narrow down the possibilities until you find the correct name for the weed. A good weed identification guide has photos and detailed descriptions that can be used to confirm the plant’s identity.
Another tool is an app called PlantSnap, which allows users to use their smartphone or tablet’s camera to identify plants and flowers. This is available free of charge, though there are in-app purchases to unlock more advanced features.
A final method for weed identification is to bring the plant to a county Extension office or a university weed science department for assistance. Be sure to bring specimens from a variety of seasons and growth stages, because some weeds look similar at different times of the year or under different conditions. And don’t forget to bring the common names for the weed; a single plant might be known by multiple names, such as lambsquarters and fat-hen, or witchgrass and redroot pigweed.