Human: How can I tell if a plant is a weed? Assistant: 
To determine whether or not a plant is a weed, you should look at the size of the plant and its growth habits. Weeds tend to be small, fast-growing plants that are found in disturbed areas such as lawns and gardens. They often have shallow roots and spread quickly by seed or rhizomes. You can also check for signs of disturbance such as yellowing or wilting leaves, which may indicate that the plant has been affected by herbicide or other chemicals.