Which of the following is a defining feature of grassy weeds?

Grassy weeds are characterized by leaves that are straight and narrow, which is a significant feature that distinguishes them from other types of weeds. This leaf structure is similar to that of desirable grasses, making it important for turf managers to correctly identify them to manage them effectively. The narrow leaf blades help these weeds to take advantage of sunlight while competing with turfgrass, making them particularly effective at establishing themselves in lawns and landscapes.

The other options describe features that are not typically associated with grassy weeds. For example, broader leaves are characteristic of broadleaf weeds rather than grassy ones. Wavy margins are also more commonly found in certain broadleaf plants. Lastly, while many grassy weeds may be green, they are not exclusively so; some may show variations in color depending on environmental conditions or stress factors. Therefore, the straight and narrow leaves are the distinctive feature that accurately defines grassy weeds.