Which of the following is a common weed found in turf?

Clover is recognized as a common weed in turf. It typically emerges in lawns and grassy areas where there are low nutrient levels because it can thrive in poor soil conditions. Clover is a legume, which means it has the ability to fix nitrogen in the soil, helping it grow even in less-than-ideal circumstances.

In contrast, the other options, such as petunia, rhododendron, and azalea, are flowering plants or ornamental shrubs not commonly found as weeds in turf settings. Petunia is often grown as a garden or container plant, while rhododendrons and azaleas are part of the shrub family, used primarily for landscaping and not typically intermingling with grass in turf areas. Thus, clover stands out as the most relevant choice when discussing common weeds found in turf.