What type of weed is characterized by small white flowers and square stems?

Ground ivy is characterized by small white flowers and square stems, making it distinct among the options provided. This perennial weed typically grows in moist, shady areas and is known for its creeping growth habit. The square stems are a key identifying feature, as they help distinguish ground ivy from other common weeds.

The small white flowers, which bloom in the spring, are another identifying characteristic. The leaves are circular and have a distinctive scalloped edge. Ground ivy can spread rapidly via its stolons, which can make it a troublesome weed in lawns and gardens, especially in cooler climates where cool-season turf is managed.

Other weeds in the choices have different identifiable traits. For instance, common chickweed does not have square stems and has a different flower structure with more prominent white petals. Knotweed generally features stronger, upright growth and distinctive leaf shapes, while thistle is known for its spiny leaves and purple flowers. Understanding these characteristics is essential for effective weed management in cool-season turfgrass.