Yellow Woodsorrel

Yellow Woodsorrel is a delicate-looking but persistent broadleaf weed that thrives in lawns, gardens, and landscape beds. Despite its clover-like appearance, it is not a true clover—it belongs to the Oxalis family. This weed can reproduce rapidly by both seed and creeping underground stems, allowing it to form colonies that invade thin or stressed turf. Its small yellow flowers and heart-shaped leaves often make it deceptively attractive, but it can quickly overtake lawns if left unmanaged.

How to Identify

Yellow Woodsorrel is identified by its trifoliate (three-part) leaves that resemble clover, though each leaflet is distinctly heart-shaped and often folds downward at night or during hot, sunny conditions. The leaves are light green and grow alternately along slender, branching stems. It produces small, bright yellow flowers with five petals, which develop into upright, cylindrical seed pods that explosively release seeds when mature. When crushed, the plant has a tangy or sour taste, which is why it’s sometimes called “sourgrass.”

Lifecycle

Yellow Woodsorrel is a perennial in warm climates and can behave as a summer annual in cooler regions. It grows actively from spring through fall and spreads by seeds, rhizomes, and creeping stems. Seeds can germinate throughout much of the growing season and are capable of shooting several feet away from the parent plant, ensuring continuous reestablishment.

Prevention & Control

Effective control involves both cultural and chemical strategies. Hand-pulling can work on small patches if roots are completely removed. Pre-emergent herbicides may reduce seed germination, while selective post-emergent herbicides labeled for Oxalis control are effective on actively growing plants. Keeping turfgrass thick and healthy through proper fertilization, mowing, and irrigation will limit new seedling establishment. Mulching in beds can also help prevent germination in ornamental areas.