The leaves of oxalis, also called creeping woodsorrel, have a shamrock appearance and the plant is often mistaken for a clover. At night, or on cloudy days, the leaves may fold up. With the arrival of cooler weather in the fall, leaves turn purplish in color. Occasionally, some plants may have purple leaves all year round. Oxalis is a prostrate, creeping perennial weed with stems that will take root where they touch the ground. Flowers are small and yellow. When mature, fruits explode, scattering seed several feet away. Oxalis blossoms This plant is more common in thin, less vigorous turfgrass that is given too-frequent, light irrigation. It can be discouraged by increasing the density of turfgrass using good cultural practices. See CSU Fact Sheet 7.202. Control 2,4-D combination herbicides applied in spring and/or fall give marginal levels of control. Triclopyr + clopyralid control is fair to good. Pre-emergent herbicides (pendimethalin, dithiopyr, isoxaben, prodiamine) applied 2-3 successive years in late March - early April can provide some control.
Photographs courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010