Many gardeners encounter a common plant often mistaken for the traditional four-leaf clover, only to discover it is a persistent weed. This plant, frequently appearing in lawns and garden beds, can cause confusion due to its similar leaf structure. This guide clarifies the plant’s nature and provides strategies for effective control.
What is “Four Leaf Clover Weed”?
The plant commonly referred to as “four-leaf clover weed” actually belongs to the Oxalis genus, most frequently Oxalis corniculata (creeping woodsorrel) or Oxalis stricta (yellow woodsorrel). These plants are also known by various common names such as sourgrass, false shamrock, or lemon clover, reflecting their slightly tart taste when consumed. Oxalis species typically feature leaves composed of three heart-shaped leaflets, which can range in color from green to purple.
Small, five-petaled flowers, usually yellow, emerge from spring through summer, followed by distinctive cylindrical seed pods. Oxalis corniculata often grows low to the ground with creeping stems that can root at the nodes, while Oxalis stricta tends to have a more upright, clumping growth habit. These plants can reach heights of about 4 to 12 inches and are often found in disturbed areas, including lawns, gardens, and even sidewalk cracks.
Distinguishing It from True Clovers
While Oxalis species are frequently confused with true clovers (Trifolium species), key differences aid identification. The most apparent distinction lies in the shape of their leaflets: Oxalis has distinctly heart-shaped leaflets, whereas true clovers have more rounded or oval-shaped leaflets. Additionally, true clover leaves often display a faint white V-shaped marking, which is absent in Oxalis.
Their flowers also differ significantly. Oxalis species typically produce small, individual yellow flowers with five petals. In contrast, true clovers, such as white clover (Trifolium repens), produce dense, globular clusters of small white, pink, or red flowers. The “lucky” four-leaf clover is a rare genetic mutation of true clover, not Oxalis, even though Oxalis can sometimes produce four leaflets.
Is it a Nuisance?
Oxalis species are considered weeds by gardeners due to their aggressive growth and prolific reproductive strategies. They spread rapidly through multiple mechanisms, making them challenging to control. They produce copious amounts of seeds within small, okra-shaped capsules that explosively dehisce when mature, flinging seeds up to 13 feet away. This ballistic dispersal contributes to their widespread presence.
Beyond seeds, many Oxalis species also spread vegetatively. Oxalis corniculata, for instance, forms creeping stems that root at the nodes, establishing new plants as they spread across the ground. Some species also produce underground rhizomes or tiny bulblets, which can easily detach and sprout new plants, especially when the soil is disturbed. Their ability to thrive in various conditions, from full sun to partial shade and in both moist and dry soils, allows them to quickly outcompete desirable garden plants for resources.
Controlling “Four Leaf Clover Weed”
Effective control of Oxalis involves a combination of methods. For small infestations, manual removal is an option; however, extract the entire root system, including any bulblets or rhizomes, as fragments can regrow. This task is often easiest when the soil is moist. Preventing plants from flowering and setting seed is important to prevent seed production.
Cultural practices help suppress Oxalis. Applying a 2-3 inch layer of mulch in garden beds reduces seed germination, as Oxalis seeds require light to sprout. Maintaining a dense, healthy lawn through proper fertilization and mowing heights creates an environment where Oxalis struggles to establish. Ensuring good soil drainage discourages its spread.
For larger infestations, chemical control may be necessary. Pre-emergent herbicides, applied before seeds germinate, prevent new Oxalis from emerging, though timing is important for effectiveness. Post-emergent herbicides, applied to actively growing plants, are also used. Selective broadleaf herbicides target Oxalis without harming most lawn grasses. Non-selective options containing glyphosate can be used for spot treatments in landscape beds, taking care to avoid desirable plants. Always read and follow product label instructions carefully for safe and effective application.