Common Oxalis

Oxalis is an aggressive species that responds best to manual control.

The bright-yellow flowers and soft-green foliage of common yellow oxalis adds a shade of tranquility to any space. Oxalis stricta, or yellow woodsorrel, is found throughout North America from British Columbia to Florida. Often considered an invasive weed, this species is identifiable by its narrow, yellow-green stems and its rounded leaves. The leaves of this species of oxalis grow in clusters of three and have an appearance similar to clover.

Characteristics

Common yellow oxalis produces bright-yellow flowers with five petals in a tight cluster near the top of the plant. Prior to opening, the flowers resemble a small, yellow vase. Underneath its flowers, common oxalis sports rounded clusters of bright-green leaves with a rim of slender, white fur. Its flowers, leaves and fruit are supported by slender stalks that range between pale green and light pink. The fruit of common oxalis is typified by narrow ridges and an elongated form that terminates in a point.

Growth

Oxalis stricta is a perennial plant that grows in a variety of locations across North America. It spreads through seeds and rhizomes, giving gardeners several choices when introducing this plant. Common oxalis develops deep taproots that are often difficult to remove from containers, making transplanting difficult with well-established plants. The primary method for spreading common oxalis is through its seeds. The seed pods of common oxalis contain a dispersal mechanism that causes its seed pods to open at the slightest touch once the pod has dried. Upon opening, its seeds are carried for several feet by the wind. However, common oxalis can also spread using its root system, allowing it to spread colonially.

Requirements

Common oxalis is a very adaptable plant that grows year-round in warm climates but acts as an annual in cooler regions. It can thrive in soils that are poor or rich in nutrients, but it prefers relatively moist soil. In spite of this preference, common oxalis is capable of growing in environments that sustain periods of drought as well. Oxalis typically grows in grasslands, woodlands and disturbed sites and does well in both direct sunlight or shade.

Control

Although it is commonly found in gardens, common oxalis is considered an invasive species of weed in many places. The most effective method of controlling common oxalis is hand removal. Since it can regrow from its roots, mechanical removal through tilling or mulching will not kill the plant. Most types of herbicide are largely ineffective against common oxalis, requiring multiple treatments to kill the plant. Herbicidal treatments are generally more effective if they are used early in the plant's development cycle. Burning is also an ineffective method of treatment due to the species' ability to regrow from its roots.

References

• United States Geological Survey: Fact Sheet for Oxalis Stricta L.; William L Halvorson, et al; 2003
• Electronic Atlas of the Plants of British Columbia: Oxalis stricta L.; Ed. Brian Klinkenberg; 2010
• USDA Plants Database: Oxalis stricta L. - common yellow oxalis