Quackgrass (Elymus repens) is an invasive, cool-season perennial grass often mistaken for desirable turf or other common weeds. This aggressive plant is a widespread problem in lawns, gardens, and agricultural fields due to its tenacious growth habit. Proper identification is necessary for effective control, as this weed requires different management strategies than annual grasses.
General Appearance and Growth Habit
Quackgrass is an erect, coarse-textured grass that typically stands out from finer turfgrasses because of its broader leaf blades and distinct color. If left unmowed in a field or garden, the plant can reach heights of up to four feet, though in a maintained lawn it will be significantly shorter. Its foliage often displays a grayish-green or light blue-green hue, making the individual shoots noticeable against the backdrop of a darker green lawn.
The plant forms dense, spreading patches rather than isolated clumps, quickly colonizing an area. This patch-forming habit results from its underground structure. Shoots emerge individually from the soil, giving the patch a uniform, thick appearance compared to the bunched growth of other grasses.
Detailed Leaf and Stem Characteristics
The most reliable way to identify Quackgrass is by examining the collar region, which is the junction where the leaf blade meets the stem. A defining feature is the presence of prominent, slender auricles, which are small, claw-like appendages that wrap around and visibly clasp the stem. These auricles are often whitish-green to reddish and serve as an important distinguishing mark from many other common lawn grasses.
The leaf blades are typically flat, sometimes displaying a slight longitudinal twist, and can grow between 6 and 16 inches long with a width up to 0.4 inches. The edges may feel rough, and the upper surface can be sparsely hairy or smooth. Just above the clasping auricles is the ligule, a very short, membranous structure often less than 0.04 inches long, making it inconspicuous. The leaf sheaths, which enclose the stem, are generally smooth, though the lowest sheaths may sometimes have fine hairs.
The Underground Network: Rhizomes
The aggressive nature of Quackgrass is due to its extensive system of underground stems, known as rhizomes. These rhizomes are slender, tough, and typically appear pale yellow to whitish, often described as straw-colored. They function as a powerful means of vegetative reproduction, allowing the plant to spread rapidly and form large, interconnected patches.
These horizontal stems have sharply pointed tips, allowing them to penetrate compacted soil and the roots of neighboring plants. The rhizomes spread aggressively, sometimes reaching lengths of up to 11 feet, with the majority found within the top six inches of the soil profile. New shoots and fibrous roots develop from the nodes, or joints, along the length of the rhizome. Disturbing the plant, such as by tilling, can fragment the rhizomes, with each small segment potentially sprouting into a new, independent plant.
Look-Alikes: Avoiding Misidentification
Quackgrass is frequently misidentified, most commonly confused with other grassy weeds like Crabgrass or Tall Fescue. Differentiating Quackgrass from these look-alikes centers on two factors: the presence of rhizomes and the structure of the leaf collar. Unlike Quackgrass, Crabgrass is an annual weed that spreads by seed and has a shallow, fibrous root system without rhizomes.
Crabgrass also lacks the distinctive, clasping auricles characteristic of Quackgrass, and it exhibits a more horizontal, mat-forming growth habit close to the ground. Tall Fescue is a perennial, cool-season grass that is a bunch-type and does not produce spreading rhizomes. While Tall Fescue has auricles, they are much shorter and blunter, never fully wrapping around the stem like those on Quackgrass.