Tall Fescue (Festuca arundinacea) is a resilient, deep-rooted cool-season grass often used in turf or forage settings due to its durability and tolerance to heat and drought. When it appears unexpectedly in a fine-textured lawn, its coarse texture and distinct growth habit make it stand out as a problematic weed. Accurate identification requires observing several unique physical characteristics.
Visual Indicators: Color and Growth Pattern
The first indication of Tall Fescue is its distinctly bunch-type growth habit. Unlike grasses that spread laterally through rhizomes or stolons, Tall Fescue grows vertically, forming dense, isolated clumps. This clumping pattern makes individual plants highly noticeable against a backdrop of uniformly spreading turfgrass.
The overall texture is coarse and rough compared to finer grasses like Kentucky Bluegrass or Creeping Red Fescue. Tall Fescue is often a deep, dark green, sometimes appearing almost blue-green, which contrasts sharply with lighter lawn varieties. This combination of non-spreading, clumping growth and deeper color saturation causes the clumps to appear as distinct, darker patches scattered throughout the lawn.
Detailed Examination of the Leaf Blade
The dimensions of the Tall Fescue leaf blade provide further confirmation. This grass is characterized by significantly wide blades, typically measuring between one-quarter and one-half inch across. This width is noticeably greater than the narrow blades found on most cultivated turfgrasses, contributing to the overall coarse texture of the plant.
The surface texture of the leaf blade is another distinguishing feature, particularly on the upper side. Numerous pronounced ridges or ribs run parallel along the length of the blade. These prominent veins give the top surface a rough, almost corrugated feel when rubbed lightly.
A distinct central vein, known as the midrib, runs down the entire length of the leaf. This midrib is often slightly lighter in color and appears raised or keeled on the underside of the blade. The combination of the wide blade, prominent veins, and the defined midrib offers strong evidence for identification.
Definitive Markers: Ligules and Auricles
The most definitive confirmation of Tall Fescue requires examining the collar region, which is the junction where the leaf blade meets the leaf sheath surrounding the stem. To view these small structures clearly, one must gently peel back the leaf blade from the stem. This close inspection reveals two structures: the ligule and the auricles.
The auricles are the most reliable identifier for Tall Fescue, as they are large, claw-like appendages that extend horizontally from the collar. These structures are prominent and distinctly wrap around or “clasp” the stem, often overlapping each other. The presence of these large, clasping auricles is a primary feature that separates Tall Fescue from many other common lawn grasses.
Just above the auricles is the ligule, which is a small, membranous structure that acts as a barrier between the leaf blade and the stem to prevent water and debris from entering the sheath. In Tall Fescue, the ligule is very short and typically appears as a blunt, collar-like membrane. It does not have the appearance of a fringe of hairs. The combination of the substantial, clasping auricles paired with the short, blunt ligule provides confirmation of the grass specimen’s identity.
Common Confusion: Separating Tall Fescue from Other Grasses
Tall Fescue is often confused with other common lawn types, most frequently Kentucky Bluegrass and Perennial Ryegrass, making comparative analysis necessary. The primary difference lies in the growth pattern, as Kentucky Bluegrass spreads aggressively via underground stems called rhizomes, creating a dense, uniform sod. Tall Fescue, conversely, maintains its clumping, bunch-type habit without any rhizomatous spread.
Differentiating Tall Fescue from Perennial Ryegrass is slightly more challenging, as Ryegrass also exhibits a bunch-type growth habit and a similar coarse texture. However, the definitive auricles provide the distinction; while Perennial Ryegrass does have small, non-clasping auricles, they are significantly less pronounced and smaller than the large, overlapping auricles of Tall Fescue.
The leaf tip also offers a subtle clue, as Kentucky Bluegrass has a distinctly boat-shaped or pointed tip, whereas Tall Fescue and Perennial Ryegrass usually have sharp, pointed tips. Furthermore, Kentucky Bluegrass lacks auricles entirely, relying only on a short ligule for identification at the collar. By systematically checking the growth habit, leaf width, and the presence of large, clasping auricles, one can reliably separate Tall Fescue from its common look-alikes.