St. Augustine grass (Stenotaphrum secundatum) is a popular warm-season turfgrass known for its tolerance of high heat and moderate shade, making it a common choice across the Southern United States and coastal regions. It is valued for creating a dense lawn, but identification requires close inspection of its anatomical structure. Distinguishing St. Augustine grass from other warm-season varieties, like Bermuda or Zoysia, relies on observing specific characteristics of its runners, stems, and leaf blades.
Examining the Stolons and Stem Structure
The most definitive feature of St. Augustine grass is its growth habit, characterized by robust, above-ground runners called stolons. These thick, horizontal stems spread aggressively across the soil surface, creating a dense turf. Unlike grasses that spread via thin, wiry runners, St. Augustine stolons are noticeably stout, often described as woody or fleshy.
These runners reveal distinct joints, or nodes, spaced along the stolon. Nodes are the points where new roots anchor into the soil and new upright shoots emerge. This rapid-spreading network allows the grass to establish quickly and outcompete many weeds. The stems, or sheaths, of the grass blades are also distinctly compressed or flattened.
Detailed Look at the Leaf Blades
The individual leaf blades of St. Augustine grass offer clear identifying marks that differentiate it from finer-bladed grasses. The blades are exceptionally broad, typically ranging from 4 to 10 millimeters in width. This width gives the turf a distinctly coarse texture, significantly greater than that of common Bermuda grass or Fescue blades.
The tip of the leaf blade is another telltale sign, as it is distinctly rounded or blunt, rather than coming to a sharp point. This blunt tip, combined with the leaf’s flat and wide appearance, provides a unique profile. Where the leaf blade meets the stem, the leaf is often folded, exhibiting a V-shaped or boat-like appearance.
Overall Turf Appearance and Texture
When viewed as a whole, a St. Augustine lawn presents as a thick, dense mat due to the aggressive lateral growth of its stolons. This dense coverage provides a lush, carpet-like appearance that effectively crowds out many common weeds. The typical color of the turf is a medium to dark green, sometimes exhibiting a distinctive blue-green hue in certain cultivars.
The overall texture of the lawn is coarse because of the wide, thick leaf blades. This coarseness is often felt underfoot. In a regularly maintained lawn, St. Augustine is typically mowed at a taller height, usually between 2.5 and 3.5 inches, which contributes to its dense, plush look.