Carpet grass is a warm-season perennial known for its use as a low-maintenance turf or pasture grass in the southern United States and tropical regions. It forms a dense, low-growing cover, often valued for its ability to thrive where other grasses fail. Identifying this grass accurately requires close inspection of its specific physical features, including its leaves, growth habit, and reproductive structures.
General Characteristics and Habitat
Carpet grass is scientifically known as Axonopus fissifolius or Axonopus affinis. This native, warm-season grass is typically low-growing, reaching heights of 8 to 20 inches when unmowed and forming a thick, uniform cover. It is well-suited for low-maintenance areas like parks and roadsides because it tolerates a wide range of poor conditions.
It prefers acidic and moist soils, often thriving in areas too wet for grasses like Bermuda grass, and can also tolerate moderate shade. While it performs well in low-fertility soils, it becomes chlorotic or yellowed in alkaline soils with a pH above 7.
The Distinctive Leaf Blades
The leaves of carpet grass are a noticeable light-to-medium green, often described as apple or yellowish-green, which distinguishes it from darker turf grasses. The blades are relatively wide, typically ranging from 0.16 to 0.31 inches (4 to 8 mm) across. They are usually flat or folded along the midrib and emerge from the stem in a folded fashion.
A defining characteristic is the shape of the leaf tip, which is often blunt, rounded, or boat-shaped, unlike the sharper points of some other grasses. The blades are generally smooth, though fine hairs may be present along the margins near the base. These wide blades contribute to its overall coarse texture compared to fine-bladed grasses.
Growth Pattern and Texture
Carpet grass spreads aggressively using above-ground runners called stolons, which root at the nodes to form new plants. These stolons are flat and widely branched, creating a dense, low-lying, mat-like growth habit that gives the grass its name.
The resulting texture of a carpet grass lawn is often described as coarse or spongy underfoot due to the thick mat of stolons and leaves. The plant sends up distinct, vertical stalks for reproduction. This contrast between the low mat of leaves and the upright reproductive structures is a key visual feature during the growing season.
Identifying Seed Heads
The seed head is the most definitive feature for identifying carpet grass, as it is produced frequently and prolifically. These reproductive structures consist of two to five slender spikes, or racemes, that extend upward on a tall, thin stalk. They are typically arranged in a distinctive pattern that resembles a “turkey foot” or a small, three-pronged structure.
In the most common arrangement, two spikes form a V-shape at the top of the stalk, with a third spike often extending from just below that junction. The racemes themselves are 1.5 to 4 inches long and bear small, paired spikelets alternately along their length. The frequent appearance of these tall stalks above the mowed turf makes the seed head the easiest way to confirm the presence of carpet grass.