Bentgrass belongs to the genus Agrostis, a group of cool-season grasses known for forming exceptionally dense turf. It is most frequently recognized as the species used on golf course putting greens and fairways. Accurate identification relies on distinct visual and anatomical markers that set it apart from other common turfgrasses, whether it is intentionally planted or appears unexpectedly in a residential lawn.
Growth Habit and Overall Appearance
Bentgrass develops into a low-growing, tightly woven mat that gives the turf a characteristic plush and velvety texture. This appearance is due to its fine-bladed foliage and its primary method of lateral expansion. The dominant species, Creeping Bentgrass, spreads aggressively across the soil surface through slender, above-ground stems called stolons.
Stolons root at the nodes as they travel, allowing a single plant to rapidly colonize a wide area, leading to a uniform, carpet-like stand. When maintained at the extremely short heights common on golf greens, the combined density makes the surface remarkably smooth. If allowed to grow taller, however, the fine blades tend to flop over, creating a puffy, shaggy look. The overall color is typically a vibrant green, though it can appear lighter or slightly bluish-green compared to surrounding turf.
Detailed Leaf and Ligule Anatomy
To confirm bentgrass identity, examine the junction between the leaf blade and the stem, known as the collar region. Bentgrass leaves are exceptionally narrow, typically measuring 2 to 5 millimeters wide, and are characterized by being rolled in the bud rather than folded. The leaf blade is flat and features a distinct pointed tip.
The most definitive anatomical trait is the ligule, a small membrane located where the leaf blade meets the sheath. Bentgrass possesses a prominent, membranous ligule that is relatively long, often measuring between 1 and 3 millimeters. This ligule is typically pointed, or sometimes finely irregular-toothed at the tip, and is a translucent white color. Crucially, bentgrass completely lacks auricles, which are small, ear-like appendages found on many other grasses. The combination of a long, membranous ligule and the absence of auricles is the definitive characteristic for identifying the Agrostis genus.
Common Bentgrass Varieties
The term “bentgrass” refers to multiple species. Creeping Bentgrass (Agrostis stolonifera) is the most widely used in fine turf and is characterized by highly aggressive stolon production. This enables it to form the densest and most uniform surfaces and requires the lowest mowing height.
Colonial Bentgrass (Agrostis capillaris)
Colonial Bentgrass, sometimes called Common Bent, is less aggressive in its spreading behavior, utilizing a combination of short rhizomes and stolons. This variety tends to form a slightly looser turf and can tolerate slightly higher mowing heights than the creeping type.
Velvet Bentgrass (Agrostis canina)
Velvet Bentgrass is distinct for having the finest leaf texture and a darker green color. It is typically the least cold-tolerant and requires the most specific management, but it yields the most luxurious, velvety surface.
Identifying Bentgrass in a Mixed Turf
The presence of bentgrass in a mixed residential lawn is often noticed because of the stark visual contrast it creates. Patches typically stand out due to their much finer texture compared to the wider blades of common grasses like Kentucky Bluegrass or Tall Fescue. This difference makes the bentgrass areas appear wispy and less structured than the surrounding turf. The color of the patch may also be noticeably lighter or different from the main lawn. When homeowners mow their lawn at standard heights of 2.5 inches or more, the fine blades cannot stand upright and instead fall over, creating a matted, puffy, or discolored area. This tendency to mat down at higher cuts is a practical visual indicator for distinguishing it from desirable turfgrasses.