What is the primary characteristic of annual bluegrass?

The primary characteristic of annual bluegrass is that it displays small open-panicle seedheads. This trait is significant because it helps in the identification of the grass species among cool-season turf grasses. Annual bluegrass typically produces these distinctive seedheads, which differentiate it from other grass types that might have different growth habits or seedhead structures.

The appearance of open-panicle seedheads is especially prominent during the spring, which is when annual bluegrass is actively growing and reproducing. This characteristic is a key factor for turf managers and lawn care professionals when diagnosing turfgrass problems or developing management strategies for this species.

Furthermore, while the other options refer to various attributes that may pertain to other types of grasses, they do not accurately describe annual bluegrass. For instance, its growth patterns are more associated with cooler months rather than primarily during the summer, which distinguishes it from many warm-season grasses. The ability to survive in dry conditions is also not a defining feature of annual bluegrass, as it typically favors well-watered environments. Finally, while annual bluegrass can form a somewhat dense mat, this characteristic is more associated with its ability to spread rather than being a primary defining trait.