They curl around the culm as if holding on tight to the stem to avoid being blown away. Left is a variant , or biotype , of quackgrass. Notice that it is growing close to the ground, a prostrate habit . When competition for light is not a problem, being prostrate allows a plant to exploit more surface area. This allows it to capture more light, and allows it to spread more rhizomes over a larger area of the bud bank.
Prostrate habit is also important in terms of herbicide control .
Having larger surface area of land also exposes more leaf area to herbicide spray and uptake from overhead applications. Notice that is has a horizontal habit, and progressively angles upward at each node, gradually pointing upward. Another variant of quackgrass is featured left, an upright shoot biotype . The culms of this plant are vertical, and the plant covers less surface area. This upright habit also has important implications for its ability to resist herbicides.