Though this grass would not be firm enough to clean a bottle, it certainly looks like a bottle brush.
It is medium-sized grass: 60 cm – 1.5 m in height.
Bottlebrush grass is found in June – August.
It has fairly large V-shaped flower clusters with long stiff bristles.
Bottlebrush Grass grows in rich deciduous or mixed forests and river banks, especially in wet areas in beech-maple-hemlock stands and in swamps.
It is native to eastern North america.
The stem leaves are fairly wide.
Miles Hearn