It quickly became an invasive species crowding out native marsh grasses. It grows high, 6' to 15' / 2 to 6 meters and can spread up to 16' / 5 m per year with its underground runners that puts down roots as it travels.
There is a native species of the Common Reed but is nowhere near as aggressive.
It produces large cluster like flowers at the top of its stems in late Summer. They are a deep purple but later change grayer due to the growth of long silky hairs.
The decomposing of the massive plant increases the size of the marsh at a rapid pace.
In Winter the plants turns all brown .
The plants are suppressed when grazed by livestock. In Europe it is rarely invasive except in wet areas that aren't grazed. Also burning the marsh grass for two consecutive years will control it.
all photos from ... duckduckgo.com
