Phalaris arundinacea

Native

Invasive

Wet. Shallow marshes, river banks, roadside ditches; semi-open and open habitats.

May to August

24″ to 72″

This plant often appears in dense colonies that crowd out all other species. It often dominates wet areas.

The blades are flat, ¼″ to ¾″ wide, and up to 20″ long.

The ligule is a thin, papery membrane from just over ⅛″ to just over ⅜″ long. The margin is irregularly jagged, as if torn.

The inflorescence is 2½″ to 7″ long, usually 3″ to 6″, and is borne high above the leaves. It is always evidently branched, at least near the base; the branches are short. When immature, it is compact and resembles a spike. When in full flower, it is open and green or slightly purple or reddish. Later, it turns tan to whitish in color and closes up, becoming narrow and pointed.

Orchard grass (Dactylis glomerata) has an inflorescence that is similar in appearance. However, the leaves are much narrower. The inflorescence is wider with a more blunt tip.

Bluejoint (Calamagrostis canadensis) has a ring of hairs just below the nodes.