This panic grass is commonly found growing in wet flatwoods, bogs, swamps and disturbed sites nearly throughout Florida. Panicum rigidulum blooms from summer to fall (Wunderlin, 2003). It has a distinctively rigid, dark reddish inflorescence that may be spike-like or its branches may be open and ascending-spreading.
Red-top panicum is a grass. stems robust, erect, smooth, 2-4 ft. tall; leaf blades strongly ribbed, flat, folded at base, 8-20 in. long, to 1/2 in. wide; sheaths loose; ligule tiny; inflorescence at stem tip, dark reddish, rigid, branches pressed to axis or ascending-spreading; spikelets lance-shape, to 1/8 in. long, stalked, tiny hairs at stalk-top