Plants similar to subsp. pubescens, but often shortly rhizomatous, more nearly glabrous, and more deeply and consistently purple throughout. Ligules nearly obsolete; blades usually 2-7 mm wide, often folded or involute, usually pilose adaxially, at least near the base, bases about equal in width to the subtending sheaths. Spikelets 2.6-3.8 mm, usually purple, slender, erect on the pedicels. Lower glumes to 3/4 as long as the spikelets.
Panicum rigidulum subsp. combsii occurs in the same moist habitats as subsp. pubescens, but is much less common. Its long, narrow, purple, often gaping spikelets somewhat resemble those of P. virgatum, which often grows in the same habitats.