Panicum hillmannii is a perennial grass that resembles the related P. capillare (hairy panic) in habitat and appearance.

It is distinguished by slightly stiffer panicles, firmer foliage, the rachilla shortly developed between the upper and lower glumes, the sterile floret which has the palea developed; and larger darker fertile lemma (up to 2mm long) with a prominent crescent-shaped scar at its base.

[5] It was also introduced to Europe, and specimens have been found in France,[6] Belgium, Austria and Germany, although it remains relatively rare there and confined to agricultural weed in maize fields and habitats such as roadsides.

[7] Like several other Panicum species (P. capillare and P. effusum), Hillman's panicgrass can become a tumbleweed under extremely dry conditions, and can become a nuisance in residential areas due to the accumulation of grass stalks.

The plant is potentially harmful for grazing livestock, as it contains saponins causing liver damage in animals.