[2] Prolific Scottish botanist Robert Brown described Panicum effusum in his 1810 work Prodromus Florae Novae Hollandiae et Insulae Van Diemen.

[6] Found across Australia, particularly in the east and Papua New Guinea,[1] hairy panic occurs on low- to medium-nutrient clay soils over shale or conglomerate.

Panicum effusum produces a dry, single-seeded, indehiscent fruit which is eaten by the stubble quail.

[8] In February 2016, the town of Wangaratta, Victoria, was invaded by large numbers of tumbleweeds of the plant, which piled up to roof height in places.

[9] Sheep consuming large quantities of hairy panic within 2–6 weeks of rain can suffer from photosensitivity and the fatal disease called yellow-bighead.