Fall panicum, Panicum dichotomiflorum, is a grassy summer annual with a zigzag appearance because it bends at its nodes. It has a very rounded stem, prominent midveins in the leaves and a ring of hair as its ligule. The inflorescence, or seed head, is a large, open, branched panicle that takes on a purple tinge when mature.
A summer annual with large round, smooth sheaths that are often bent at the nodes. This weed may reach 7' in height and is found throughout most of the United States in various agronomic and horticultural crops, turfgrass, nurseries, landscapes, and non crop areas. A primary identifying characteristic of this grass weed is the 'zigzagged' growth pattern it takes on due to bending at the nodes.
Fall panicum seedlings are much different from the mature plants in that the seedlings have many hairs on the lower surface of the leaf blades. Leaves are rolled in the shoot, the ligule is a fringe of hairs about 1/2" long, and auricles are absent.
Rolled in the shoot, 4" — 20" long, and auricles are absent. The ligule is a fringe of hairs reaching 2 to 3 mm in length and is often fused at the base. Leaf blades have a conspicuous midvein and are smooth above but sometimes slightly hairy near the leaf tip or leaf base. The lower leaf surfaces of mature plants are without hairs (glabrous) and glossy.
Fall Panicum is often mistaken for Johnsongrass (Sorghum halepense) or Barnyardgrass (Echinochloa crus-galli) prior to seed head formation. However, johnsongrass has a membranous ligule unlike that of fall panicum and johnsongrass seedlings also do not have hairs on the lower leaf surface like those of fall panicum. Additionally, barnyardgrass does not have a ligule at all and barnyardgrass seedlings might only have hairs near the leaf base.