Virginia Tech Weed Identification Guide

Green Foxtail: Setaria viridis

Weed Description:  A clump-forming summer annual with a seedhead that resembles a fox's tail.  A weed of many agronomic crops, turf, landscapes, and nurseries.  Found throughout the United States.
Seedling:  Leaves are rolled in the bud, leaf sheaths and blades without hairs, but the leaf sheaths often have slightly hairy margins.  The ligule is a row of hairs approximately 1/2 mm long, therefore this is rarely seen by the casual observer.

Roots:  Fibrous.

Leaves:  Leaf blades may reach 12 inches in length and 5-15 mm in width, and are most often without hairs or only very sparsely hairy.  The leaf sheath is closed and is without hairs, except along the margin near the mouth.  The ligule is short and fringed with hairs to 2 mm long.
Stems:  Erect, without hairs, bent at the nodes, may be branched at the base, reaching 3 feet in height.

Flowers:  The seedhead is a cylindrical bristly panicle, reaching 6 inches in length and 1/3-2/3 inch in width.  Spikelets are approximately 3 mm long, green, and each spikelet has 1-3 bristles that are 5-10 mm long.

Identifying Characteristics:   Characteristic foxtail-like seedhead and leaves with no hairs, which helps to distinguish this weed from both Giant Foxtail (Setaria faberi) and Yellow Foxtail (Setaria glauca).   Giant foxtail may be identified by the presence of many short hairs on the leaf blades, unlike the other foxtails. Yellow foxtail is also similar to green foxtail but has long wiry hairs on the leaf blades where the leaf blades and sheaths meet.