I have now found what appears to be V. virgatum growing wild in multiple locations around the county, presumably escaped from cultivation. This particular plant was found surprisingly far back in the woods by a trail.
Savanna. Culm 10-15 cm, leaves 11cm, involute. Bract 3-4cm. Spikelet 3mm, fruits 1-2 per spikelet. Achene tightly wrapped, not mature, rugose, biconvex, 1.6 x 1.5mm +0.5mm tubercle. Bristles plumose at least 2/3 of length, bristles extend to end of achene body.
Wet savanna, powerline that is periodically burned and mowed
Savanna. Spikelet 2.5 x 1.5, very hairy. 1st glume constricted, 0.8mm. About 3 cauline leaves. Lowest cauline leaf 75mm x 8mm, about 10x as long as wide. Old autumn leaves still present, narrower. Nodes bearded. Ligule 3mm hairs.