Can anyone tell me what this is? Looks like an iris from the ground up, but I dug one and it doesn't have the big roots of an iris.

Total height about 2 to 2 and 1/2 ft. No scent from roots or crushed leaves. No stems from flowering. Irises have been blooming here for several weeks, SE Louisiana.

Growing at dry roadside in heavy shade, lots of pine needles and poison ivy.

Link is to scanned image.

Here is a link that might be useful: Mystery roadside plant