Gall at the base of the stem of Nabalus altissimus, usually in masses surronding stem, often extending down on main root, rarely on main fibres of root, usually about an inch under the ground, sometimes partly above the ground. Galls roughly spherical, 5 mm.—10 mm in diameter each containing 1–10 cells, usually aggregated in irregular cylindrical masses of 2–14, resembling small knobby artichokes or irregular small white potatoes.