On leaf, under side, sub-globular with minute apical nipple. Tip of
latter truncate with fine pore in center. 3 mm. high, 2½-3 mm. wide.
Generally wider through one axis. Smooth; light greenish yellow.
Interiorly a more or less prominent nipple projects inward from the
distal end of the chamber, traversed by the apical pore. Toward
maturity the interior wall is reddened. Gall attached by a short,
cylindric pillar, extending from the leaf into the base of the globular
structure. At the end of summer the galls fall from the leaf, leaving
this pedicel on the leaf. Galls when found are apt to occur in large
numbers, as many as 50-60 commonly being found on a single leaflet.
Collected in Hocking County, Ohio, on _H. microcarpa_, July.
Type specimens at Ohio State University.