This monothalamous gall is an enlargement of the stem, often just below the flowering branches of blue-curls, Trichostema dichotomum. It is irregularly reniform, tapering somewhat above, ending bluntly below. They average 18 by 6 mm. The surface and coloring are similar to those of the stem. The thick spongy walls enclose a cavity following the general curve of the gall, extending below however, through the wall to a projection at the base of the concave side, where it is separated from the exterior by the epidermis of the stem only, thus providing for the escape of the adult which could not eat its way our, having no mandibles. Abundant.

- FA Stebbins: (1910) Insect galls of Springfield, Massachusetts, and vicinity^©

Reference: https://www.biodiversitylibrary.org/page/21941254