...a rosette gall also appears in the apical or axillary buds of S. altissima. These rosette galls are small (3–5 cm in diameter), composed of shortened leaves, and contain a single chamber at their centre .... formed by several very short leaves that are attached together to form a small, rigid cone, and is lined internally by white mycelium.

[this species is re-described in detail in this paper; please refer to it for many more details of gall biology, insect life history, anatomy, and phylogeny]

- Netta Dorchin, Jeffrey B. Joy, Lukas K. Hilke, Michael J. Wise, Warren G. Abrahamson: (2015) Taxonomy and phylogeny of the Asphondylia species (Diptera: Cecidomyiidae) of North American goldenrods: challenging morphology, complex host associations, and cryptic speciation^©