Examples from the Web for buttonball
The maple and buttonball or plane-tree were dug up by the boys in the woods the morning of Arbor Day.
Two trees were to be planted, one little maple near the building; another, a buttonball tree, down on the lower grade.
Sycamore, Buttonwood, Buttonball Tree (local and common names).
American buttonball or sycamore trees are distinguished by rough balls which remain hanging on long stems throughout the winter.
But for permanence the maple, the oak, the buttonball are all better.