Symplocos tinctoria (the common sweetleaf,[2] horse-sugar, or yellowwood) is a deciduous or evergreen shrub or tree. It is recognized by pith of twigs chambered; by foliage not notably aromatic when bruised, leaves finely hairy beneath. The sweetleaf gall, Exobasidium symploci, only grows on this plant,
Sweetleaf gall

James H. Miller & Ted Bodner, Southern Weed Science Society [CC BY 3.0]
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Bugwood.org, via Wikimedia Commons