Coefficient of Conservatism:
Coefficient of Wetness:
Deciduous forests, especially rich moist sites. An interesting shrub, attractive in its early-blooming yellow flowers with strongly exserted stamens. The bud scales form a sort of involucre with conspicuous dark hairs on the outside. The bark is very tough and pliable, the source of the common name.
The alternate entire leaves give the foliage something of the look of the aromatic Lindera, but Dirca has peculiar angular swollen nodes with the petioles ± circular at the base, enclosing the developing axillary bud. A sharp line usually marks the contrast between the green petiole and the reddish brown twig.
An 1868 collection purported to be from Isle Royale is not mapped as the label (not original) is likely in error. This species is not otherwise known from Isle Royale, and the specimen is likely a duplicate of an A. E. Foote collection from Ontonagon County that was erroneously assumed to have been collected on Isle Royale by the University of Michigan party of 1868. In fact, the only Keweenaw Co. collection is a dubious June1885 Farwell sheet (No. 231, BLH) lacking other data.