Macbeth dates back to around 1606.
Tongue of Dog
While the most common name for the plant seems to have been hounds tongue, there are a few instances of it going by another name: Dogs tongue.
I found “Dogs toong” in the The Herball Or Generall Historie of Plantes (1597), page 337.
Here’s another quote, from the ME translation of Guy de Chauliac's Grande ...