The Face in Plant 17v

[-JKP-]

...
Anyway.. any idea what the faces on the ground in the top right drawing represent?

No, I'm not sure of those, just as I am not sure of the plant (although maybe I have something about that plant in my notes).

But... I have noticed that when it's a guy with a beard, it's either some classical sage (often one of the four doctors), or one of the major gods (or Bacchus, as you have noted). Then, of course, one has to figure out if it's a reference to the plant's name, its use, or a personification of the governing planet for that plant.