The plant - you have the go to the little village that lies at the end of the trail (the trail populated by imps, the one that has the mine on it). If I remember correctly a dragon barrier was in place so I had to go there on foot.
The chalice - it's in the Slayer camp near the zeppelin base. Again I had to swim there because of a dragon barrier.
As usual, you have multiple solutions in acquiring the above two items =)
And yes, you get to kick their asses. After a cool Power Rangers like intro haha.