Koval distillery in Chicago makes a 100% rye whiskey. I'm not sure how their current line of whiskeys differs from the stuff they put out previously; when I tasted it, it was under the Lion's Pride label and it was called Dark Rye, being aged longer (?) and in more heavily charred barrels (??) than their Rye. I think their current rye whiskey is more similar to what they used to call their Dark Rye, but I could be wrong on that.
Anyway, I think the vegetal thing is right on, and another flavor I find in rye and in Koval's rye whiskey particularly, is violet, like the way the flower smells. I find a bubblegum taffy sort of sap thing in more aged ryes like VWFRR, which could be a progression of the grassy, flowery characteristics, though on the other hand, it could be all barrel as far as I know.