So I always used to wonder what the cover of issue #30 was really all about, and I'm doing a reread of the entire series now and in issue #32 Doff or Upshaw finds a flower just like the one on the cover of issue #30 and he explains that it is called a violet and it grows where blood was spilled. It's just a tiny panel on one page and isn't explained further and I just thought that was one of the coolest little details and really liked how the issue 30 cover wasn't explained until months later.

So my question is, is there any other reference to Violets and where they grow earlier in the series or is issue #32 the first time it's ever mentioned? Are there any other appearances or references to violets later in the series?

Also, minor side note but I like the similarities between the issue #54 cover and the issue #30 cover.