As the title states, I'm playing through Aquaria for the first time and have been collecting all of the treasures... However, I think I've screwed up, and would appreciate some confirmation on whether I'm stuck with an imperfect game now.

I need only two more treasures, the Mutant Costume(which I am not that concerned with and is not the topic of my question) and the Glowing Plant. The problem is though, concerning the Glowing Plant, every guide I read points me towards "a hidden cave on the same map that you acquire the Glowing Seed treasure, between the two upper passageways."
I'm pretty sure I know of the hidden cave, but the weird thing is, I think the first time I passed through that hidden cave, I verse'd the plant there like I would have anywhere else... and a white fish popped out instead of a consumable item. I thought this was weird at the time, but upon reflection, I realize that plant might have been the Glowing Plant treasure I was looking for all along.
I was just wondering if it is possible to accidentally destroy the Glowing Plant treasure--if it's disguised as a regular verse plant. Or am I just missing the location entirely? There can't be that many hidden caves on the same map.