"Do you think it's Flitterbloom or Devil's Snare?" he asked, nodding towards their plant pot.
"Well… hmm," Justin mused, and flipped through his copy of One Thousand Magical Herbs And Fungi. "It doesn't seem to be moving aggressively."
There was a whoosh from a few rows down.
"Mr. Thomas!" Professor Sprout said sharply. "Please do not entirely incinerate your plant, even if it does turn out to be Devil's Snare! They are small enough that they are merely mildly dangerous!"
"Oh, wait," Justin realized, pointing his wand. "Lumos."
The plant refused to react to the light.
"Probably Flitterbloom, then," he said.
That seemed logical to Harry.
Just to be sure, he went to grab it, and because it didn't immediately try to throttle him Harry decided they were probably correct.
That or it was extremely well-behaved Devil's Snare.