Fifteen minutes meant along one thing:

Sprint.

It didn't matter how completely out of breath she was. She only had two out of four ingredients and she was really under pressure, especially since the ruddy Potions classroom was in the dungeons and needed about ten minutes to get down to. She scanned the Greenhouses and reached down, wrapping her hand around the stem of some lavender aaaaaand yanked.

Nooooow, run.

She'd worry about the last ingredient when she got to class.