The only place you know where to get some of the listed herbs and potion ingredients is Snape's collection. Thankfully you have your invisibility cloak, otherwise you're not sure what you would have done!
Lurking near the dungeon entrance to the Potions class, waiting for the current lesson (5th years perhaps?) to end, you mentally ready yourself to get your sneak on! As the bell chimes and the students slowly start to leave the classroom you masterfully navigate between them, sneaking towards the cabinet from which to grab the missing ingredients.
Your reading prompt!
Read a book with plants on
the cover. That can be anything from a tree to a flower, to an acorn.