We all know that Convallaria is a yandere. Specifically an eliminator yandere (she gets hostile if others get near the Knight Commander). But did you know that thus has heavy ties to her flower? All parts of the Lily of the Valley (a.k.a. Convallaria majalis) is poisonous to prevent other animals from eating it's seeds.

Hey... thinking about this I remembered.... Lavender its the other girl said to be a Yandere (and seriously she looks quite frightening).

If im not mistaken, the lavender its said to be the "devils flower" so... maybe there is a relationship with that