Hhhmmmm... very good question. "There are a number of substitutes, perhaps you might want to consider rosemary, meadowsweet or lavender?" she mused, at some of the accessible options. At any rate, that was some food for thought, the Ravenclaw would figure it out.

...


Seren was pleased to here the students enjoyed the lesson, personally it was a bit tame, but it was a part of the curriculum... so it was best to get it done and dusted. "You're welcome," she replied to most, but her eyes popped at Minerva's gratitude. It would help her in Uni studies? She was... studying potions? Healing? Something along those lines? "Excellent, I'm so glad to hear it," she beamed. The only thing that brightened the smile of her face was a punny farewell from the Head Girl. Tea-rific? Seren chuckled, "Wonderful," she replied, unable to think of a pun in return. Shame.

Checking the time quickly, her brows rose in alarm. Right then, time to get moving.
"Finish up what you're doing, tidy and off to your next class please... or you'll be late!" she announced to the remaining students. "You'll have plenty of time to complete what you haven't yet done, for homework."

And speaking of... she needed to go back to her office and write up the notice. She lingered long enough to usher the last of the students out, before checking everything was in order and departing herself.