"Not at all," she patiently assures him. She has heard this tone before and knows that a certain gentleness of touch may be required to see him put at ease.

"But there are plates in my workshop on which I am presently growing rather poisonous fungi and I would prefer that no one touch them. There are notes on all of them, of course, but it is only polite to say something directly as well."

See? Perfectly reasonable.