So Schlaftraum’s flowers are indeed a euphemism for trug. Raublut, directly after coming of age, was assigned to work at a villa where he worked for five years, but it is now closed and has no lady. The villa had a greenhouse in which they grew and were treasured, and can seemingly not be found anywhere else.

I’m thinking that the villa he was assigned is the one for seeds of Adalgisa, hence his extensive knowledge of them. Trug can’t be found elsewhere, it’s probably imported from Lanzenave, the country that also sends the seeds…