Mrs. dh3, thank you for the identification! Gyula, if your are satisfied with the information received, please detach your picture from the Unidentified flora and fauna album within the next week so that the album remain 'fresh'. Thanks.
Minor point of clarificaiton: there is no "Stachys" family. Stachys is a genus within the mint family. Not all mints have square stems. I'm not sure about Stachys (if thats what this is), but with all the pubescence you can't really tell for certain if this particular stem is square or not.