I have a perennial plant called 'Russian' Oregano by the friend who gave me a bit ten years ago. It has a mild oregano-mint flavour, small rounded 'typical' oregano leaves and conical purple or white flower heads, and grows about 60 to 90 cm. tall. It's good for salad, omelets, and pesto type sauces when fresh, but there's no point drying it becasue it loses almost all flavour. It has woody stems, and is invasive if you don't watch it, as it spreads rapidly from the very tough roots out from the central clump.

I've tried to identify it online, since it does not match the description of Russian oregano I've found. In fact, it looks very like a standard Italian type oregano except that the flower heads are looser (stemlets are longer). It has an intense oregano scent , notable if you just brush the plant as you pass, but this does not translate to strong flavour (still good, just need lots). Anyone know this plant?