I have one stem of an unknown plant left from a bouquet Alicia bought me for Valentine's Day. As the flowers wilted, I'd pull them out until the only thing left was a stem. I'll change the water periodically and this stem has continued to survive. It has sprouted a couple of new leaves, and a new one is coming out now. This stem has no roots, but it continues to survive. I'll post a picture from my phone later.