I was checking my Rosseyanka persimmon and I noticed that the bamboo post that came with it is green all except for the top inch or so. This is the weirdest thing ever. It went through last winter outside even.
I have scads of various bamboos and have seen cut canes stay green a very long time, but never saw one take off and grow.
Not that this is what you have, but sometimes tropical clumping bamboo is propagated that way. As said, cut canes can stay green for awhile. You'd actually have to see new culms coming out of the ground for it to be alive.