The disclaimer. I am a complete gardening novice/doofus my wife will not even let me pull weeds because I will screw it up.

At our old house we had a beautiful stand of giant bamboo. I have no idea of the correct botanical name. It grew to about 30 ft. with stalks up to 5 inches diameter. There were also a couple of other smaller species but they represent less than 10% of the total. Because I love the giant bamboo I dug up some chunks of root put them in some pots, covered them with dirt and added water. So four out of five pots are now putting out up stalks all is right with the world except...

It has occurred to me that I may have got the root from some of the smaller, scrubby bamboo, instead of the giant that I was aiming for. I would be very bad luck to have selected 4 separate roots none of which are the giant species, but I am not unfamiliar with bad luck.

So is there a way of determining if the immature plants are the giant species?I realize that a thirty foot plant is not going to spring from a 10 inch chunk of root but I don't want to plant a stubby species and then be stuck trying to get rid of it.

Thank you in advance for any help.