They are really dracaena plants. They can be kept in soil or water. In water, they will rot if more than 2" of the stalk is under water. They also need bright light, frequent water changes and liquid fertilizer like Miracle Grow or Green Green.
I had one that grew really well for a few months in a planted tank with just the leaves above the water in a tank though . Was an impulse when I was at a garden centre (89p).
No it's not .It is bamboo