Rose - it is funny that you have one of these, I just picked up one Saturday. You have Euphorbia platyclada. Most Euphorbia have a tiny flower with 5 symetrical 'parts' (I don't know the right word), then this tiny flower is surounded by bracts, which are modified leaves. In E. millii it is two red bracts, in Poinsettia it is a whorl of red or colored leaves. I am fairly certain you have E. platyclada, one of the Euphorbs that does not have colorful bracts surrounding the flower. Really fun looking dead stick plant. Don't ask me what it needs to stay alive, I have only had mine 5 days and I have not done my homework yet. Let me know what you find out. It is from Africa, or Madegascar, but I don't know more precisely than that.