I think that your plant might be a type of Euphorbia, possibly species tirucalli. Does it have a milky latex sap and if so take great care to avoid skin or eye contact. Very painful, personal experience, Joe
This looks like Euphorbia tirucalli (Milkbush or Pencilbush) to me. See http://www.nybg.org/bsci/belize/Euphorbia_tirucalli.jpg