an artificial tree has a lightweight plastic base that may be filled with water or sand to make it heavy enough to support the tree in an outdoor environment without the use of guywires . a sectional vertical support member permits the assembler to vary the height of the assembled tree with ease . a light string is alternately routed up and down between the base and the top of the tree and around the base to give the assembled tree a conical shape that simulates a decorated christmas tree when lit .