Another reminder about English ivy, an invasive species that strangles and kills trees, like this one in West Cambridge. It’s our local kudzu, all too evident in Cambridge, Belmont and Somerville, taking over gardens and climbing trees. At the beginning of the climb, the roots can be pulled from the trees; once securely attached to the tree or wedged within the interstices of the trunk, the roots of the plant need to be sawed to destroy the vines.