Warner-Lambert plans to close its Anaheim plant.

Officials of the Morris Plains, N.J.-based company said the shutdown, to be completed by the end of the year, will mean the loss of about 300 jobs. The American Chicle Group plant in Anaheim produces a variety of gums, mints and mouthwashes bearing brand names that include Listerine, Clorets and Trident. The first round of layoffs will affect 50 employees and will begin in “the coming weeks,” the company said.