BARBERTON:The city is hosting an anniversary party, and everyone is invited. The Barberton Mum Fest is celebrating the 20th year the city has honored the chrysanthemum. The city declared the mum its official flower in 1957 during the term of Mayor Catherine Dobbs. It was chosen because of the presence in Barberton of Yoder Brothers horticulture company, said Lisa McLean, chairwoman of the event each year since its inception.