Rhododendron Society. 7:30 p.m. Christ Church-Episcopal, Parish Room, 15th and H sts., Eureka. Don Wallace of Singing Trees Gardens presents "The King of Shrubs" slide show illustrating the use of rhododendrons in landscaping. Carol Dunning leads the Rhodo 101 session "Using Rhodies in Flower Arrangements." Refreshments. 443-1291.