Peter Max, whose posters of Day-Glo flowers, butterflies, rainbows, and stars sold by the millions to express the exuberance of the countercultural 1960s, died on Sept. 14 in Manhattan. He was 88.

            His graphic images, incorporating Art Nouveau, Op Art, and psychedelic motifs, lent themselves to a long list of licensed commercial products, from sheets, glassware and shower curtains to airplanes and a stamp for the U.S. Postal Service.

            For his legions of fans, Mr. Max would always remain an avatar of the 1960s happy, innocent phase. “The Beatles had the music; I had the images,” he told Crain’s New York Business in 2007. “Kids would buy the posters and look at them as they listened to the music. It was like their MTV.”