zinnia - any of various plants of the genus Zinnia cultivated for their variously and brightly colored flower headsflower - a plant cultivated for its blooms or blossoms genus Zinnia - genus of annual or perennial plants of tropical America having solitary heads of brightly colored flowers white zinnia, Zinnia acerosa - subshrub with slender woolly stems and long narrow leaves and flower heads with white rays; southern United States and northern Mexico |