Publisher Desc.  The "Plena" is an early twentieth-century Afro-Puerto Rican rhythm that was also a popular musical form among sugar-cane workers. The rhythm has its roots in West Africa, and in Diana Sez's engaging original work, the singers establish the rhythm in a clever introduction. The piano accompaniment employs salsa rhythms, hand percussion adds to the textures, and the singers alternate between dance-like melodies and rhythmic improvisations.