Trifolium, composed in 1947 to play with her new friend, the flutist Genevieve Noufflard, stands for Betsy Jolas, over 70 years later, as one of the very few pieces from this distant past, that she still recognises in spite of her future evolution. When Betsy Jolas met Genevieve Noufflard in New York, she was on tour, lecturing on the French resistance movement which she had joined during the war. But Betsy Jolas soon found out about her musical activity and when both returned to Paris shortly after, meetings to play together, were promptly arranged. After much work a deux on Bach, Haydn and many others, Betsy Jolas decided to write a special piece for the two of them. Genevieve Noufflard watched the piece grow, then suggested the title Trifolium to designate its quasi classical structure in three highly contrasting movements. Two years later, in 1949, a concert premiere of Trifolium was given in New York by Samuel Baron, flute, and Robert Cornman, piano.