20, is a composition by Austrian composer Arnold Schoenberg scored for coloratura soprano, celesta, harmonium, and harp.
The text is taken from a poem of the same name by Maurice Maeterlinck (title of the French original: "Feuillage du cœur").
The work is also notable for the extreme demands made on the singer which at one point has to ascend to a high F (pianissimo), nearly two-and-a-half octaves above middle C. The work was completed on 9 December 1911 and premiered by Marianne Rau-Hoeglauer in Vienna in April 1928 under the direction of Anton Webern.
Herzgewächse is one of Schoenberg's freely atonal works and one in which the music attempts to accurately reflect the meaning of the words.
The voice runs parallel to the words of the poem, as it tries to follow the meaning implied: when the singer sings "sink to rest", she descends to a very low register; however, when she sings "imperceptibly ascending",[1] she progressively rises to one of the highest pitches in the piece.