"A Day in the Life of a Tree", written by Brian and Rieley, is about a tree succumbing to the effects of environmental pollution. A harmonium, an antique pump organ, and a smaller pipe organ provide accompaniment. In the opinion of critic John Bush, the song's subject appeared to be autobiographical: "one of Brian's most deeply touching "and" bizarre compositions...lamenting his long life amid the pollution and grime of a city park while the somber tones of a pipe organ build atmosphere." According to Jardine, Rieley sang the song when "no one would sing it because it was too depressing." Leaf quoted an anonymous friend of Brian's saying that Brian was "choked up" after hearing Rieley's vocal performance of the song, because "he really related to the song. It was about him."