Yoshino's death. His beautiful wife died, so now there are no more cherry blossoms.
源氏
橘の香をなつかしみほととぎす・花散る里をたづねてぞとふ
From Chapter 11 (which is named 花散里)
Looking for the scent of the mandarin orange, which evokes memories of the past, a little cuckoo has sought out this village.
The 橘 is somewhat of a Proustian madleine for the Japanese, being strongly linked with remembering the past.
Prince Genji visits lady 花散里, who he had neglected for years. Smelling the 橘 and hearing the cuckoo, he remembers her. She represents constancy rather than passion.