SENESCENCE:

The process of aging or growing old. In daylilies, this term most specifically refers to the aging process of the individual flower and the process that causes it to begin to collapse into a spent bloom, wither and dry up after a single day of bloom. From the Latin senescere "To grow old".

After only a single day of bloom, the senescence process causes each bloom to start to break down and eventually dry up and fall away from the scape unless spent blooms are deadheaded.

Photo by Michael Brown, used with permission.