1.
field bindweed (Calystegia japonica); related Calystegia species
A creeping vine with pale pink, trumpet-shaped flowers that open during the daytime. Common as a wildflower along roadsides and field edges in Japan.
Named from 昼 (daytime) + 顔 (face), reflecting that the flowers open during the day. Forms a set with 朝顔 (morning glory) and 夕顔 (moonflower).
Common collocations
Cultural note
The word also became widely associated with the 2014 TV drama "昼顔〜平日午後3時の恋人たち〜", giving 昼顔 a colloquial second meaning of "daytime affair (between married people)" in modern usage.