noun
blue passion flower; Passiflora caerulea
Refers specifically to the blue passion flower, a climbing plant with distinctive clock-like flowers. The name comes from the resemblance of the flower parts to a clock face.
庭にトケイソウが咲いている。
A blue passion flower is blooming in the garden.
トケイソウの花は時計の文字盤に似ている。
The flower of the blue passion flower resembles a clock face.
From the resemblance of the flower's structure to a clock face (時計, tokei, 'clock') plus 草 (sō, 'grass' or 'plant'). The exact historical derivation is uncertain, but the name is a straightforward descriptive compound.