How do white or yellow bracts help attract insect pollinators to some sedges?

In the few genera of Cyperaceae that rely on insects for pollination rather than the wind, the plants have evolved specific visual adaptations to attract pollinators. In these species, the inflorescences are contracted into dense heads, and the associated scales are typically white or sometimes yellow.

If leaflike bracts are present within the inflorescence, these may also be white or yellow. These bracts are usually clustered together beneath the flower heads and arranged radially at right angles to the stem. This coloration serves to attract the pollinator, while the specific arrangement of the flowers ensures that the insect can access the most pollen possible per visit.1