Kokiʻo keʻokeʻo flowers have the most scent in the early morning when flowers open or in the early evening before they close.
It has a red enter or staminal (stamen) column. The white flowers may change to pink, especially towards the end of the day.
I've been captivated by Hibiscus since I learned that the Rose of Sharon, the flower I am named for, is actually in the hibiscus family! Here in Hawaii, they come in many glorious colors. This luminous white one was found on one of my excursions around the island.