Answer:
Moon- or night-bloomers is the term for flowers which bloom only at night.
Specifically, such flowers tend to be fragrant and white in color. Examples include angel's trumpet (Datura inoxia), evening primrose (Oenothera macrocarpa), mock orange (Philadelphus coronarius), moonflower (Ipomoea alba), and night phlox (Zaluzianskya capensis).