Dayflower n. : A genus consisting mostly of tropical perennial herbs (Commelina), having ephemeral flowers.

Example:
Is the Blue Dayflower (Commelina communis) a an actual ornamental flower or a weed?

Taxonomy
Asiatic Dayflower, flower, plant, seeds, petal, stamens, spathe, cells, Commelina communis, annual plant, species, ovate, upper margins, flower blooms, ground, stems, leaves, seed capsule.

Defination from the web:
Dayflower forms colonies that can exclude other species of plants. ... Like the native Commelina erecta (Erect Dayflower), its flowers have a small lower petal that is white, whereas the flowers of other Commelina spp. ...