: any of a genus (Tradescantia of the family Commelinaceae, the spiderwort family) of American monocotyledonous, usually trailing or creeping plants with narrow leaves and often short-lived white, rose, blue, or violet flowers and that includes some (such as the inch plant) grown as houseplants especially for their ornamental usually striped foliage : tradescantia

Today I learned that the reason that Tradescantia virginiana aka spiderwort is called “spider” wort or spider lily is because when the stem of a spiderwort is cut, “a viscous stem secretion is released which becomes threadlike and silky upon hardening (like a spider’s web), hence the common name,” says Missouri Botanical Garden’s Plantfinder.

Spiderwort" refers to the sap which dries into web-like threads when a stem is cut. The name "dayflower", shared with other members of the Commelinaceae family, refers to the flowers which open and close within a single day.