Here is a patch of grass. Grass, a member of the kingdom Plantae, has organs like those of the kingdom Animalia. Most of your organs and these grass’s organs do stuff, but some don’t do anything. “These organs are vestigial organs. What happened is that evolution and mutations cause once functioning organs to become useless. This is usually because of a lack of need for the organ either because of a replacement or a change in the environment. Grass has a vestigial organ that resembles a flowering plant. However, this flower doesn’t do anything and is useless.