No, plants don’t fertilize themselves. But they do engage in an interesting process called auto fertilization. Some leguminous plants, like clover and soybeans, have the ability to form a symbiotic relationship with nitrogen-fixing bacteria (such as Rhizobium). These bacteria lives in specialized root nodules and convert atmospheric nitrogen into ammonia. In return, the plant provides the bacteria with sugars and shelter. So, in a way, these plants do fertilize themselves by hosting their own nitrogen factories!