Ferns

Ferns are among the remains of the primitive plants that make up the fossil fuel coal. 10 560 known extant species of ferns in a wide range of height, leaf structure and growing habitat grow freely in nature and are grown as both hardy and tropical horticultural ornamental plants. Edible fiddleheads, tubers and rhizomes of some fern varieties are a food source and used as medicine in some parts of the world. Water floating ferns of the genus Azolla are used as a biological fertilizer in rice paddies due to their significant aptness of fixing nitrogen from the air, as a natural mosquito control, to decrease atmospheric CO2 levels and as a nutritious livestock feed for their rich content of protein, essential amino acids vitamins and minerals. Ferns can aid in remediating contaminated soil and the removal of chemical pollutants from the atmosphere by absorption; ferns used for this purpose should not be eaten. Epiphytic ferns are hosts to a huge diversity of invertebrates. Fern spores are rich in lipids, proteins and calories and are consumed by some vertebrates, small mammals, bats and birds.