NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
Issue link: http://mag.outdoornebraska.gov/i/1378132
58 Nebraskaland • June 2021 this cross-continent forest. As proof, sensitive fern fossils from the time have been found in Greenland, the British Isles and Japan. Later, the Earth's climate cooled and the forests were forced southward, breaking their continental ties and isolating the ferns in suitable habitats in North America and Asia where they persist to this day. The World's Smallest Fern The eastern mosquito fern grows scattered in central Nebraska's shallow playa marshes. Along with six other mosquito fern species, they are the world's smallest fern. The penny-sized plant fl oats on the water's surface, drifting to the whims of wave and wind. The branching stems have many small, overlapping leaves and a few thread-like, dangling roots. The name mosquito refl ects the belief that the ferns, when dense and covering the water's surface, keep mosquitoes from breeding. Mosquito fern spores develop on the leaf's underside and are released in clumps with three small bladder fl oats that eventually deteriorate, releasing the spores. Although they have spores, mosquito ferns reproduce mainly by breaking off of the side branches, each fragment growing into a new plant. Waterfowl spread the fragments, enmeshed in mud on their feet, to other wetlands. Highly sensitive to herbicides carried into wetlands by drift and runoff from adjacent crop fi elds, the plant has declined in Nebraska. Mosquito fern leaves contain chambers that harbor colonies of the nitrogen-fi xing bacteria Anabaena azollae, an attribute that is unique among ferns. This bacteria takes nitrogen gas from the air, which is unusable to plants, and converts it to a nitrate the fern and other plants can use. In China and Vietnam, mosquito ferns have long been used as a green manure in rice paddies, and scientists are developing technologies to expand their use to other areas and crops. Odd Ferns With round, hollow, jointed stems and minute leaves that form a ring of blackish teeth atop each joint, the Equisetums, whose common names are horsetail and scouring-rush, look nothing like other ferns. Until recently, botanists thought these spore- producing plants were closely related to ferns, but not true ferns. Recent DNA analysis, however, shows close genetic ties between the two groups: Equisetums are true ferns that diverged form-wise from the other ferns eons ago. Their giant, now extinct ancestors, the Calamites, soared to nearly 70 feet in height. Four species of Equisetum now inhabit Nebraska. Reaching more than Mosquito fern grows among fl oating-leaf pondweed (center), mud-plantain (upper right) and duckweed (small, green fl oating plants) in a playa marsh at Straight Water Wildlife Management Area in Seward County. Green throughout most of the growing season, the fern turns a brilliant red in fall before dying and sinking to the bottom of the marsh.