What is the origin and history of fern plant? Information on fern plant origin and history.
ORIGIN OF LIVING FERNS
The major groups of living ferns have fossil records; their ancestry can be traced with reasonable but not absolute precision. Current evidence points to the fossil fern order Botryopteridales (Inversicatenales) from the Carboniferous as the most logical ancestor for most or even all living ferns. The Botryopteridales are more similar to the living ferns than are other groups of ancient ferns.
The fem orders Ophioglossales and Marattiales are evolutionarily quite distinct from other living ferns and are less like the Botryopteridales than are the other living ferns. Nevertheless, it is likely that both orders did evolve from the Botryopteridales. The Ophioglossales lacks a fossil record earlier than the Eocene. The Marattiales is known since the Pennsylvanian, when the tree fern Psaronius was abundant.
The Osmundales evolved as a separate line from the Botryopteridales and has a more continuous fossil record than any other fern group. Grammatopteris, from the lower Permian, is possibly transitional between later genera of this line and the Botryopteridales. Zalesskya and Thamnopteris, small tree ferns from the late Permian, are ancestors of modern Osmundales, as are several Mesozoic genera that resemble living genera.
The Salviniales and Marsileales are represented by mostly Tertiary and a few Cretaceous fossils similar to living forms. Therefore, their origin is rather conjectural. The two groups probably are not closely related. The Salviniales may have arisen directly from the Botryopteridales, although it shares some characteristics like sorus position with primitive members of the Polypodiales. The Marsileales may also have arisen from the Botryopteridales but also shows some similarities with the Schizaeales.
The Schizaeales is linked to the Botryopteridales through fossilized leaves and sporangia represented by Senftenbergia in the Carboniferous and Schizaeopsis in the Cretaceous. More recent fossil genera of the Schizaeales are close to living genera of the order.
The Gleicheniales is represented by Phlebopteris, Matonidium, and other fossil fertile leaves from the Mesozoic belonging to the Matoniaceae. Oligocarpia from the late Paleozoic is probablv referable to the Gleicheniaceae; several fertile leaf genera from the Triassic are undoubtedly in that family.
The earliest known fossils of the Polypodiales are from the Mesozoic, at which time some modern genera were already formed. The Mesozoic fossils are referable to the more primitive families of the order. Among the Cyatheaceae are leaf fragments and sporangia of Protopteris from the Lower Cretaceous and Alsophilites and Protocyathea from the Jurassic. The minor family Dipteridaceae is represented in the Lower Cretaceous by fossilized fertile leaves of several genera, including Dictyophyllum and Hausmannia. Many fossils of the Polypodiales are known from the Cenozoic, virtually all of them referable to modern genera.
The scientific study of ferns has developed in the last 300 years. The various kinds and patterns of tissues found in ferns were first studied by Nehemiah Grew and Marcello Malpighi in the 17th century. Carl Linnaeus classified ferns in the 18th century using principally characters of the spore-bearing leaves. His classification often grouped unrelated kinds of ferns together. Later botanists broadened the basis of classification. Today characters from all parts of the plant are used, and, although some problems remain, related ferns are usually classified together.
In the early 1800’s the function of spores was discovered with the improved microscopes that became available. Wilhelm Hofmeister traced the entire intricate fern life cycle by 1850. Since that time, several asexual variations of the typical sexual cycle have been described.
Early in the 20th century Karl von Goebel and Frederick Bower published books describing the details of fern structure, which were helpful in improving fern classification. Since then this work has been extended by experimentally dissecting live plants, by growing small portions of plants on artificial nutrient cultures, and by subjecting plants to various chemicals and types and amounts of light. This work has made it possible to understand something of how fern structures develop.
Research on the chromosomes in the nuclei of fern cells and on chromosome numbers, which are characteristic of different kinds and groups af ferns, began in the late 19th century. Since 1950 these researches have advanced greatly. Classification also has been improved by further examinations of life cycles as well as by evaluations of the constantly increasing data on structure. In recent years chemicals found in ferns have shown promise as an aid in classification. They also are interesting in themselves and may prove useful as drugs and in insect control.