The Phylogeny Of Angiosperms

Author : John Merle Coulter
Publisher : Forgotten Books
ISBN 13 : 9780428459048
Total Pages : 20 pages
Book Rating : 4.4/5 (59 download)

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Download or read book The Phylogeny of Angiosperms (Classic Reprint) written by John Merle Coulter and published by Forgotten Books. This book was released on 2018-02-06 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from The Phylogeny of Angiosperms The views presented in this paper are in the main based upon numerous investigations conducted by members Of the botanical staff and graduate students. The accounts of these investigations, extending through a period of six years, have been published from time to time, chiefly in the Botanical Gazette, but their bearing upon the problem Of the phylogeny Of Angiosperms has never been presented. It would be confusing to cite the literature involved in this presentation, as it would mean an extensive bibliography and is in the main familiar to students Of the Angiosperms. The purpose is to present in as compact form as possible the bearings of our present knowledge upon a problem Of great obscurity. The phylogeny Of any great group will probably always remain a baffling problem, incapable of actual demonstration, and yet theories Of phylogeny serve to co-ordinate knowledge and stimulate investigation. It should be stated that when similarity Of structure was taken to be a sure indication Of genetic relationships, the problem promised an approximate solution. But since it has been proved that similar structures may develop independently, the difficulty of solution has become apparently insurmountable. The first phase Of the problem has to do with the common or independent origin of the Monocotyledons and Dicotyledons. The current View assumes their monophyletic origin, a View based largely upon the great uniformity of the peculiar development Of the female gametophyte. It is argued that the independent origin Of such exact details Of development and structures is inconceivable. The peculiar female gametophyte Of Angiosperms, however, has been found to vary enough to indicate that it is an extreme expression of tendencies evident in the heterosporous Pteridophytes and Gymnosperms; in other words, an ultimate result of heterospory. Further, nothing is more clear than that heterospory has originated independently in several plant groups; and the assumption that its ultimate expressions, the seed and the angiospermous female gametophyte, have been reached by only one line seems more than improbable. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.