الفهرس | Only 14 pages are availabe for public view |
Abstract For more than a century, taxonomists have recognized two major subgroups of angiosperms, the Monocotyledoneae and Dicotyledoneae. Recently, contemporary taxonomists who are familiar with angiosperms agree that the monocotyledons have been derived from primitive dicotyledon stocks of Ranalian ancestry as an offshot back in the early Mesozoic era. In this respect, the monocots are believed as having advanced status than the dicotyledons. According to recent conception, the monocotyledons, phyllogenetically, are not assumed as monophyletic but polyphyletic in their origin. A great attention has been focused by phylogenetists on the position of the ovary with respect to the other parts of the flower. They take this position into account as a basic criterion for the classification of monocotyledons into minor categories (orders, families and genera). The nature of the inferior ovary is generally discussed on the basis of two theories; appendicular and axile ”receptacular”. |