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| | Gymnosperm Table |
 | | Gnetophytes undergo double fertilization, a feature also found in flowering plants, however in gnetophytes the result is 2 zygotes, while in flowering plants the result is one zygote and one polyploid endosperm. | | | Due to these similarities it is thought that flowering plants and gnetophytes evolved from a common ancestor. | | | These phyla all have in common the production of seeds that not protected within an ovary, rather the seeds are exposed on the upper surfaces of a spore producing structure (eg. |
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http://science.kennesaw.edu/biophys/biodiversity/plants/plgymno2.htm
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| | GYMNOSPERMS |
| | Habit: The gnetophytes are seed plants with decussate leaves. | | | Friedman (1990a, 1990b, 1992, 1994) to consider the gnetophytes as a sister group to the flowering plants. | | | The nature of the ovule and the apparent occurrence of double fertilization in Ephedra caused |
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http://comenius.susqu.edu/bi/202/Plants/gymnosperms/gnetophyta.htm
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| | Gymnosperms |
| | The gnetophytes include the xerophytic Ephedra, which does photosynthesis primarily with its stems, the SW African desert plant Welwitschia, with its two enormous parallel-veined megaphylls, and Gnetum, a genus of tropical vines, shrubs and small trees that share simple pinnate leaves, fleshy female cones and ordinary male cones. | | | Gnetophytes have a number of similarities to angiosperms, including some insect pollination (all 3 groups), a form of double fertilization (though still no endosperm; Ephedra, Gnetum), and lack of archegonia (Gnetum, Welwitschia) | | | Describe at least three advantages an embryo in a seed has compared to an embryo in an archegonium. |
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http://blue.butler.edu/~kschmid/302/rvgymnof00.htm
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| | A New Gnetophyte from the Late Carnian |
| | Probable insect involvement in pollination and the presence of an apical tuft of hair-like appendages on the seed that served in wind dispersal are also consistent with a stem gnetophyte/anthophyte affinity. | | | Consequently, inclusion of Archaestrobilus and any other non-gnetalean seed plant in the gnetophytes is based mostly on reproductive rather than vegetative similarity, just as the inclusion of Sanmiguelia in the angiophytes is based on its overall suite of characters, not on its having all the characters (e.g., leaf morphology) of Cretaceous or extant angiosperms. | | | This latter taxon was herbaceous (also indicated by the occurrence of reproductive axes in a semiaquatic habitat), and was unlike angiophytes (see Ash, 1987) in being non-rhizomatous with long, spirally-arranged, strap-shaped leaves that possessed only two sizes of parallel-veins compared with four sizes in Sanmiguelia (Cornet, 1986). |
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http://bcornet.tripod.com/Cornet96/Archaestrobilus.htm
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| | home page |
| | While the appearance of the whole plant is not well known, some gigantopterids may have been fern-like, while others resembled cycads, cycadeoids, gnetophytes, or small shrubs or vines of flowering plants... | | | What were the ancestors of cycads cycadeoids, gnetophytes, and flowering plants (including palms)? | | | Geophysical mechanisms behind sea floor spreading of the Pacific Basin, island arc orogenesis and "fossilization," and continental and cratonic movements are evaluated to better understand the origins and vicariance dispersal of the forerunners of extant living “fossil” flowering plants, gnetophytes, and cycads... |
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http://www.gigantopteroid.org
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| | Pinophyta description |
| | Of this total, one species represents the Ginkgos, 65 represent the Gnetophytes, 206 are Cycads, and the remaining 601 species are Conifers. | | | In this treatment there are 873 species (as of 29-Jan-1998), or about as many as may be found in the largest genera of flowering plants (such as Acacia). | | | Gymnosperms are woody plants, either shrubs, trees, or, rarely, vines (some gnetophytes). |
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http://www.biologie.uni-hamburg.de/b-online/earle/pinophyta.htm
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| | Gymnosperms 304 |
| | The plants are dioecious, the pollen and ovules borne on stalked cones. | | | Spore evolution from homospory to heterospory to the angiosperm seed (from Scagel et al. | | | As stated in your book, the gnetophytes, together with the angiosperms, have been called anthophytes because of the presence of flowers or flower-like structures. |
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http://www.science.siu.edu/plant-biology/PLB304/Gymnosperms.html
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| | Angiosperm Phylogeny |
| | Endosperm present (resulting from double fertilization, which also occurs in gnetophytes) | | | Sister lineage is unknown, but recent molecular analyses are consistent with gnetophytes being a sister group |
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http://www.emunix.emich.edu/~ghannan/systbot/angiophylogeny.html
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| | Gnetales description |
| | Most phylogenetic analyses based on morphological data agree that among the groups of extant seed plants, the gnetophytes are the sister group of the angiosperms. | | | Five of these genes fall into monophyletic gene clades also comprising putatively orthologous genes from flowering plants and conifers, among them orthologs of floral homeotic B and C function genes. | | | This provides strong molecular evidence for a sister-group relationship between gnetophytes and conifers, which is in contradiction to widely accepted interpretations of morphological data for almost a century. |
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http://www.botanik.uni-bonn.de/conifers/gnetales.htm
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| | distribution |
| | Cycads are found in tropical and subtropical climates. | | | But some plants that live in salt marshes have adapted to deal with high salt content. | | | Gnetophytes are found on every continent except Australia and Antarctica. |
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http://www.personal.psu.edu/users/e/a/ead5004/bio110/distribution.html
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| | Flowering plant -- Facts, Info, and Encyclopedia article |
| | Fossil plants with some identifiable angiosperm characteristics appear in the Jurassic and early (From 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants) Cretaceous (135-65 million years ago), but in relatively few and primitive forms. | | | The first evidence of angiosperms appears in the fossil record approximately 140 million years ago, during the (From 190 million to 135 million years ago; dinosaurs; conifers) Jurassic period (203-135 million years ago). | | | Based on current evidence, it is seems that the ancestors of the angiosperms and the (Click link for more info and facts about Gnetophyte) Gnetophytes diverged from one another during the late (From 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity) Triassic (220-202 million years ago). |
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http://www.absoluteastronomy.com/encyclopedia/f/fl/flowering_plant.htm
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| | [No title] |
| | ORIGIN AND DIVERSIFICATION OF THE ANGIOSPERMS Unique characteristics of the angiosperms are: Flower Close carpels. | | | Gnetophytes are paraphyletic, a sister group of the angiosperms, and their similarities are homologous. | | | Gnetophytes are monophyletic and their similarities with angiosperms is due to convergent evolution. |
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http://www.cbu.edu/~esalgado/BIOL216/chapter22.doc
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| | BIL 105 - Lecture 24 |
| | Gnetophytes are also temperate, and also not very diverse. | | | Ginkgos are temperate, and don't grow well in Miami. | | | The only type living in the U.S. are the "joint firs" of the southwestern deserts. |
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http://fig.cox.miami.edu/Faculty/Dana/105F00_24.html
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| | A View of Life |
| | •Gnetophytes (phylum Gnetophyta) have similarly structured xylem, while none have archegonia, but strobili have similar construction. |
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http://www2.volstate.edu/UGarimella/BIOL1020/Chapter24_files/slide0041.htm
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| | Gnetophyta |
| | Photographs of Gnetophytes from the Virtual Foliage Home Page (University of Wisconsin gopher) |
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http://www.science.siu.edu/landplants/Gnetophyta/gnetophyta.html
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| | Scott's Botanical Links--July 1999 |
| | The New York Botanical Garden has completed cataloging its approximately 10,000 specimens of gymnosperms from North America north of Mexico, including members of Araucariaceae, Cephalotaceae, Cupressaceae (over 40% of the records), Pinaceae (over 55% of the records), Podocarpaceae, Taxaceae and Taxodiaceae (~4%). | | | The absence of Cycadopytes and Gnetophytes puzzles me. Site by New York Botanical Garden. |
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http://www.ou.edu/cas/botany-micro/bot-linx/jul99.shtml
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