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Topic: Gnetophytes

Related Topics

Spermatophyte

Welwitschiales

Gymnosperm

Vascular plant

Woody plant

Ephedra

Gnetales

Angiosperm

Plant

Pinophyta

Flowering plant

Liana

	MSN Encarta - Search View - Gymnosperm (Site not responding. Last check: 2007-09-14)
		They differ from the other phylum of seed plants, the flowering plants (see Angiosperm), in that the seeds are not enclosed in carpels but rather are borne upon seed scales arranged in cones.
		Gnetophytes are considered from morphological and molecular evidence to share a common ancestry with the flowering plants.
		Cycads and gnetophytes are mainly tropical to subtropical.
	encarta.msn.com /text_761567325__1/Gymnosperm.html (245 words)

	Gymnosperms 304
		This was based upon the presence of vessels in some gnetophytes (all other gymnosperms have only tracheids, angiosperms have both tracheids and vessels) and a type of double fertilization seen in Ephedra.
		The plants are dioecious, the pollen and ovules borne on stalked cones.
		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.
	www.science.siu.edu /plant-biology/PLB304/Gymnosperms.html (1295 words)

	Gnetales description (Site not responding. Last check: 2007-09-14)
		1999), however, found that conifers and gnetophytes are sister groups, and suggested that the evolution of flower-like reproductive structures may have occurred independently in gnetophytes and angiosperms.
		According to this view, angiosperms and gnetophytes are the only extant members of a clade called "anthophytes" to emphasize their shared possession of flower-like reproductive structures.
		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.
	www.botanik.uni-bonn.de /conifers/gnetales.htm (680 words)

	A New Gnetophyte from the Late Carnian
		In gnetophytes, the pollen sacs remained integral on a filamentous axis.
		With the acceptance of gnetopsids as the closest living sister group to the angiosperms, a conflict arose between the traditional phyllosporous interpretation of the carpel and the stachyosporous explanation of the bracteole-bearing axes terminated by an ovule in gnetophytes (Stevenson, 1993; Doyle and Donoghue, 1992).
		The presence on the outside of the female macrocupule of gland-like structures that resemble the stalks that bear pollen sacs on the male macrocupule, and the presence of sterile filamentous appendages inside the male macrocupule that resemble the sterile scales around the ovule, imply an origin from a bisexual macrocupule.
	bcornet.tripod.com /Cornet96/Archaestrobilus.htm (10638 words)

	Lab X - Anthophytes, Glossopterids and Others (4)
		However, gnetophyte vessels have a subtly different developmental origin and thus may not be strictly homologous with those of angiosperms.
		At present, the earliest reasonable record of the gnetophytes is pollen of Triassic and Cretaceous age, which resembles that of modern Ephedra.
		The earliest macrofossil gnetophytes appear in the Early Cretaceous, side-by-side with early angiosperm leave of to Potomac Group (Crane and Upchurch, 1987).
	www.ucmp.berkeley.edu /IB181/VPL/Cup/Cup4.html (1526 words)

	GYMNOSPERMS
		The gnetophytes are reduced to three far-flung and remarkably different genera (each genus in its own order).
		Friedman (1990a, 1990b, 1992, 1994) to consider the gnetophytes as a sister group to the flowering plants.
		If interpreted strictly, the gnetophytes would be a group of conifers.
	comenius.susqu.edu /bi/202/Plants/gymnosperms/gnetophyta.htm (429 words)

	Gnetophyta - Wikipedia, the free encyclopedia
		The plant division Gnetophyta or gnetophytes comprise three related families of woody plants grouped in the gymnosperms, a paraphyletic group of seed plant divisions.
		The gnetophytes differ from other gymnosperms in having wood vessels as in the flowering plants (Angiosperms or Magnoliophytes), and it is thought that Gnetophytes may be the group of spermatophytes most closely related to the flowering plants.
		The Gnetophytes are divided into three orders, each containing a single family and genus:
	en.wikipedia.org /wiki/Gnetae (256 words)

	Gymnosperms (Site not responding. Last check: 2007-09-14)
		Both ginkgo and cycad are dioecious, and have sperm that actually swim through their pollen tubes, while conifer sperm wiggle.
		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)
	blue.butler.edu /~kschmid/302/rvgymnof00.htm (957 words)

	[No title] (Site not responding. Last check: 2007-09-14)
		Angiosperms, gnetophytes and bennettitales have in common flower-like reproductive structures.
		Gnetophytes are monophyletic and their similarities with angiosperms is due to convergent evolution.
		Gnetophytes are paraphyletic, a sister group of the angiosperms, and their similarities are homologous.
	www.cbu.edu /~esalgado/BIOL216/chapter22.doc (4032 words)

	Pinophyta description
		Of this total, one species represents the Ginkgos, 65 represent the Gnetophytes, 206 are Cycads, and the remaining 601 species are Conifers.
		There have lately been notable discoveries (Wollemia, discovered 1994 in Australia), and the affinity of certain cycads, some podocarps and many gnetophytes for tropical rainforest environments means that new discoveries may be made in those taxa as well.
		Conversely, there is a trend toward lumping among the familiar Cupressaceae and Pinaceae, as more taxa formerly seen as valid species are found to be geographical varieties or hybrids in the zone of overlap between congeners.
	www.biologie.uni-hamburg.de /b-online/earle/pinophyta.htm (1209 words)

	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...
		We reserve the right to edit and/or delete text not in practice with established English grammar, scientific literary style, and the Botanical Society of America's Statement on Evolution...
		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...
	www.gigantopteroid.org (663 words)

	distribution
		Gymnosperms include four divisions: cycads, gnetophytes, ginkgos and conifers.
		Cycads are found in tropical and subtropical climates.
		Gnetophytes are found on every continent except Australia and Antarctica.
	www.personal.psu.edu /users/e/a/ead5004/bio110/distribution.html (424 words)

	Gymnosperm Table
		The four phyla of gymnosperms alive today include the cycads (Cycadophyta), the ginkgo (Ginkgophyta), the gnetophytes (Gnetophyta), and the conifers (Coniferophyta).
		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.
	science.kennesaw.edu /biophys/biodiversity/plants/plgymno2.htm (1112 words)

	MADS-box genes reveal that gnetophytes are more closely related to conifers than to flowering plants -- Winter et al. ...
		MADS-box genes reveal that gnetophytes are more closely related to conifers than to flowering plants -- Winter et al.
		of extant seed plants, the gnetophytes are the sister group of
		The phylogenetic relationship between gnetophytes, angiosperms, and conifers is a serious but interesting case of conflict
	www.pnas.org /cgi/content/full/96/13/7342 (5121 words)

	Flowering plant -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-09-14)
		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).
		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.
	www.absoluteastronomy.com /encyclopedia/f/fl/flowering_plant.htm (3803 words)

	BIL 105 - Lecture 24
		Ginkgos are temperate, and don't grow well in Miami.
		Gnetophytes are also temperate, and also not very diverse.
		The only type living in the U.S. are the "joint firs" of the southwestern deserts.
	fig.cox.miami.edu /Faculty/Dana/105F00_24.html (1504 words)

	MADS-Box Genes in Ginkgo biloba and the Evolution of the AGAMOUS Family -- Jager et al. 20 (5): 842 -- Molecular ...
		or of a clade composed of both coniferophytes and gnetophytes
		gamete or oosphere, while conifers, gnetophytes, and angiosperms
		conifers and gnetophytes, and from MADS-box genes belonging
	mbe.oxfordjournals.org /cgi/content/full/20/5/842 (5701 words)

	Gnetae (Site not responding. Last check: 2007-09-14)
		Gnetales Welwitschiales Ephedrales The plant division Gnetophyta or gnetophytes* comprise three related families of woody plants grouped in the gymnosperms, a paraphyletic group of seed plant divisions.
		The Gnetophytes are divided into three orders, each containing a single family and genus: Gnetales: Gnetaceae; Gnetum Welwitschiales: Welwitschiaceae; Welwitschia *Ephedrales: Ephedraceae; Ephedra The Gnetales consist of a single genus, Gnetum, which are mostly woody climbers in tropical forests.
		However, the most well-known member of this group, Gnetum gnemon, is a tree.
	www.smokefreemovies.com /gnetae.html (417 words)

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