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Gnetae
Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three relict genera: ''Gnetum'' (family Gnetaceae), ''Welwitschia'' (family Welwitschiaceae), and '' Ephedra'' (family Ephedraceae). The earliest unambiguous records of the group date to the Jurassic, and they achieved their highest diversity during the Early Cretaceous. The primary difference between gnetophytes and other gymnosperms is the presence of vessel elements, a system of small tubes (xylem) that transport water within the plant, similar to those found in flowering plants. Because of this, gnetophytes were once thought to be the closest gymnosperm relatives to flowering plants, but more recent molecular studies have brought this hypothesis into question, with many recent phylogenies finding them to be nested within the conifers. Though it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gnetum Luofuense
''Gnetum luofuense'', also known as (), is a species of gymnosperm in the family Gnetaceae. It is native to southeastern China and is considered a near threatened species. Distribution and habitat ''Gnetum luofuense'' is native to southeastern China and can be found in Fujian, Guangdong, southern Jiangxi, and Hong Kong, with the type (biology), type locality being Mount Luofu, Luófú Shān in Guangdong province. It grows in dense, moist forests at elevations of to . Description ''Gnetum luofuense'' is a dioecious vine with purplish-brown bark. The Glossary of leaf morphology#Oblong, oblong or oblong-Glossary of leaf morphology#Ovate, ovate leaves may be papery or leathery in texture and measure by . Ecology Pollination occurs from May to July, with seeds reaching maturity from August to October. Nocturnal moths appear to be the predominant pollinator of this species, but other insects often visit the Strobilus, strobili without pollinating. Asian honey bees (''Apis cerana'') ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vessel Element
A vessel element or vessel member (also called a xylem vessel) is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are found in most angiosperms (flowering plants) and in some gymnosperms such as cycads and ''Ephedra (plant), Ephedra'', but absent in conifers. Vessel elements are the main feature distinguishing the "hardwood" of angiosperms from the "softwood" of conifers. Anatomy Xylem is the tissue in vascular plants that conducts water (and substances dissolved in it) upwards from the roots to the shoots. Two kinds of cell are involved in xylem transport: tracheids and vessel elements. Vessel elements are the building blocks of vessels, the conducting pathways that constitute the major part of the water transporting system in flowering plants. Vessels form an efficient system for transporting water (including necessary minerals) from the root to the leaves and other parts of the plant. In secondary xylem – the xylem that is prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center. The female gametophyte — specifically termed a ''megagametophyte'' — is also called the ''embryo sac'' in Flowering plant, angiosperms. The megagametophyte produces an ovum, egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule. On the basis of the relative position of micropyle, body of the ovule, chalaza and funicle, there are six types of ovules. Location within the plant In flowering plants, the ovule is located inside the portion of the flower called the gynoecium. The Ovary (plants), ovary of the gynoecium p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bract
In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look different from the parts of the flower, such as the petals or sepals. A plant having bracts is referred to as bracteate or bracteolate, while one that lacks them is referred to as ebracteate or ebracteolate. Variants Some bracts are brightly coloured which aid in the attraction of pollinators, either together with the perianth or instead of it. Examples of this type of bract include those of '' Euphorbia pulcherrima'' (poinsettia) and '' Bougainvillea'': both of these have large colourful bracts surrounding much smaller, less colourful flowers. In grasses, each floret (flower) is enclosed in a pair of papery bracts, called the lemma (lower bract) and palea (upper bract), while each spikelet (group of florets) has a further pair o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapomorphy
In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxon, taxa and is therefore Hypothesis#Scientific hypothesis, hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies Homology (biology), homology. Examples of apomorphy are the presence of Terrestrial locomotion#Posture, erect gait, fur, Evolution of mammalian auditory ossicles, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a Terrestrial locomotion#Posture, sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Female Ephedra Californica Cone - Journal
An organism's sex is female (symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes (unlike isogamy where they are the same size). The exact mechanism of female gamete evolution remains unknown. In species that have males and females, sex-determination may be based on either sex chromosomes, or environmental conditions. Most female mammals, including female humans, have two X chromosomes. Characteristics of organisms with a female sex vary between different species, having different female reproductive systems, with some species showing characteristics secondary to the reproductive system, as with mammary glands in mammals. In humans, the word ''female'' can also be used to refer to gender in the social sense of gender role or g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gnetum Gnemon BotGardBln1105C
''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect-pollinated as their fossils occur in association with extinct pollinating scorpionflies. Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the ''Gnetum'' lineages now found in Africa, South America and Southeast Asia are the result of ancient long-distance dispersal across seawater. Their leaves are rich in phytochemicals such as flavonoids and stilbenes. Of the species studied so far, ''Gnetum'' have photosynthetic and transpiration capacities which are considerably lower than those of other seed plants, due to the absence of multiple chlo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephedra Distachya (female Plant In Bloom)
''Ephedra distachya'' is a shrub in the family Ephedraceae that stands about 25 cm to 50 cm high. The shrub grows in many parts of the world, including southern and central Europe and western and central Asia. Its local names include ''somlatha''. Ephedra distachya lives on grey dunes which are fixed and stable sand dunes that are covered in continuous vegetation. Subspecies #''Ephedra distachya'' subsp. ''distachya'' – central + southern Europe, southwestern + central Asia #''Ephedra distachya'' subsp. ''helvetica'' (C.A.Mey.) Asch. & Graebn. – Switzerland, France, Italy, Slovenia, Austria History ''Ephedra'' is part of a group of plants called ‘gnetophytes’. These plants have hardly changed in the past 100 million years, and are thought to be relics of an ancient flora. The leaves of ''Ephedra'' are tiny and scale-like. Gnetophyte leaves evolved independently from leaves in flowering plants. ''Ephedra'' produces the alkaloid ephedrine, which has been shown to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Welwitschia Mirabilis S&J6
''Welwitschia'' is a monotypic genus of gnetophytes containing only the species ''Welwitschia mirabilis''. It is named after the Austrian botanist Friedrich Welwitsch, who documented the plant in the 1850s. In common use, it is sometimes referred to as the tree tumbo. It is native to Angola and Namibia, where it grows in the extreme conditions of the Namib desert, tolerating high heat and low precipitation. ''Welwitschia'' is the only living genus of the family Welwitschiaceae and order Welwitschiales, and is one of three extant genera of gnetophytes, alongside ''Gnetum'' and '' Ephedra''. ''Welwitschia'' is well known for its unique morphology. The plant only has two leaves that grow out of a large woody stem, dubbed a crown, and continue to grow over the plant's entire life. ''Welwitschia'' is one of the longest-living plants on Earth, with some individuals being thousands of years old. As such, the leaves can become quite large, often reaching several meters in length. Like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephedra (plant)
''Ephedra'' is a genus of gymnosperm shrubs. there were 77 recognized species. The various species of ''Ephedra'' are widespread in many arid regions of the world, ranging across southwestern North America, southern Europe, northern Africa, southwest and central Asia, northern China, and western South America. It is the only extant genus in its family, Ephedraceae, and order, Ephedrales, and one of the three living members of the division Gnetophyta alongside ''Gnetum'' and ''Welwitschia.'' In temperate climates, most ''Ephedra'' species grow on shores or in sandy soils with direct sun exposure. Common names in English include joint-pine, jointfir, Mormon-tea, or Brigham tea. The Chinese name for ''Ephedra'' species is ''mahuang'' (). ''Ephedra'' is the origin of the name of the stimulant ephedrine, which the plants contain in significant concentration. Description The family Ephedraceae, of which ''Ephedra'' is the only extant genus, are gymnosperms, and generally shrubs, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
