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Asplenium Tutwilerae
''Asplenium tutwilerae'' (Tutwiler's spleenwort or Scott's fertile spleenwort) is a rare epipetric fern found only in Hale County, Alabama, United States. ''A. tutwilerae'' is a fertile allotetraploid, formed by the chromosomal doubling of a specimen of the sterile diploid ''A. × ebenoides'', a hybrid of ''A. platyneuron'' and ''A. rhizophyllum''. Except for its spores, which are fertile rather than malformed, ''A. tutwilerae'' is essentially identical to ''A. × ebenoides'' and was described as part of that species until 2007. It is named in honor of Julia Tutwiler, who discovered the only known wild population at Havana Glen in 1873. Description ''Asplenium tutwilerae'' is a small, compact, evergreen, rock-inhabiting fern that grows in individual clumps. It displays a slight frond dimorphism, with the larger, fertile leaf blades more or less upright, while the smaller, usually sterile blades are tightly pressed against the ground. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sorus
A sorus (pl. sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (plural coenosori) is a compound sorus composed of multiple, fused sori. Etymology This New Latin word is from Ancient Greek σωρός (''sōrós'' 'stack, pile, heap'). Structure In lichens and other fungi, the sorus is surrounded by an external layer. In some red algae, it may take the form of depression into the thallus. In ferns, the sori form a yellowish or brownish mass on the edge or underside of a fertile frond. In some species, they are protected during development by a scale or film of tissue called the indusium, which forms an umbrella-like cover. Lifecycle significance Sori occur on the sporophyte generation, the sporangia within producing haploid meiospores. As the sporangia mature, the indusium shrivels so that spore release is unimpeded. The sporangia then burst and release the spores. As an aid to identification The shape, arrangemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellular organisms, the zygote is the earliest developmental stage. In humans and most other anisogamous organisms, a zygote is formed when an egg cell and sperm cell come together to create a new unique organism. In single-celled organisms, the zygote can divide asexually by mitosis to produce identical offspring. German zoologists Oscar and Richard Hertwig made some of the first discoveries on animal zygote formation in the late 19th century. Humans In human fertilization, a released ovum (a haploid secondary oocyte with replicate chromosome copies) and a haploid sperm cell (male gamete) combine to form a single diploid cell called the zygote. Once the single sperm fuses with the oocyte, the latter completes the division of the second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homologous Chromosome
A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci where they provide points along each chromosome which enable a pair of chromosomes to align correctly with each other before separating during meiosis. This is the basis for Mendelian inheritance which characterizes inheritance patterns of genetic material from an organism to its offspring parent developmental cell at the given time and area. Overview Chromosomes are linear arrangements of condensed deoxyribonucleic acid (DNA) and histone proteins, which form a complex called chromatin. Homologous chromosomes are made up of chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci. One homologous chromosome is inherited from the organism's mother; the other is inherited from the organism ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploid is often used to describe cells with three or more chromosome sets. Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle. Half ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with only one copy of each chromosome ( haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome. Later on, during fertilisation, the haploid cells produced by meiosis from a male and female will fuse to create a cell with two copies of each chromosome again, the zygote. Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells, each with half the number of chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopolyploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains one or more chromosomes and comes from each of two parents, resulting in pairs of homologous chromosomes between sets. However, some organisms are polyploid. Polyploidy is especially common in plants. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Males of bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis, the sporophyte generation is diploid and produces spores by meiosi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herb Wagner
Warren Herbert Wagner Jr. (August 29, 1920 – January 8, 2000) was an eminent American botanist who was trained at Berkeley with E.B. Copeland and lived most of his professional career in Michigan. History Wagner was instructed in the ways of plant microphotograph and embryology by Marion S. Cave. Wagner was a longtime faculty member at the University of Michigan. He was most respected among his colleagues and students for his genius in discerning and articulating the differences in form between plant species in the context of their variation with environmental factors. He developed, in the early 1960s, the first algorithm for discerning phylogenetic relationships among species based upon their respective character states observed over a set of characters. This work was honored by James Farris and Arnold Kluge in their later appellation of related algorithms as "Wagner parsimony." Wagner became a pteridologist later in life, specializing in ferns, especially the Botrychi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucien Underwood
Lucien Marcus Underwood (October 26, 1853 – November 16, 1907) was an American botanist and mycologist of the 19th and early 20th centuries. Early life and career He was born in New Woodstock, New York. He enrolled at Syracuse University in 1873 and graduated in 1877. He earned his masters in 1878 and finally and completed his PhD in 1879 under Alexander Winchell. During his graduate school, he taught at Cazenovia Seminary for two years. After a year's teaching at Hedding College, in 1880 he was appointed professor of geology and botany in Illinois Wesleyan University. In 1883, he was appointed professor of geology, botany, and zoology at Syracuse. In 1890, he accepted the Morgan Fellowship at Harvard University to study the Sullivant and Taylor collection of hepatics. In 1891 he became professor of botany in De Pauw University. In 1896, after one year stint as a biology professor at Alabama Polytechnic Institute (''Auburn''), Underwood became a professor of botany at Columbi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alabama
(We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Alabama, Baldwin County , LargestMetro = Birmingham metropolitan area, Alabama, Greater Birmingham , area_total_km2 = 135,765 , area_total_sq_mi = 52,419 , area_land_km2 = 131,426 , area_land_sq_mi = 50,744 , area_water_km2 = 4,338 , area_water_sq_mi = 1,675 , area_water_percent = 3.2 , area_rank = 30th , length_km = 531 , length_mi = 330 , width_km = 305 , width_mi = 190 , Latitude = 30°11' N to 35° N , Longitude = 84°53' W to 88°28' W , elevation_m = 150 , elevation_ft = 500 , elevation_max_m = 735.5 , elevation_max_ft = 2,413 , elevation_max_point = Mount Cheaha , elevation_min_m = 0 , elevation_min_ft = 0 , elevation_min_point = Gulf of Mexico , OfficialLang = English language, English , Languages = * English ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asplenium × Boydstoniae
''Asplenium'' × ''boydstoniae'', commonly known as Boydston's spleenwort, is a rare, sterile, hybrid fern. It is formed by the crossing of Tutwiler's spleenwort ( ''A. tutwilerae'') with ebony spleenwort ( ''A. platyneuron''). The hybrid was produced in culture in 1954. It was not discovered in the wild until 1971, when it was found by Kerry S. Walter at Havana Glen, Alabama, the only known wild site for Tutwiler's spleenwort. Walter named it for Kathryn E. Boydston, an expert in fern culture. Except for the tip of its leaf blade, it largely resembles its ebony spleenwort parent. Description ''Asplenium'' × ''boydstoniae'' is a small fern, similar to ebony spleenwort. The stem is a shiny dark brown, its color extending almost to the tip of the leaf blade, where it becomes green. Most of the blade is cut into pinnae, but it has an elongated, lobed tip. The fronds of ''A.'' × ''boydstoniae'' can be up to or long and or wide. The stipe (the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backcross
Backcrossing is a crossing of a hybrid with one of its parents or an individual genetically similar to its parent, to achieve offspring with a genetic identity closer to that of the parent. It is used in horticulture, animal breeding, and production of gene knockout organisms. Backcrossed hybrids are sometimes described with acronym "BC"; for example, an F1 hybrid crossed with one of its parents (or a genetically similar individual) can be termed a BC1 hybrid, and a further cross of the BC1 hybrid to the same parent (or a genetically similar individual) produces a BC2 hybrid. Plants Advantages * If the recurrent parent is an elite genotype, at the end of the backcrossing programme, an elite genotype is recovered. * As no "new" recombination results, the elite combination is not lost. Disadvantages * It works poorly for quantitative traits. * It is more restricted for recessive traits. * In practice, sections of genome from the nonrecurrent parents are often still present and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
