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Wood's Cycad
''Encephalartos woodii'', Wood's cycad, is a rare cycad in the genus ''Encephalartos'', and is endemic to the oNgoye Forest of KwaZulu-Natal, South Africa. It is one of the rarest plants in the world, being extinct in the wild with all specimens being clones of the type. The specific and common name both honour John Medley Wood, curator of the Durban Botanic Garden and director of the Natal Government Herbarium of South Africa, who discovered the plant in 1895. Description It is palm tree like, and can reach a height of . The trunk is about in diameter, thickest at the bottom, and topped by a crown of 50–150 leaves. The leaves are glossy and dark green, in length, and keeled with 70–150 leaflets, the leaflets falcate (sickle-shaped), long and broad. ''E. woodii'' is dioecious, meaning it has separate male and female plants; however, no female plant has ever been discovered. The male strobili are cylindrical, long, exceptionally up to , and in diameter; they are a vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Durban Botanic Garden
The Durban Botanic Gardens is situated in the city of Durban, KwaZulu-Natal, South Africa. It is Durban's oldest public institution and Africa's oldest surviving botanical gardens. The gardens cover an area of in a subtropical climate. History Early history The Durban Botanic Gardens was established to participate in the quest of Kew Gardens to establish a series of botanic gardens across the world which would assist in the introduction of economically valuable plants, and to supply plants to Kew that were new to science. The first garden was established in December 1849 by Dr Charles Johnston on the edge of the Berea Ridge next to the Umgeni River (near Quarry Road). However the death of Johnston's wife in 1850 caused him to resign his position overseeing the gardens. A Scot called Mark McKen then took his place and began to establish gardens of plants of economic value such as sugar cane, tea, coffee and pineapples. In 1851 the botanical gardens were relocated closer to to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of ''Eucalyptus'', palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower ( abaxial) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraspecific Competition
Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. By contrast, interspecific competition occurs when members of different species compete for a shared resource. Members of the same species have rather similar requirements for resources, whereas different species have a smaller contested resource overlap, resulting in intraspecific competition generally being a stronger force than interspecific competition. Individuals can compete for food, water, space, light, mates, or any other resource which is required for survival or reproduction. The resource must be limited for competition to occur; if every member of the species can obtain a sufficient amount of every resource then individuals do not compete and the population grows exponentially. Prolonged exponential growth is rare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random Amplification Of Polymorphic DNA
Random amplification of polymorphic DNA (RAPD), pronounced "rapid", is a type of polymerase chain reaction (PCR), but the segments of DNA that are amplified are random. The scientist performing RAPD creates several arbitrary, short primers (10- 12 nucleotides), then proceeds with the PCR using a large template of genomic DNA, hoping that fragments will amplify. By resolving the resulting patterns, a semi-unique profile can be gleaned from an RAPD reaction. No knowledge of the DNA sequence of the targeted genome is required, as the primers will bind somewhere in the sequence, but it is not certain exactly where. This makes the method popular for comparing the DNA of biological systems that have not had the attention of the scientific community, or in a system in which relatively few DNA sequences are compared (it is not suitable for forming a cDNA databank). Because it relies on a large, intact DNA template sequence, it has some limitations in the use of degraded DNA samples. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encephalartos Ferox
''Encephalartos ferox'', a member of the family Zamiaceae, is a small cycad with 35 cm wide subterranean trunk. It gets its name from the Latin word ferocious, likely from the spine-tipped lobes on the leaves of the plant.Norstog, Knut J., and Trevor J. Nicholls. The Biology of the Cycads. New York : Cornell University Press, 1997. It is found naturally on the south-eastern coast of Africa where it has been used by local people for its starch content.Jones, David L. Cycads of the World. Australia: Reed Books, 1993. It is considered to be one of the most popular cultivated cycads. Naming The species was first described in 1851 when material was collected from Mozambique. After looking at material found in Natal, South Africa, it was redescribed as ''E. kosiensis'' Hutchinson. After looking more carefully at the material, the original name was kept, and the redescribed name was no longer used. Habitat ''E. ferox'' is found along the southern coast of Mozambique and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Hybrid
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relict Species
In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a previous geologic epoch. Similarly, a relictual taxon is a taxon (e.g. species or other lineage) which is the sole surviving representative of a formerly diverse group. Definition A relict (or relic) plant or animal is a taxon that persists as a remnant of what was once a diverse and widespread population. Relictualism occurs when a widespread habitat or range changes and a small area becomes cut off from the whole. A subset of the population is then confined to the available hospitable area, and survives there while the broader population either shrinks or evolves divergently. This phenomenon differs from endemism in that the range of the population was not always restricted to the local region. In other words, the species or group did ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutant
In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It is a characteristic that would not be observed naturally in a specimen. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene. Mutants arise by mutation Mutants arise by mutations occurring in pre-existing genomes as a result of errors of DNA replication or errors of DNA repair. Errors of replication often involve translesion synthesis by a DNA polymerase when it encounters and bypasses a damaged base in the temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encephalartos Natalensis
''Encephalartos natalensis'', the Natal cycad or giant cycad, is a species of cycad that is endemic to the Qumbu and Tabankulu areas of the northern part of the Eastern Cape, and through most of KwaZulu-Natal. The number of mature individuals of this species is declining and the International Union for Conservation of Nature has assessed its conservation status as being "near threatened". Description The Natal cycad grows to a height of or more. It may have a single trunk or may be branched from the base. The trunk is topped by a rosette of large, evergreen, pinnate leaves somewhat twisted near the tip, which may be long. The leaflets are dark green and about wide; they may be untoothed, or they may have one or more small prickles on either edge. The longest leaflets are in the centre of the leaf, and the leaflets nearest the leaf base may be replaced by spines, a fact that distinguishes this cycad from the otherwise similar ''Encephalartos altensteinii''. The Natal cycad is di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encephalartos Altensteinii
''Encephalartos altensteinii'' is a palm-like cycad in the family Zamiaceae. It is endemic to South Africa. The species name ''altensteinii'' commemorates Altenstein, a 19th-century German chancellor and patron of science. It is commonly known as the breadtree, broodboom, Eastern Cape giant cycad or uJobane ( Zulu).Palmer, E. and Pitman, N. ''Trees of Southern Africa''. Cape Town (1972). It is listed as vulnerable due to habitat destruction, use for traditional medicine and removal by collectors. Description This cycad grows up to seven metres tall and may be branched or unbranched. The leaves are straight or curved backwards and up to three metres in length. The leaflets are rigid and fairly broad with one or both margins toothed. There are no prickles at the base of the leaf which distinguishes it from ''E. natalensis''. There are usually two to five greenish-yellow cones up to fifty centimetres long, the female scales covered with protuberances. The cones are poisonous to hum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variety (biology)
In botanical nomenclature, variety (abbreviated var.; in la, varietas) is a taxonomic rank below that of species and subspecies, but above that of Form (botany), form. As such, it gets a three-part Infraspecific name (botany), infraspecific name. It is sometimes recommended that the subspecies rank should be used to recognize geographic distinctiveness, whereas the variety rank is appropriate if the taxon is seen throughout the geographic range of the species. Example The pincushion cactus, ''Escobaria vivipara'' (Nutt.) Buxb., is a wide-ranging variable species occurring from Canada to Mexico, and found throughout New Mexico below about . Nine varieties have been described. Where the varieties of the pincushion cactus meet, they intergrade. The variety ''Escobaria vivipara'' var. ''arizonica'' is from Arizona, while ''Escobaria vivipara'' var. ''neo-mexicana'' is from New Mexico. See also ''Capsicum annuum var. glabriusculum'' Definitions The term is defined in different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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