134-553: Howea forsteriana , the Kentia palm , thatch palm or palm court palm , is a species of flowering plant in the palm family, Arecaceae , endemic to Lord Howe Island in Australia. It is also widely grown on Norfolk Island . It is a relatively slow-growing palm, eventually growing up to 10 m (33 ft) tall by 6 m (20 ft) wide. Its fronds can reach 3 m (10 ft) long. The palm gets its common name from
268-526: A diploid (two copies of each chromosome ) cell. Whereas in fertilization only plasmogamy, or the fusion of the whole sex cells, results, in Angiosperms (flowering plants) a process known as double fertilization, which involves both karyogamy and plasmogamy, occurs. In double fertilization the second sperm cell subsequently also enters the synergid and fuses with the two polar nuclei of the central cell. Since all three nuclei are haploid , they result in
402-411: A filament , or stalk. The anther contains microsporocytes which become pollen , the male gametophyte , after undergoing meiosis . Although they exhibit the widest variation among floral organs, the androecium is usually confined just to one whorl and to two whorls only in rare cases. Stamens range in number, size, shape, orientation, and in their point of connection to the flower. In general, there
536-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
670-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
804-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
938-411: A broad base, stomata and chlorophyll and may have stipules . Sepals are often waxy and tough, and grow quickly to protect the flower as it develops. They may be deciduous , but will more commonly grow on to assist in fruit dispersal. If the calyx is fused it is called gamosepalous. The petals , or corolla, are almost or completely fiberless leaf-like structures that form the innermost whorl of
1072-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
1206-404: A different flower of the same plant, but others have mechanisms to prevent self-pollination and rely on cross-pollination , when pollen is transferred from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination happens in flowers where the stamen and carpel mature at the same time, and are positioned so that the pollen can land on
1340-418: A different plant of the same species. Because the genetic make-up of the sperm contained within the pollen from the other plant is different, their combination will result in a new, genetically distinct, plant, through the process of sexual reproduction . Since each new plant is genetically distinct, the different plants show variation in their physiological and structural adaptations and so the population as
1474-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
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#17328021424581608-485: A few hours; normal temperatures should not go below 10°. It grows readily outside in areas such as southern Australia and northern New Zealand, where it is fairly common in private gardens or as a street tree . In the Northern Hemisphere, it can be grown as far north as southwest England, and grows well in the south of Spain and the southern United States, and will bear flowers and fruit . The coasts of
1742-425: A food source for pollinators. In this way, many flowering plants have co-evolved with pollinators to be mutually dependent on services they provide to one another—in the plant's case, a means of reproduction; in the pollinator's case, a source of food. When pollen from the anther of a flower is deposited on the stigma , this is called pollination. Some flowers may self-pollinate , producing seed using pollen from
1876-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
2010-432: A large endosperm nucleus which is triploid . Following the formation of zygote it begins to grow through nuclear and cellular divisions, called mitosis , eventually becoming a small group of cells. One section of it becomes the embryo , while the other becomes the suspensor; a structure which forces the embryo into the endosperm and is later undetectable. Two small primordia also form at this time, that later become
2144-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
2278-1340: A mate). In pursuing this attractant from many flowers of the same species, the pollinator transfers pollen to the stigmas—arranged with equally pointed precision—of all of the flowers it visits. Many flowers rely on simple proximity between flower parts to ensure pollination, while others have elaborate designs to ensure pollination and prevent self-pollination . Flowers use animals including: insects ( entomophily ), birds ( ornithophily ), bats ( chiropterophily ), lizards, and even snails and slugs ( malacophilae ). Plants cannot move from one location to another, thus many flowers have evolved to attract animals to transfer pollen between individuals in dispersed populations. Most commonly, flowers are insect-pollinated, known as entomophilous ; literally "insect-loving" in Greek. To attract these insects flowers commonly have glands called nectaries on various parts that attract animals looking for nutritious nectar . Some flowers have glands called elaiophores , which produce oils rather than nectar. Birds and bees have color vision , enabling them to seek out colorful flowers. Some flowers have patterns, called nectar guides , that show pollinators where to look for nectar; they may be visible only under ultraviolet light, which
2412-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
2546-458: A noticeable scent. Because of this, plants typically have many thousands of tiny flowers which have comparatively large, feathery stigmas; to increase the chance of pollen being received. Whereas the pollen of entomophilous flowers is usually large, sticky, and rich in protein (to act as a "reward" for pollinators), anemophilous flower pollen is typically small-grained, very light, smooth, and of little nutritional value to insects . In order for
2680-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
2814-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
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#17328021424582948-470: A plant can interpret important endogenous and environmental cues such as changes in levels of plant hormones and seasonable temperature and photoperiod changes. Many perennial and most biennial plants require vernalization to flower. The molecular interpretation of these signals is through the transmission of a complex signal known as florigen , which involves a variety of genes , including Constans, Flowering Locus C, and Flowering Locus T. Florigen
3082-541: A plant of choice for modern hotel lobbies, casinos, and shopping malls. One of the first class facilities of RMS Titanic , such as the Verandah Café (a palm court), had featured a number of potted Kentia palms. During the Edwardian era , around 4 million seeds were harvested annually on Lord Howe Island to satisfy the market for Kentias. In 1912, a Judicial Royal Commission was formed in Australia to investigate
3216-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
3350-404: A sonar-reflecting petal above its flowers, which helps the bat find them, and one species, the cactus Espostoa frutescens , has flowers that are surrounded by an area of sound-absorbent and woolly hairs called the cephalium, which absorbs the bat's ultrasound instead. Flowers are also specialized in shape and have an arrangement of the stamens that ensures that pollen grains are transferred to
3484-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
3618-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
3752-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
3886-491: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
4020-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
4154-528: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
Howea forsteriana - Misplaced Pages Continue
4288-407: A third in 1944. Knuth named his two groups 'Hyphydrogamy' and the more common 'Ephydrogamy'. In hyphydrogamy pollination occurs below the surface of the water and so the pollen grains are typically negatively buoyant . For marine plants that exhibit this method, the stigmas are usually stiff, while freshwater species have small and feathery stigmas. In ephydrogamy pollination occurs on the surface of
4422-517: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
4556-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
4690-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
4824-435: A whole is better prepared for an adverse occurrence in the environment. Cross-pollination, therefore, increases the survival of the species and is usually preferred by flowers for this reason. The principal adaptive function of flowers is the promotion of cross-pollination or outcrossing, a process that allows the masking of deleterious mutations in the genome of progeny. The masking effect of outcrossing sexual reproduction
4958-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
5092-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
5226-416: Is a loss of B gene function, mutant flowers are produced with sepals in the first whorl as usual, but also in the second whorl instead of the normal petal formation. In the third whorl, the lack of the B function but the presence of the C function mimics the fourth whorl, leading to the formation of carpels also in the third whorl. The principal purpose of a flower is the reproduction of the individual and
5360-422: Is a much rarer method, occurring in only around 2% of abiotically pollinated flowers. Common examples of this include Calitriche autumnalis , Vallisneria spiralis and some sea-grasses . One characteristic which most species in this group share is a lack of an exine , or protective layer, around the pollen grain. Paul Knuth identified two types of hydrophilous pollination in 1906 and Ernst Schwarzenbach added
5494-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
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5628-417: Is a way to represent the structure of a flower using specific letters, numbers, and symbols, presenting substantial information about the flower in a compact form. It can represent a taxon , usually giving ranges of the numbers of different organs, or particular species. Floral formulae have been developed in the early 19th century and their use has declined since. Prenner et al. (2010) devised an extension of
5762-404: Is an example of coevolution , as the flower and pollinator have developed together over a long period to match each other's needs. This close relationship compounds the negative effects of extinction , however, since the extinction of either member in such a relationship would almost certainly mean the extinction of the other member as well. Flowers that use abiotic, or non-living, vectors use
5896-427: Is because it is directly connected to the method of seed dispersal; that being the purpose of fruit - to encourage or enable the seed's dispersal and protect the seed while doing so. Following the pollination of a flower, fertilization, and finally the development of a seed and fruit, a mechanism is typically used to disperse the fruit away from the plant. In Angiosperms (flowering plants) seeds are dispersed away from
6030-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
6164-412: Is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
6298-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
6432-677: Is from the Middle English flour , which referred to both the ground grain and the reproductive structure in plants, before splitting off in the 17th century. It comes originally from the Latin name of the Italian goddess of flowers, Flora . The early word for flower in English was blossom , though it now refers to flowers only of fruit trees . The morphology of a flower, or its form and structure, can be considered in two parts:
6566-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
6700-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
6834-541: Is highly reduced or absent). The stem or stalk subtending a flower, or an inflorescence of flowers, is called a peduncle . If a peduncle supports more than one flower, the stems connecting each flower to the main axis are called pedicels . The apex of a flowering stem forms a terminal swelling which is called the torus or receptacle. In the majority of species, individual flowers have both carpels and stamens. These flowers are described by botanists as being perfect, bisexual, or hermaphrodite . In some species of plants,
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#17328021424586968-494: Is known as "genetic complementation". This beneficial effect of outcrossing on progeny is also recognized as hybrid vigour or heterosis. Once outcrossing is established due to the benefits of genetic complementation, subsequent switching to inbreeding becomes disadvantageous because it allows the expression of the previously masked deleterious recessive mutations, usually referred to as inbreeding depression. Charles Darwin in his 1889 book The Effects of Cross and Self-Fertilization in
7102-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
7236-478: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
7370-408: Is only one type of stamen, but there are plant species where the flowers have two types; a "normal" one and one with anthers that produce sterile pollen meant to attract pollinators. The gynoecium , or the carpels , is the female part of the flower found on the innermost whorl. Each carpel consists of a stigma , which receives pollen, a style , which acts as a stalk, and an ovary , which contains
7504-443: Is preferred because it allows for genetic variation , which contributes to the survival of the species. Many flowers depend on external factors for pollination, such as the wind, water, animals, and especially insects . Larger animals such as birds, bats, and even some pygmy possums , however, can also be employed. To accomplish this, flowers have specific designs which encourage the transfer of pollen from one plant to another of
7638-429: Is produced in the leaves in reproductively favorable conditions and acts in buds and growing tips to induce several different physiological and morphological changes. The first step of the transition is the transformation of the vegetative stem primordia into floral primordia. This occurs as biochemical changes take place to change the cellular differentiation of leaf, bud and stem tissues into tissue that will grow into
7772-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
7906-422: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. Flower A flower , also known as a bloom or blossom ,
8040-435: Is the reproductive structure found in flowering plants (plants of the division Angiospermae ). Flowers consist of a combination of vegetative organs – sepals that enclose and protect the developing flower. These petals attract pollinators, and reproductive organs that produce gametophytes , which in flowering plants produce gametes . The male gametophytes, which produce sperm, are enclosed within pollen grains produced in
8174-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
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#17328021424588308-418: Is typically another part. In some families, such as the grasses , the petals are greatly reduced; in many species, the sepals are colorful and petal-like. Other flowers have modified petal-like stamens; the double flowers of peonies and roses are mostly petaloid stamens. Many flowers have symmetry. When the perianth is bisected through the central axis from any point and symmetrical halves are produced,
8442-574: Is visible to bees and some other insects. Flowers also attract pollinators by scent , though not all flower scents are appealing to humans; several flowers are pollinated by insects that are attracted to rotten flesh and have flowers that smell like dead animals. These are often called carrion flowers , including plants in the genus Rafflesia , and the titan arum . Flowers pollinated by night visitors, including bats and moths, are likely to concentrate on scent to attract pollinators and so most such flowers are white. Some plants pollinated by bats have
8576-530: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
8710-400: The anthers . The female gametophytes are contained within the ovules produced in the ovary . Most flowering plants depend on animals, such as bees, moths, and butterflies, to transfer their pollen between different flowers, and have evolved to attract these pollinators by various strategies, including brightly colored, conspicuous petals, attractive scents, and the production of nectar ,
8844-414: The calyx , corolla , androecium , and gynoecium . Together the calyx and corolla make up the non-reproductive part of the flower called the perianth , and in some cases may not be differentiated. If this is the case, then they are described as tepals . The sepals , collectively called the calyx, are modified leaves that occur on the outermost whorl of the flower. They are leaf-like, in that they have
8978-401: 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. About 14% of these had been described by 2011. All species (except viruses ) are given a two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part
9112-499: The cotyledon , which is used as an energy store. Plants which grow out one of these primordia are called monocotyledons , while those that grow out two are dicotyledons . The next stage is called the Torpedo stage and involves the growth of several key structures, including: the radicle (embryotic root), the epicotyl (embryotic stem), and the hypocotyl , (the root/shoot junction). In the final step vascular tissue develops around
9246-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
9380-439: The gizzard of animals or even to germinate better after passing through them. They can be eaten by birds ( ornithochory) , bats ( chiropterochory) , rodents , primates, ants ( myrmecochory ), non-bird sauropsids ( saurochory) , mammals in general (mammaliochory) , and even fish . Typically their fruit are fleshy, have a high nutritional value, and may have chemical attractants as an additional "reward" for dispersers. This
9514-507: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
9648-518: The wind or, much less commonly, water , to move pollen from one flower to the next. In wind-dispersed ( anemophilous ) species, the tiny pollen grains are carried, sometimes many thousands of kilometers, by the wind to other flowers. Common examples include the grasses , birch trees , along with many other species in the order Fagales , ragweeds , and many sedges . They do not need to attract pollinators and therefore tend not to grow large, showy, or colorful flowers, and do not have nectaries, nor
9782-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
9916-663: The 1870s, when seed exports from Lord Howe Island first started. In part this was because the plant thrived in interiors where low light, low humidity, poor air quality and cool temperatures made palms otherwise impossible to grow. One of the earliest growers were the De Clerc family in Belgium, who remained one of the dominant growers of the palm in Europe for the next century. By 1885 the palm had achieved preeminence in Britain, where
10050-461: The Journal of Horticulture commented that: "These Kentias are in greater demand than almost any other palm on account of their great beauty and enduring properties." Another reason for their popularity is attributable to Queen Victoria , who cultivated them in all of her homes and left instructions for Kentia palms to be placed around her coffin while she lay in state. The association with royalty and
10184-626: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
10318-605: The United States, where much of the commercial growing is done in Hawaii before plants are brought to the mainland. As potted plants Kentias are fairly tolerant of neglect: they can withstand low-light conditions, low humidity, infrequent watering and cool temperatures. However, it is advisable to give Kentias bright, indirect light to encourage growth and a more robust appearance; Kentias placed in dark corners with little natural light tend to look leggy and grow very slowly. In
10452-470: The Vegetable Kingdom at the beginning of chapter XII noted, "The first and most important of the conclusions which may be drawn from the observations given in this volume, is that generally cross-fertilisation is beneficial and self-fertilisation often injurious, at least with the plants on which I experimented." Self-pollination is the pollination of the carpel of a flower by pollen from either
10586-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
10720-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
10854-490: The apical meristem, which becomes a whorl of sepals. In the second whorl, both A and B genes are expressed, leading to the formation of petals. In the third whorl, B and C genes interact to form stamens and in the center of the flower C genes alone give rise to carpels. The model is based upon studies of aberrant flowers and mutations in Arabidopsis thaliana and the snapdragon, Antirrhinum majus . For example, when there
10988-404: The appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use the concept of
11122-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
11256-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
11390-582: The bodies of the pollinator when it lands in search of its attractant. Other flowers use mimicry or pseudocopulation to attract pollinators. Many orchids, for example, produce flowers resembling female bees or wasps in color, shape, and scent. Males move from one flower to the next in search of a mate, pollinating the flowers. Many flowers have close relationships with one or a few specific pollinating organisms. Many flowers, for example, attract only one specific species of insect and therefore rely on that insect for successful reproduction. This close relationship
11524-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
11658-711: The capital of Lord Howe Island, Kentia, and the genus name, Howea, from the island itself. The species name "forsteriana" is after Johann Reinhold Forster and Georg Forster , father and son, who accompanied Captain Cook as naturalists on his second voyage to the Pacific in 1772–1775. The species is considered vulnerable by the World Conservation Union . It is cultivated on Lord Howe Island by collecting wild seeds and germinating them for export worldwide as an ornamental garden or house plant . The trade in
11792-517: The collective cluster of flowers is called an inflorescence . Some inflorescences are composed of many small flowers arranged in a formation that resembles a single flower. A common example of this is most members of the very large composite ( Asteraceae ) group. A single daisy or sunflower , for example, is not a flower but a flower head —an inflorescence composed of numerous flowers (or florets). An inflorescence may include specialized stems and modified leaves known as bracts . A floral formula
11926-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
12060-411: The cultivation and marketing of the palm on the island. At the beginning of the 21st century, production of Kentia palm seeds globally stood at between 30 and 40 million. The palm is an elegant plant, and is popular for growing indoors, requiring little light. Out of doors, it prefers a tropical region but will also grow in a cooler climate, and can tolerate temperatures down to -5 °C, but only for
12194-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
12328-484: The existing model to broaden the descriptive capability of the formula. The format of floral formulae differs in different parts of the world, yet they convey the same information. The structure of a flower can also be expressed by the means of floral diagrams . The use of schematic diagrams can replace long descriptions or complicated drawings as a tool for understanding both floral structure and evolution. Such diagrams may show important features of flowers, including
12462-619: The fact that Kentias were quite expensive to buy gave those who could furnish their homes with them a certain prestige. The Palm Courts which became popular in Edwardian hotels like those of The Ritz Hotel in London or the Plaza Hotel in New York all featured Kentia palms, aesthetically pleasing because of their architectural, drooping fronds and the great height they reach at maturity. They continue to be used in such contexts, being
12596-413: The flower is said to be actinomorphic or regular. This is an example of radial symmetry . When flowers are bisected and produce only one line that produces symmetrical halves, the flower is said to be irregular or zygomorphic . If, in rare cases, they have no symmetry at all they are called asymmetric. Flowers may be directly attached to the plant at their base ( sessile —the supporting stalk or stem
12730-497: The flower's stigma. This pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators. Some flowers produce diaspores without fertilization ( parthenocarpy ). After fertilization, the ovary of the flower develops into fruit containing seeds . Flowers have long been appreciated for their beauty and pleasant scents, and also hold cultural significance as religious, ritual, or symbolic objects, or sources of medicine and food. Flower
12864-511: The flowers are imperfect or unisexual: having only either male (stamen) or female (carpel) parts. If unisexual male and female flowers appear on the same plant, the species is called monoecious . However, if an individual plant is either female or male, the species is called dioecious . Many flowers have nectaries , which are glands that produce a sugary fluid used to attract pollinators. They are not considered as an organ on their own. In those species that have more than one flower on an axis,
12998-424: The following two broad groups of pollination methods: Flowers that use biotic vectors attract and use insects , bats , birds , or other animals to transfer pollen from one flower to the next. Often they are specialized in shape and have an arrangement of the stamens that ensures that pollen grains are transferred to the bodies of the pollinator when it lands in search of its attractant (such as nectar, pollen, or
13132-451: The gametophytes also develop inside the spores, i.e., they are endosporic. Since the flowers are the reproductive organs of the plant, they mediate the joining of the sperm, contained within pollen, to the ovules — contained in the ovary. Pollination is the movement of pollen from the anthers to the stigma. Normally pollen is moved from one plant to another, known as cross-pollination , but many plants can self-pollinate. Cross-pollination
13266-471: The northern hemisphere, a northern or northeastern window is best, as greenhouse-grown Kentias cannot tolerate direct sun and will sunburn if placed in such an exposure. The roots are very sensitive to disturbance, so gardeners should only repot Kentias after they have become extremely root bound in their existing pot, and even then should take special care. They appreciate regular water but should be allowed to dry out between waterings. Overwatering, or allowing
13400-483: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
13534-400: The ovary. After penetrating the center-most part of the ovary it enters the egg apparatus and into one synergid . At this point the end of the pollen tube bursts and releases the two sperm cells, one of which makes its way to an egg, while also losing its cell membrane and much of its protoplasm . The sperm's nucleus then fuses with the egg's nucleus, resulting in the formation of a zygote ,
13668-504: The ovule is fertilized by pollen from the same flower or plant, occurs in flowers that always self-fertilize, such as many dandelions . Some flowers are self-pollinated and have flowers that never open or are self-pollinated before the flowers open; these flowers are called cleistogamous ; many species in the genus Viola exhibit this, for example. Conversely, many species of plants have ways of preventing self-pollination and hence, self-fertilization. Unisexual male and female flowers on
13802-524: The ovules. Carpels may occur in one to several whorls, and when fused are often described as a pistil . Inside the ovary, the ovules are attached to the placenta by structures called funiculi . Although this arrangement is considered "typical", plant species show a wide variation in floral structure. The four main parts of a flower are generally defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions or look like what
13936-593: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
14070-534: The perianth. They are often delicate and thin and are usually colored, shaped, or scented to encourage pollination. Although similar to leaves in shape, they are more comparable to stamens in that they form almost simultaneously with one another, but their subsequent growth is delayed. If the corolla is fused together it is called sympetalous. The androecium , or stamens, is the whorl of pollen-producing male parts. Stamens consist typically of an anther , made up of four pollen sacs arranged in two thecae , connected to
14204-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
14338-581: The plant a shrubbier look. They remain relatively expensive to purchase, because the export of seeds from Lord Howe Island is strictly controlled, the germination rate for seeds is low, and the plant is a slow grower, requiring years of nurturing to reach saleable size. In Europe Kentias are primarily nursery-grown in Holland and then sold throughout the continent. They are more popular, less expensive, and easier to purchase in European countries than they are in
14472-451: The plant so as to not force competition between the mother and the daughter plants, as well as to enable the colonization of new areas. They are often divided into two categories, though many plants fall in between or in one or more of these: In allochory, plants use an external vector , or carrier, to transport their seeds away from them. These can be either biotic (living), such as by birds and ants, or abiotic (non-living), such as by
14606-400: The process of pollination. Fertilization , also called Synagmy, occurs following pollination, which is the movement of pollen from the stamen to the carpel. It encompasses both plasmogamy , the fusion of the protoplasts , and karyogamy , the fusion of the nuclei . When pollen lands on the stigma of the flower it begins creating a pollen tube which runs down through the style and into
14740-600: The relative positions of the various organs, including the presence of fusion and symmetry, as well as structural details. A flower develops on a modified shoot or axis from a determinate apical meristem ( determinate meaning the axis grows to a set size). It has compressed internodes, bearing structures that in classical plant morphology are interpreted as highly modified leaves . Detailed developmental studies, however, have shown that stamens are often initiated more or less like modified stems (caulomes) that in some cases may even resemble branchlets . Taking into account
14874-420: The reproductive organs. Growth of the central part of the stem tip stops or flattens out and the sides develop protuberances in a whorled or spiral fashion around the outside of the stem end. These protuberances develop into the sepals, petals, stamens, and carpels . Once this process begins, in most plants, it cannot be reversed and the stems develop flowers, even if the initial start of the flower formation event
15008-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
15142-586: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
15276-446: The roots to sit in water, can induce root rot and kill the palm. An indoor houseplant fertilizer should be applied regularly in the spring and summer to encourage growth. If used indoors, the fronds should be misted three times a week with rainwater to raise the humidity levels and keep the fronds looking green and healthy. Species A species ( pl. : species) is a population of organisms in which any two individuals of
15410-490: The same flower or another flower on the same plant, leading to the creation of a genetic clone through asexual reproduction . This increases the reliability of producing seeds, the rate at which they can be produced, and lowers the amount energy needed. But, most importantly, it limits genetic variation . In addition, self-pollination causes inbreeding depression , due largely to the expression of recessive deleterious mutations . The extreme case of self-fertilization, when
15544-412: The same plant may not appear or mature at the same time, or pollen from the same plant may be incapable of fertilizing its ovules. The latter flower types, which have chemical barriers to their own pollen, are referred to as self-incompatible. In Clianthus puniceus , self-pollination is used strategically as an "insurance policy". When a pollinator, in this case a bird, visits C. puniceus , it rubs off
15678-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
15812-769: The same species. The period during which this process can take place (when the flower is fully expanded and functional) is called anthesis , hence the study of pollination biology is called anthecology . Flowering plants usually face evolutionary pressure to optimize the transfer of their pollen , and this is typically reflected in the morphology of the flowers and the behavior of the plants. Pollen may be transferred between plants via several 'vectors,' or methods. Around 80% of flowering plants make use of biotic or living vectors. Others use abiotic, or non-living, vectors and some plants make use of multiple vectors, but most are highly specialized. Though some fit between or outside of these groups, most flowers can be divided between
15946-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
16080-482: The seed. The ovary, inside which the seed is forming from the ovule, grows into a fruit . All the other main floral parts die during this development, including: the style, stigma, sepals, stamens, and petals. The fruit contains three structures: the exocarp , or outer layer, the mesocarp , or the fleshy part, and the endocarp , or innermost layer, while the fruit wall is called the pericarp . The size, shape, toughness, and thickness varies among different fruit. This
16214-599: The seeds and seedlings is tightly regulated. This plant has gained the Royal Horticultural Society 's Award of Garden Merit . Howea forsteriana gained great popularity as a houseplant in Europe and the United States during the Victorian era , at a time when exotic palms and other plants were avidly collected in England and elsewhere. The Kentia became the quintessential 'parlor palm' beginning in
16348-595: The southeastern Azores and Madeira offer climates similar to its original habitat. It is slow growing, but will eventually reach heights of 6 to 18 metres. Under natural conditions, it grows as a solitary tree. Germination of the seeds is erratic. The closely related Belmore sentry palm ( Howea belmoreana ), also endemic on Lord Howe Island, is a smaller species to 7 metres tall, found mainly as an understorey plant in moist forests . A potted Kentia palm sold in modern-day garden centers generally does not consist of one palm but 2 to 5, planted in clusters as seedlings to give
16482-506: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
16616-439: The species. All flowering plants are heterosporous , that is, every individual plant produces two types of spores . Microspores are produced by meiosis inside anthers and megaspores are produced inside ovules that are within an ovary. Anthers typically consist of four microsporangia and an ovule is an integumented megasporangium. Both types of spores develop into gametophytes inside sporangia. As with all heterosporous plants,
16750-428: The stigmatic covering and allows for pollen from the bird to enter the stigma. If no pollinators visit, however, then the stigmatic covering falls off naturally to allow for the flower's own anthers to pollinate the flower through self-pollination. Pollen is a large contributor to asthma and other respiratory allergies which combined affect between 10 and 50% of people worldwide. This number appears to be growing, as
16884-463: The temperature increases due to climate change mean that plants are producing more pollen , which is also more allergenic. Pollen is difficult to avoid, however, because of its small size and prevalence in the natural environment. Most of the pollen which causes allergies is that produced by wind-dispersed pollinators such as the grasses , birch trees , oak trees, and ragweeds ; the allergens in pollen are proteins which are thought to be necessary in
17018-428: The vegetative part, consisting of non-reproductive structures such as petals ; and the reproductive or sexual parts. A stereotypical flower is made up of four kinds of structures attached to the tip of a short stalk or axis, called a receptacle . Each of these parts or floral organs is arranged in a spiral called a whorl . The four main whorls (starting from the base of the flower or lowest node and working upwards) are
17152-619: The water and so the pollen has a low density to enable floating, though many also use rafts, and are hydrophobic . Marine flowers have floating thread-like stigmas and may have adaptations for the tide, while freshwater species create indentations in the water. The third category, set out by Schwarzenbach, is those flowers which transport pollen above the water through conveyance. This ranges from floating plants, ( Lemnoideae ), to staminate flowers ( Vallisneria ). Most species in this group have dry, spherical pollen which sometimes forms into larger masses, and female flowers which form depressions in
17286-401: The water; the method of transport varies. Flowers can be pollinated by two mechanisms; cross-pollination and self-pollination. No mechanism is indisputably better than the other as they each have their advantages and disadvantages. Plants use one or both of these mechanisms depending on their habitat and ecological niche . Cross-pollination is the pollination of the carpel by pollen from
17420-480: The whole diversity in the development of the androecium of flowering plants, we find a continuum between modified leaves (phyllomes), modified stems (caulomes), and modified branchlets (shoots). The transition to flowering is one of the major phase changes that a plant makes during its life cycle. The transition must take place at a time that is favorable for fertilization and the formation of seeds , hence ensuring maximal reproductive success. To meet these needs
17554-540: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
17688-460: The wind or water. Many plants use biotic vectors to disperse their seeds away from them. This method falls under the umbrella term zoochory , while endozoochory , also known as fruigivory, refers specifically to plants adapted to grow fruit in order to attract animals to eat them. Once eaten they go through typically go through animal's digestive system and are dispersed away from the plant. Some seeds are specially adapted either to last in
17822-419: The wind to effectively pick up and transport the pollen, the flowers typically have anthers loosely attached to the end of long thin filaments, or pollen forms around a catkin which moves in the wind. Rarer forms of this involve individual flowers being moveable by the wind ( pendulous ), or even less commonly; the anthers exploding to release the pollen into the wind. Pollination through water ( hydrophily )
17956-416: Was dependent on some environmental cue. The ABC model is a simple model that describes the genes responsible for the development of flowers. Three gene activities interact in a combinatorial manner to determine the developmental identities of the primordia organ within the floral apical meristem . These gene functions are called A, B, and C. Genes are expressed in only the outer and lower most section of
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