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 defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was 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. Viruses are a special case, driven by a balance of mutation and selection, 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 formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. 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, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, 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 is a group of sexually reproducing organisms that recognize 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. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds 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 the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Hardiness of plants describes their ability to survive adverse growing conditions. It is limited to discussions of climatic adversity, thus a plant's ability to tolerate cold, drought, flooding, or wind are considered measurements of hardiness. Hardiness of plants is defined by their native extent's geographic location: longitude and elevation; these attributes are simplified to a hardiness zone. In temperate latitudes, the term most describes resistance to cold, or "cold-hardiness", is measured by the lowest temperature a plant can withstand. Hardiness of a plant is divided into two categories: tender, hardy; some sources use the erroneous terms "Half-hardy" or "Fully hardy". Tender plants are those killed by freezing temperatures, while hardy plants survive freezing—at least down to certain temperatures, depending on the plant. "Half-hardy" is a term used sometimes in horticulture to describe bedding plants which are sown in heat in winter or early spring, planted outside after all danger of frost has passed.
"Fully hardy" refers to plants being classified under the Royal Horticultural Society classifications, can cause confusion to those not using this method. Plants vary a lot in their tolerance of growing conditions; the selective breeding of varieties capable of withstanding particular climates forms an important part of agriculture and horticulture. Plants adapt to changes in climate on their own to some extent. Part of the work of nursery growers of plants consists of cold hardening, or hardening off their plants, to prepare them for conditions in life. Winter-hardy plants grow during the winter, or at least remain dormant. Apart from hardy evergreens, these include many cultivated plants, including varieties of cabbage and broccoli, all kinds of carrot; some bulbs – such as tulips – need cold winters to bloom, while others – such as freesia – can survive a freezing winter. Many domestic plants are assigned a hardiness zone that specifies the climates in which they can survive. Winter gardens are dependent upon the cultivation of winter-hardy plants.
Woody plants survive freezing temperatures by suppressing the formation of ice in living cells or by allowing water to freeze in plant parts that are not affected by ice formation. The common mechanism for woody plants to survive up to –40 °C is supercooling. Woody plants that survive lower temperatures are dehydrating their cells, allowing water to freeze between cell walls and the cells to survive. Plants considered hardy may not survive freezing if they are not acclimated, which renders them unable to use these mechanisms. Various hardiness ratings are published. In the USA, the most used is the USDA system of hardiness zones based on average minimum yearly temperatures; this system was developed for the diverse range of conditions in the United States, from baking desert to frozen tundra. Another used system is the Sunset Climate Zone system; this system is less dependent on the yearly minimum. In contrast the United Kingdom and Western Europe have an oceanic climate, experience a narrower range of temperatures, tempered by the presence of the Gulf Stream.
This results in areas like western Scotland experiencing mild winter conditions that enable the growing of subtropical plants, despite being well to the north of subtropical climate areas. The Royal Horticultural Society has published a set of hardiness ratings applicable to the UK; the ratings range from H1a to H7. H1a, higher than 15 °C, applies to tropical plants permanently under glass in heat. Most outdoor plants in the UK fall within the range H4, −10 to −5 °C to H5, −15 to −10 °C; the average minimum temperature in the UK is much warmer than the average minimums in most of the US. This means that the coldest areas in the UK would be considered USDA Zone 7, plants considered'Fully Hardy' in the UK may not be hardy below Zone 7 in the US. In addition to cold tolerance, plant hardiness has been observed to be linked to how much stress specific plants are undergoing into the winter, or how fast the onset of cold weather is in a specific year; this means that stressed plants will exhibit less cold tolerance than plants that have been well maintained.
Plants may die if the winter changes from balmy to exceptionally cold in a short period of time. Hardiness zone Microclimate Interactive Version of the 1990 USDA Hardiness Zone Map
Native plants are plants indigenous to a given area in geologic time. This includes plants that have developed, occur or existed for many years in an area. An ecosystem consists of interactions of plants and microorganisms with their physical and climatic conditions. Native plants form plant communities and biological interactions with specific flora, fauna and other organisms. For example, some plant species can only reproduce with a continued mutualistic interaction with a certain animal pollinator, the pollinating animal may be dependent on that plant species for a food source; some native plants have adapted to limited, unusual, or harsh conditions, such as cold climates or frequent wildfires. Others can adapt well to different surroundings; the diversity of species across many parts of the world exists only because bioregions are separated by barriers large rivers, oceans and deserts. Humans can introduce species that have never met in their evolutionary history, on varying time scales ranging from days to decades.
Humans are moving species across the globe at an unprecedented rate. Those working to address invasive species view this as an increased risk to indigenous species; as humans introduce plants to new locations for cultivation, or transport them by accident, some of them may become invasive species, damaging native plant communities. Invasive species can have profound effects on ecosystems by changing ecosystem structure, species abundance, community composition. Besides ecological damage, these species can damage agriculture and cultural assets. Government agencies and environmental groups are directing increasing resources to addressing these species; when restoration projects are undertaken to restore a native ecological system disturbed by economic development or other events, they may be inaccurate, incomplete, or pay little or no attention to ecotype accuracy or type conversions. They may fail to restore the original ecological system by overlooking the basics of remediation. Attention paid to the historical distribution of native species is a crucial first step to ensure the ecological integrity of the project.
For example, to prevent erosion of the recontoured sand dunes at the western edge of the Los Angeles International Airport in 1975, landscapers stabilized the backdunes with a “natural” seed mix. The seed mix was representative of coastal sage scrub, an exogenous plant community, instead of the native dune scrub community; as a result, the El Segundo blue butterfly became an endangered species. The El Segundo Blue butterfly population, which had once extended over 3200 acres along the coastal dunes from to Ocean Park to Malaga cove in Palos Verdes, began to recover when the invasive California buckwheat was uprooted so that the butterflies' original native plant host, the dune buckwheat, could regain some of its lost habitat. Native plant organizations such as Wild Ones, native plant societies, Lady Bird Johnson Wildflower Center encourage the use of native plants in public spaces; the identification of local remnant natural areas provides a basis for their work. The use of native cultivars is a disputed practice among native plant advocates.
Returning Essential Wildflowers to America’s Landscapes: Project Milkweed, Xerces Society Milkweeds are the required host plants for caterpillars of the monarch butterfly. Mary M. Walker, "Native Plant Societies of the United States and Canada" Long, John L. 1981. Introduced birds of the world: The worldwide history and influence of birds introduced to new environments. New York, Universe Books, New York City. Noah's Garden: Restoring the Ecology of Our Own Back Yards. Houghton-Mifflin. Vermeij, Geerat J. 1991. When biotas meet: Understanding biotic interchange. Science, 253:1099-1104 "About Native Plants", from the Dorothy King Chapter of the California Native Plant Society
Herbaceous plants are plants that have no persistent woody stem above ground. The term is applied to perennials, but in botany it may refer to annuals or biennials, include both forbs and graminoids. Annual herbaceous plants die at the end of the growing season or when they have flowered and fruited, they grow again from seed. Herbaceous perennial and biennial plants may have stems that die at the end of the growing season, but parts of the plant survive under or close to the ground from season to season. New growth develops from living tissues remaining on or under the ground, including roots, a caudex or various types of underground stems, such as bulbs, stolons and tubers. Examples of herbaceous biennials include carrot and common ragwort. By contrast, non-herbaceous perennial plants are woody plants which have stems above ground that remain alive during the dormant season and grow shoots the next year from the above-ground parts – these include trees and vines; some fast-growing herbaceous plants are pioneers, or early-successional species.
Others form the main vegetation of many stable habitats, occurring for example in the ground layer of forests, or in open habitats such as meadow, salt marsh or desert. Some herbaceous plants can grow rather large, such as the genus Musa; the age of some herbaceous perennial plants can be determined by herbchronology, the analysis of annual growth rings in the secondary root xylem
Ranunculales is an order of flowering plants. Of necessity it contains the family Ranunculaceae, the buttercup family, because the name of the order is based on the name of a genus in that family. Ranunculales belongs to a paraphyletic group known as the basal eudicots, it is the most basal clade in this group. Known members include poppies and buttercups; the term Ranales was used to include the Ranunculaceae and related families, as described by Bentham and Hooker. This became replaced with Ranunculales by Melchior in 1964; the Cronquist system recognised the order, but placed it in the subclass Magnoliidae, in class Magnoliopsida. It used this circumscription: order Ranunculales family Ranunculaceae family Circaeasteraceae family Berberidaceae family Sargentodoxaceae family Lardizabalaceae family Menispermaceae family Coriariaceae family SabiaceaeIn the Cronquist system, the Papaveraceae and Fumariaceae were treated as a separate order Papaverales, placed in this same subclass Magnoliidae; the Cronquist circumscription of Ranunculales is now known to be polyphyletic.
Sabiaceae is in a clade of basal eudicots separate from Ranunculales. Coriariaceae is now placed in the order Cucurbitales; the Angiosperm Phylogeny Group recognized seven families in Ranunculales in their APG III system, published in 2009. In the preceding APG II system, they offered the option of three segregate families. Order Ranunculales family Berberidaceae family Circaeasteraceae family Eupteleaceae family Lardizabalaceae family Menispermaceae family Papaveraceae family RanunculaceaeNote: "+..." = optionally separate family. Under this definition, well-known members of Ranunculales include buttercups, columbines and poppies. A phylogeny of Ranunculales was published in 2009, based on molecular phylogenetic analysis of DNA sequences; the authors of this paper revised the tribes of the order. This is reflected in the subsequent revision of the APG, APG IV; the analysis revealed that the order consisted of three clades, Papaveraceae and a third clade, considered to be the "core" Ranuculales, consisting of the remaining five families.
The phylogeny of the families is shown in the cladogram. The fossil form Leefructus, described in 2011, has been recognized as a member of this order. Leefructus mirus shows developed leaves; the fossil is dated to 125 million years old and it not only proves that Ranunculales is an ancient group of eudicots but demonstrates that the whole angiosperm clade may be older than expected. The structure of the plant and its age may lead to a new approach regarding the field that studies the evolution of flowering plants; the fact that Leefructus shows a well-developed structure similar to modern ranunculids suggests that this group of eudicots may have developed earlier than the age of the fossil. NCBI Taxonomy Browser
Ranunculaceae is a family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide. The largest genera are Ranunculus, Thalictrum and Aconitum. Ranunculaceae are herbaceous annuals or perennials, but some woody climbers or shrubs. Most members of the family have bisexual flowers which can be inconspicuous. Flowers may be solitary, but are found aggregated in cymes, panicles, or spikes; the flowers are radially symmetrical but are bilaterally symmetrical in the genera Aconitum and Delphinium. The sepals, petals and carpels are all free, the outer flower segments number four or five; the outer stamens may be modified to produce only nectar, as in Delphinium. In some genera, such as Thalictrum the sepals are colorful and appear petal-like and the petals can be inconspicuous or absent; the stems are unarmed. The leaves are variable. Most species have both basal and cauline leaves, which are compound or lobed but can be simple, they are alternate, or opposite or whorled. Many species the perennials form rhizomes that develop new roots each year.
Ficaria verna can reproduce vegetatively by means of root tubers produced in the leaf axils. Some members of the genus Thalictrum utilize anemophily. Flowers of the entomophilous genus Papaver of the Ranunculales order, produce only pollen; until it was believed that the species of the genus Anemone lack nectar. The fruits are most free, unfused achenes or follicles, but a berry in Actaea. Ranunculaceae contain protoanemonin, toxic to humans and animals. Other poisonous or toxic compounds and glycosides, are common. Takhtajan included the Ranunculaceae as the only family in the Ranunculales which he placed in a subclass, the Ranunculidae, instead of a superorder. Thorn placed the Ranunculaceae in the Berberidales, an order within the Superorder Magnolianae. Earlier Cronquist in 1981 included the Ranunculaceae along with seven other families in the Rancunculales, included in the Magnoliidae, which he regarded as a subclass. David, placed the Ranuculaceae, together with the Eupteleaceae, Menispermaceae and Papaveraceae in the Ranunculales, the only order in the superorder Ranunculanae.
This follows the work of the Angiosperm Phylogeny Group. The family Ranunculaceae sensu stricto is one of seven families included in the order Ranunculales within the eudicots according to the Angiosperm Phylogeny Group classification; the family is monophyletic with Glaucidium as sister to the remaining genera. This phylogeny is illustrated in the APG Poster. Early subdivisions of the family, such as Adanson divided it based on one-seeded or many-seeded fruit. Prantl envisaged three tribes, Paeonieae and Anemoneae with Paeonia and Hydrastis forming Paeoniaae. By the twentieth century Langlet used chromosome types to create two subfamilies and Thalictroideae. In 1966 Tamura further developed Langlet's system by adding floral characteristics with six subfamilies. Paeonia was placed in its own family of Paeoniaceae. Other genera included in Ranunculaceae include Circaeaster, placed in its own family Circaeasteraceae. Tamura's complete system was structured. Adonideae Kunth Anemoneae DC. Ranunculeae DC.
Subfamily Helleboroideae Hutch. Helleboreae DC. Cimicifugeae Torrey & A. Gray Delphineae Schrödinger Nigelleae Schrödinger Subfamily Isopyroideae Tamura Coptideae Langlet ex Tamura & K. Kosuge Dichocarpeae Tamura & K. Kosuge Isopyreae Schrödinger Subfamily Thalictroideae Subfamily HydrastidoideaeThe genus Glaucidium, having been moved to its own family, has since been restored to Ranuculaceae; when subjected to molecular phylogenetic analysis only Thalictroideae is monophyletic. The position of Glaucidium and some of its unique morphological characteristics prompted Stevens to suggest that it be given subfamilial rank as the monotypic Glaucidioideae. Hydrastis has been assigned to subfamily Hydrastidoideae. Both genera are represented by a single species, Glaucidium palmatum and Hydrastis canadense respectively; the relationships between the genera suggest the existence of three major clades corresponding to Coptidoideae and Ranunculoideae. The latter is the largest with four subclades. Of these C corresponds to D to Cimicifugae and E to Ranunculoideae.
Wang and colleagues proposed a new classification with five subfamilies, further subdividing Ranunculoideae into ten tribes. The relationship between the subfamilies is shown in the cladogram; the other genera belong to Ranunculoideae. Kingdonia had been included by Tamura in Anemoneae, but is now added
Pulsatilla patens is a species of flowering plant in the family Ranunculaceae, native to Europe, Mongolia, China and the United States. Common names include Eastern pasqueflower, prairie crocus, cutleaf anemone. Pulsatilla patens is placed in the genus Anemone, as Anemone patens L.. Pulsatilla patens is the provincial flower of Manitoba, Canada and is the state flower of South Dakota, United States, it is the regional flower of the region of Tavastia Proper in Finland. Advocates report that the population of Pulsatilla patens is declining, due to the synergy between the prairie crocus and shortgrass prairie ecosystems. Plowing up the prairie causes the crocus to disappear. Two subspecies have been distinguished: Pulsatilla patens subsp. Patens Pulsatilla patens subsp. Multifida Zämelis—cutleaf anemone Data related to Pulsatilla patens at Wikispecies Media related to Anemone patens at Wikimedia Commons