The Zygophyllales are an order of dicotyledonous plants, comprising the following two families: Family Zygophyllaceae Family KrameriaceaeAccording to the Angiosperm Phylogeny Group both families are unplaced to order, but included in the Eurosids I. The APG III system of 2009, recognized this order. If the monogeneric family Krameriaceae shares little common traits with the family Zygophyllaceae, researchers see little advantage in keeping it as a separate family; the name Zygophyllales can be used. The order keeps unchanged in the APG IV system. Under the Cronquist system, the Zygophyllaceae were included within the Sapindales, the Krameriaceae within the Polygalales
Armen Leonovich Takhtajan or Takhtajian, was a Soviet-Armenian botanist, one of the most important figures in 20th century plant evolution and systematics and biogeography. His other interests included morphology of flowering plants and the flora of the Caucasus, he was born in Shusha. He was one of the most influential taxonomists of the latter twentieth century. Takhtajan was born in Shusha, Russian Empire, present-day Azerbaijan on 10 June 1910, to a family of Armenian intellectuals, his grandfather Meliksan Takhtadzhyan Petrovich had been born in Trabzon, Ottoman Empire and was educated in Italy, on the island of San Lazzaro degli Armeni, an Armenian enclave, spoke many languages and worked as a journalist. He died in Paris in 1930, his father, Leon Meliksanovich Takhtadzhyan, was born in Batumi and was educated as an agronomist at Leipzig University. Graduating in 1906, he worked on farms in France and the United Kingdom, made a special study of sheep farming, he became proficient in German, English, Russian and Azerbaijani.
Arriving in Shusha in 1908 a centre of sheep farming in the Caucasus, looking for work, Leon was forced to teach German at the local Realschule attached to the Armenian seminary, due to lack of opportunities in his chosen field. There he met and married Gerseliya Sergeevna Gazarbekyan, Armen Takhtajan's mother, a native of Susha, in 1909; the Takhtajans had three children, Armen and Nora. In 1918 the family were forced to flee to northern Armenia because of the pogroms. Throughout his childhood, Armen showed a keen interest in natural history, travelling with his father. Armen attended school in Tbilisi in nearby Georgia at Unified Labor School number 42. There he came under the influence of one of his teachers, Alexander Konstantinovich Makaev, who had taught agriculture at Tbilisi State University, had produced a dictionary of botanical names in Georgian and Latin. Makaev would take Armen on botanical excursions, teaching him to identify plants from Sosnowski and Grossheim's "Determinants of plant life in the vicinity of Tbilisi".
In 1928 he travelled to Leningrad. There he volunteered at the biology school at Leningrad University and attended lectures by Vladimir Leontyevich Komarov on plant morphology. In 1929 he began his studies in biology at Yerevan State University in Yerevan, which he completed in 1931, he returned to Tbilisi, enrolling in the All-Union Institute of Subtropical Crops. In 1932 after completing his course at Tbilisi he worked for a while as a laboratory assistant at Sukhumi, Georgia, at the subtropical branch of the All-Union Institute of Applied Botany and New Crops, before returning to Yerevan. In Yerevan he took a position as researcher at the Natural History Museum of Armenia, at the Herbarium of the Armenian branch of the Institute of Biology, Soviet Academy of Sciences, began teaching at Yerevan University in 1936, while completing his Master's thesis, he died in Saint Petersburg on November 13, 2009, at the age of 99, in 2009, having just completed his most important work, Flowering Plants.
From 1938-48 he headed a Department at the Yerevan State University, from 1944-48 was director of the Botanical Institute of the Academy of Sciences of the Armenian SSR, Professor of the Leningrad State University. Takhtajan was a member of the Russian Academy of Sciences, as well as a foreign associate of the U. S. National Academy of Sciences since 1971, he was the academician of the Academy of Sciences of the Armenian SSR, the president of the Soviet All-Union Botanical Society and the International Association for Plant Taxonomy, member of the Finnish Academy of Science and Literature, the German Academy of Naturalists "Leopoldina" and other scientific societies. While at the Komarov Botanical Institute in Leningrad in 1940, Takhtajan developed his classification scheme for flowering plants, which emphasized phylogenetic relationships between plants, his system did not become known to botanists in the West until after 1950, in the late 1950s he began a correspondence and collaboration with the prominent American botanist Arthur Cronquist, whose plant classification scheme was influenced by his collaboration with Takhtajan and other botanists at Komarov.
He is chiefly famous as the author of works on the origins of flowering plants and paleobotany, developing a new classification system of higher plants. He worked on the "Flora of Armenia" and "Fossil flowering plants of the USSR " books. Takhtajan developed a system of floristic regions. For many years restrictions were placed on his work because of his opposition to the official line on genetics promoted by Lysenko. In 1993 he worked for a while at the New York Botanical Garden; the "Takhtajan system" of flowering plant classification treats flowering plants as a division, with two classes and Liliopsida. These two classes are subdivided into subclasses, superorders and families; the Takhtajan system is similar to the Cronquist system, but with somewhat greater complexity at the higher levels. He favors smaller orders and families, to allow character and evolutionary relationships to be more grasped; the Takhtajan classification system rema
International Code of Nomenclature for algae, fungi, and plants
The International Code of Nomenclature for algae and plants is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "traditionally treated as algae, fungi, or plants". It was called the International Code of Botanical Nomenclature; the current version of the code is the Shenzhen Code adopted by the International Botanical Congress held in Shenzhen, China, in July 2017. As with previous codes, it took effect as soon as it was ratified by the congress, but the documentation of the code in its final form was not published until 26 June 2018; the name of the Code is capitalized and not. The lower-case for "algae and plants" indicates that these terms are not formal names of clades, but indicate groups of organisms that were known by these names and traditionally studied by phycologists and botanists; this includes blue-green algae. There are special provisions in the ICN for some of these groups.
The ICN can only be changed by an International Botanical Congress, with the International Association for Plant Taxonomy providing the supporting infrastructure. Each new edition supersedes the earlier editions and is retroactive back to 1753, except where different starting dates are specified. For the naming of cultivated plants there is a separate code, the International Code of Nomenclature for Cultivated Plants, which gives rules and recommendations that supplement the ICN. Botanical nomenclature is independent of zoological and viral nomenclature. A botanical name is fixed to a taxon by a type; this is invariably dried plant material and is deposited and preserved in a herbarium, although it may be an image or a preserved culture. Some type collections can be viewed online at the websites of the herbaria in question. A guiding principle in botanical nomenclature is priority, the first publication of a name for a taxon; the formal starting date for purposes of priority is 1 May 1753, the publication of Species Plantarum by Linnaeus.
However, to avoid undesirable effects of strict enforcement of priority, conservation of family and species names is possible. The intent of the Code is that each taxonomic group of plants has only one correct name, accepted worldwide, provided that it has the same circumscription and rank; the value of a scientific name is. Names of taxa are treated as Latin; the rules of nomenclature are retroactive unless there is an explicit statement that this does not apply. The rules governing botanical nomenclature have a long and tumultuous history, dating back to dissatisfaction with rules that were established in 1843 to govern zoological nomenclature; the first set of international rules was the Lois de la nomenclature botanique, adopted as the "best guide to follow for botanical nomenclature" at an "International Botanical Congress" convened in Paris in 1867. Unlike modern codes, it was not enforced, it was organized as six sections with 68 articles in total. Multiple attempts to bring more "expedient" or more equitable practice to botanical nomenclature resulted in several competing codes, which reached a compromise with the 1930 congress.
In the meantime, the second edition of the international rules followed the Vienna congress in 1905. These rules were published as the Règles internationales de la Nomenclature botanique adoptées par le Congrès International de Botanique de Vienne 1905. Informally they are referred to as the Vienna Rules; some but not all subsequent meetings of the International Botanical Congress have produced revised versions of these Rules called the International Code of Botanical Nomenclature, International Code of Nomenclature for algae and plants. The Nomenclature Section of the 18th International Botanical Congress in Melbourne, Australia made major changes: The Code now permits electronic-only publication of names of new taxa; the requirement for a Latin validating diagnosis or description was changed to allow either English or Latin for these essential components of the publication of a new name. "One fungus, one name" and "one fossil, one name" are important changes. As an experiment with "registration of names", new fungal descriptions require the use of an identifier from "a recognized repository".
Some important versions are listed below. Specific to botany Author citation Botanical name Botanical nomenclature International Association for Plant Taxonomy International Code of Nomenclature for Cultivated Plants International Plant Names Index Correct name Infraspecific name Hybrid name More general Glossary of scientific naming Binomial nomenclature Nomenclature codes Scientific classification Undescribed species
The Vitaceae are a family of dicotyledonous flowering plants, with 14 genera and ca 910 known species, including the grapevine and Virginia creeper. The family name is derived from the genus Vitis; the name sometimes appears as Vitidaceae, but Vitaceae is a conserved name and therefore has priority over both Vitidaceae and another name sometimes found in the older literature, Ampelidaceae. In the APG III system onwards, the family is placed in Vitales. Molecular phylogenetic studies place the Vitales as the most basal clade in the rosids. In the Cronquist system, the family was placed near the family Rhamnaceae in order Rhamnales. Most Vitis species have 38 chromosomes, but 40 in subgenus Muscadinia, while Ampelocissus and Ampelopsis have 40 chromosomes and Cissus has 24 chromosomes; the family is economically important as the berries of Vitis species known as grapes, are an important fruit crop and, when fermented, produce wine. Species of the genus Tetrastigma serve as hosts to parasitic plants in the family Rafflesiaceae.
Leea, sometimes classified in its own family, Leeaceae, is included in Vitaceae by APG IV and the Angiosperm Phylogeny Website. Well preserved-fruits of Indovitis chitaleyae containing seeds with similar morphology to the Vitaceae have been recovered from Late Cretaceous Deccan Intertrappean beds of several sites in central India; these fruits and their dispersed seeds found in the same sediments, about 66 million years old, represent the oldest known fossils of the grape family. The fossil fruits containing 4 to 6 seeds are similar to extant Vitis
The flowering plants known as angiosperms, Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 64 orders, 416 families 13,164 known genera and c. 369,000 known species. Like gymnosperms, angiosperms are seed-producing plants. However, they are distinguished from gymnosperms by characteristics including flowers, endosperm within the seeds, the production of fruits that contain the seeds. Etymologically, angiosperm means a plant; the term comes from the Greek words sperma. The ancestors of flowering plants diverged from gymnosperms in the Triassic Period, 245 to 202 million years ago, the first flowering plants are known from 160 mya, they diversified extensively during the Early Cretaceous, became widespread by 120 mya, replaced conifers as the dominant trees from 100 to 60 mya. Angiosperms differ from other seed plants in several ways, described in the table below; these distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans.
Angiosperm stems are made up of seven layers. The amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms; the vascular bundles of the stem are arranged such that the phloem form concentric rings. In the dicotyledons, the bundles in the young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium. By the formation of a layer of cambium between the bundles, a complete ring is formed, a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside; the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth, called annual rings.
Among the monocotyledons, the bundles are more numerous in the young stem and are scattered through the ground tissue. They once formed the stem increases in diameter only in exceptional cases; the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, provide the most trustworthy external characteristics for establishing relationships among angiosperm species; the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally from the axil of a leaf; as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. More the flower-bearing portion of the plant is distinguished from the foliage-bearing or vegetative portion, forms a more or less elaborate branch-system called an inflorescence. There are two kinds of reproductive cells produced by flowers. Microspores, which will divide to become pollen grains, are the "male" cells and are borne in the stamens.
The "female" cells called megaspores, which will divide to become the egg cell, are contained in the ovule and enclosed in the carpel. The flower may consist only of these parts, as in willow, where each flower comprises only a few stamens or two carpels. Other structures are present and serve to protect the sporophylls and to form an envelope attractive to pollinators; the individual members of these surrounding structures are known as petals. The outer series is green and leaf-like, functions to protect the rest of the flower the bud; the inner series is, in general, white or brightly colored, is more delicate in structure. It functions to attract bird pollinators. Attraction is effected by color and nectar, which may be secreted in some part of the flower; the characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans. While the majority of flowers are perfect or hermaphrodite, flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization.
Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot transfer pollen to the pistil. Homomorphic flowers may employ a biochemical mechanism called self-incompatibility to discriminate between self and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers; the botanical term "Angiosperm", from the Ancient Greek αγγείον, angeíon and σπέρμα, was coined in the form Angiospermae by Paul Hermann in 1690, as the name of one of his primary divisions of the plant kingdom. This included flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked; the term and its antonym were maintained by Carl Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any
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
The Saxifragales are an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system; some authors define the rosids more including Saxifragales as their most basal group. Saxifragales is one of the eight groups; the others are Gunnerales, Rosids, Berberidopsidales and Asterids. Saxifragales have an extensive fossil record; the extant members are remnants of a diverse and widespread order. The Saxifragales order, as it is now understood, is based upon the results of molecular phylogenetic studies of DNA sequences, it is not part of any of the classification systems based on plant morphology. The group is much in need of comparative anatomical study in light of the recent expansion of the family Peridiscaceae to include Medusandra, a genus that before 2009 had not been placed in Saxifragales; the order is divided into suprafamilial groups. These groups are not understood to have any particular taxonomic rank.
Saxifragales contain about 2470 species. These are distributed into 15 families, or into 12 families if Haloragaceae sensu lato is recognized as a family consisting of Haloragaceae sensu stricto, Penthorum and Aphanopetalum. About 95% of the species are in five families: Crassulaceae, Grossulariaceae and Hamamelidaceae. Most of the families are monogeneric; the number of genera in each family is: Some authors do not recognize Choristylis as a separate genus from Itea. Some authors sink Liquidambar and Semiliquidambar into Altingia, thus Altingiaceae and Iteaceae are monogeneric in some classifications. Within the Saxifragales is a suprafamilial group known as the Saxifragaceae alliance, it comprises four families: Pterostemonaceae, Iteaceae and Saxifragaceae. These have long been known to be related to each other, but the circumscription of Saxifragaceae has changed dramatically, it is now a much smaller family. Crassulaceae and Tetracarpaeaceae have long been associated with Saxifragaceae. Penthorum has been associated with Crassulaceae, but sometimes with Saxifragaceae.
Two members of the core Saxifragales had sometimes been placed near Saxifragaceae, but elsewhere. Aphanopetalum was placed in Cunoniaceae, a family in Oxalidales though there were good reasons to put it in Saxifragales. Aphanopetalum is now excluded from Cunoniaceae. Haloragaceae was thought to be a family in Myrtales, but it is no longer included in that order. Cercidiphyllaceae had for a long time been associated with Hamamelidaceae and Trochodendraceae and was thought to be closer to the latter. Cercidiphyllaceae is now known to be a member of the woody clade of Saxifragales, along with Hamamelidaceae and Daphniphyllaceae, but Trochodendraceae is in the basal eudicot order Trochodendrales. Altingiaceae was not separated from Hamamelidaceae until phylogenetic studies showed that its inclusion might make Hamamelidaceae paraphyletic; the recognition of Altingiaceae as a separate family received strong statistical support in 2008. Daphniphyllum was always thought to have an anomalous combination of characters and it was placed in several different orders before molecular phylogenetic analysis showed it to belong to Saxifragales.
Paeoniaceae possesses many unique features and its taxonomic position was for a long time controversial. The idea has long persisted. Paeoniaceae has been shown unequivocally to belong in Saxifragales, while Glaucidium is in the family Ranunculaceae; the family Peridiscaceae underwent radical shifting and recircumscription from 2003 to 2009. It consisted of two related genera and Whittonia; the APG II system placed the family in Malpighiales, based on a DNA sequence for the rbcL gene from Whittonia. This sequence turned out to be not from Whittonia, but from other plants whose DNA had contaminated the sample. After Peridiscaceae was placed in Saxifragales, it was expanded to include Soyauxia in 2007, expanded again to include Medusandra in 2009; the phylogeny shown below is based on the one published by Shuguang Jian and coauthors in 2008. All branches have 100% maximum likelihood bootstrap support except where labeled with bootstrap percentage. Monogeneric families are represented by genus names.
Plant order classification at: Saxifragales Trees At: Angiosperm Phylogeny Website At: Missoure Botanical Garden Website Saxifragales At: Angiosperm Phylogeny Website Wurdack, Kenneth J.. "Malpighiales phylogenetics: Gaining ground on one of the most recalcitrant clades in the angiosperm tree of life". American Journal of Botany. 96: 1551–70. Doi:10.3732/ajb.0800207. PMID 21628300. Jian, Shuguang. "Resolving an ancient, rapid radiation in Saxifragales". Systematic Biology. 57: 38–57. Doi:10.1080/10635150801888871. PMID 18275001. Kubitzki, Klaus, ed.. Flowering Plants. Eudicots: Berberidopsidales, Crossosomatales, Fabales p.p. Geraniales, Myrtales p.p. Proteales, Vitales, Clusiaceae Alliance, Passifloraceae Alliance, Huaceae, Sabiaceae; the Families and Genera of Vascular Plants. IX. Springer. ISBN 978-3-540-32219-1