The Angiosperm Phylogeny Group is an international group of systematic botanists who have come together to try to establish a consensus view of the taxonomy of flowering plants in the light of the rapid rise of molecular systematics. Botany is the scientific study of plantlife. ... Taxonomy (from Greek verb tassein = to classify and nomos = law, science, cf economy) may refer to: the science of classifying living things (see alpha taxonomy) a classification Initially, taxonomy was only the science of classifying living organisms, but later the word was applied in a wider sense, and may also... Classes Magnoliopsida- Dicots Liliopsida- Monocots The flowering plants (also called angiosperms) are a major group of land plants. ... Molecular systematics is a product of the traditional field of systematics and the growing field of bioinformatics. ...

The flowering plants (also known as angiosperms, Angiospermae, Anthophyta, Magnoliophyta), are one of the groups of organisms whose classification has been affected most radically as molecular data became available. The influential classification scheme published by American botanist Arthur Cronquist in 1981, the Cronquist system, had been increasingly challenged during the 1990s. The molecular data that have become available since around 1990, analysed by cladistic methods, have clarified our views of some relationships and radically changed others. This has made possible a much closer approach to the phylogenetic goal of making classification reflect descent. Arthur C. Cronquist (1919–1992) was a North American botanist who wrote An Integrated System of Classification of Flowering Plants (1981) and The Evolution and Classification of Flowering Plants (1988). ... The Cronquist system is a scheme for the classification of flowering plants (or angiosperms). ... This cladogram shows the relationship among various insect groups. ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ...

The rapid increase in knowledge has led to many proposed changes in classifications, and these pose problems for all users of classifications (including encyclopaedists). By bringing together researchers from major institutions world-wide, and publishing jointly, the Angiosperm Phylogeny Group have sought to provide a stable point of reference, publishing the APG-system (1998). This system deals mostly with higher ranks and, as there are still severe limits to our knowledge, a firm classification is not possible in all cases.

The system is based on two chloroplast genes and one gene coding for ribosomes. This selection of genes from cell organelles is significant; zoological taxonomy similarly uses genes of mitochondria. The genome of cell organelles is separated somewhat from the nuclear genome, both chloroplasts and mitochondria having their own DNA, actually prokaryote DNA. The sequence of nucleotides is subject to a different rate of change compared to nuclear DNA. The inside of a chloroplast Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Schematic of typical animal cell, showing subcellular components. ... Mitochondria structure : 1) Inner membrane 2) Outer membrane 3) Crista 4) Matrix In cell biology, a mitochondrion (plural mitochondria) (from Greek mitos thread + khondrion granule) is an organelle found in most eukaryotic cells. ...

The first APG classification was published in 1998; a revised version was published in 2003 (APG, 2003), and is known as APG II 2003 or just APG II. Its major innovations were:

• Not to use formal, scientific names above the level of order, but rather to have named clades, such as eudicots, monocots and rosids.
• To place a substantial number of taxa whose classification has traditionally been uncertain.
• To offer alternative classifications for some groups, in which for example a number of families can either be regarded as separate or can be merged into a single larger family. APG II refers to such groups as "bracketed" taxa.

Bracketed taxa are introduced to help cope with the transition from the older, morphologically based classifications to the newer, molecularly-based systems, since the process has tended to produce a number of rather small taxa, e.g. monogeneric families, which are inconvenient for users. As the APG authors note (p. 402), "We generally accept the opinion of specialists... but we also recognise that specialists nearly always favour splitting of groups...". In the APG-system, the names eudicots or tricolpates are applied to a monophyletic group that includes most of the (former) dicotyledons. ... Orders Base Monocots: Acorus Alismatales Asparagales Dioscoreales Liliales Pandanales Family Petrosaviaceae Commelinids: Arecales Commelinales Poales Zingiberales Family Dasypogonaceae Monocotyledons or monocots are a group of flowering plants usually ranked as a class and once called the Monocotyledoneae. ...

Independent researchers, including members of the APG, continue to publish their own views on areas of angiosperm taxonomy, and in any case no classification is ever final; it presents a view at a particular point in time, based on a particular state of research. New results are always appearing. Nonetheless the APG publications are increasingly regarded as an authoritative point of reference.

Institutions represented among the principal authors of the APG II classification include:

• Royal Swedish Academy of Sciences
• Uppsala University, Sweden
• Royal Botanic Gardens, Kew, United Kingdom
• University of Maryland, College Park, USA
• University of Florida, Gainsville, USA
• Missouri Botanical Garden, USA

Contributions also came from many other institutions world-wide. The Royal Swedish Academy of Sciences or , founded in 1739 by King Frederick I, is one of the Royal Academies in Sweden. ... Uppsala University (Swedish Uppsala universitet) is a public university in Uppsala, Sweden. ... The Royal Botanic Gardens, Kew, usually referred to simply as Kew Gardens, are extensive gardens and botanical glasshouses between Richmond upon Thames and Kew in southwest London, England. ... The University of Maryland, College Park (also known as UM, UMD, or UMCP) is a public university located in College Park, Maryland, just outside Washington, D.C., USA. As the flagship institution of the University System of Maryland, the university is most often referred to as the University of Maryland... University of Florida State University System of Florida FAMU FAU FGCU FIU FSU NCF UCF UF UNF USF UWF The University of Florida is a public university and land-grant institution located in Gainesville, Florida. ... Categories: US geography stubs | Botanical gardens | Missouri landmarks | Saint Louis, Missouri ...

References

• Angiosperm Phylogeny Group (2003). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399-436 (Available online: Abstract | Full text (HTML) | Full text (PDF)).