Plants are multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. Plants were treated as one of two kingdoms including all living things that were not animals, all algae and fungi were treated as plants. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes. By one definition, plants form the clade Viridiplantae, a group that includes the flowering plants and other gymnosperms and their allies, liverworts and the green algae, but excludes the red and brown algae. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria, their chloroplasts contain b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is common.
There are about 320 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants. Green plants provide a substantial proportion of the world's molecular oxygen and are the basis of most of Earth's ecosystems on land. Plants that produce grain and vegetables form humankind's basic foods, have been domesticated for millennia. Plants have many cultural and other uses, as ornaments, building materials, writing material and, in great variety, they have been the source of medicines and psychoactive drugs; the scientific study of plants is known as a branch of biology. All living things were traditionally placed into one of two groups and animals; this classification may date from Aristotle, who made the distincton between plants, which do not move, animals, which are mobile to catch their food. Much when Linnaeus created the basis of the modern system of scientific classification, these two groups became the kingdoms Vegetabilia and Animalia. Since it has become clear that the plant kingdom as defined included several unrelated groups, the fungi and several groups of algae were removed to new kingdoms.
However, these organisms are still considered plants in popular contexts. The term "plant" implies the possession of the following traits multicellularity, possession of cell walls containing cellulose and the ability to carry out photosynthesis with primary chloroplasts; when the name Plantae or plant is applied to a specific group of organisms or taxon, it refers to one of four concepts. From least to most inclusive, these four groupings are: Another way of looking at the relationships between the different groups that have been called "plants" is through a cladogram, which shows their evolutionary relationships; these are not yet settled, but one accepted relationship between the three groups described above is shown below. Those which have been called "plants" are in bold; the way in which the groups of green algae are combined and named varies between authors. Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom.
The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the green algae, red algae and brown algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, they are no longer classified as plants as defined here; the Viridiplantae, the green plants – green algae and land plants – form a clade, a group consisting of all the descendants of a common ancestor. With a few exceptions, the green plants have the following features in common, they undergo closed mitosis without centrioles, have mitochondria with flat cristae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. Two additional groups, the Rhodophyta and Glaucophyta have primary chloroplasts that appear to be derived directly from endosymbiotic cyanobacteria, although they differ from Viridiplantae in the pigments which are used in photosynthesis and so are different in colour.
These groups differ from green plants in that the storage polysaccharide is floridean starch and is stored in the cytoplasm rather than in the plastids. They appear to have had a common origin with Viridiplantae and the three groups form the clade Archaeplastida, whose name implies that their chloroplasts were derived from a single ancient endosymbiotic event; this is the broadest modern definition of the term'plant'. In contrast, most other algae not only have different pigments but have chloroplasts with three or four surrounding membranes, they are not close relatives of the Archaeplastida having acquired chloroplasts separately from ingested or symbiotic green and red algae. They are thus not included in the broadest modern definition of the plant kingdom, although they were in the past; the green plants or Viridiplantae were traditionally divided into the green algae (including
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
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
Urtica dioica known as common nettle, stinging nettle or nettle leaf, or just a nettle or stinger, is a herbaceous perennial flowering plant in the family Urticaceae. Native to Europe, much of temperate Asia and western North Africa, it is now found worldwide; the species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation upon contact. The plant has a long history of use as a source for traditional medicine, food and textile raw material in ancient societies. Urtica dioica is a dioecious, perennial plant, 1 to 2 m tall in the summer and dying down to the ground in winter, it has spreading rhizomes and stolons, which are bright yellow, as are the roots. The soft, green leaves are 3 to 15 cm long and are borne oppositely on an erect, green stem; the leaves have a serrated margin, a cordate base, an acuminate tip with a terminal leaf tooth longer than adjacent laterals.
It bears small, numerous flowers in dense axillary inflorescences. The leaves and stems are hairy with non-stinging hairs, in most subspecies bear many stinging hairs, whose tips come off when touched, transforming the hair into a needle that can inject several chemicals causing a painful sting or paresthesia, giving the species its common names: stinging nettle, burn nettle, burn weed, or burn hazel; the taxonomy of Urtica species has been confused, older sources are to use a variety of systematic names for these plants. More species were recognised than are now accepted. However, at least six clear subspecies of U. dioica are described, some classified as separate species: U. dioica subsp. Dioica, from Europe and northern Africa, has stinging hairs. U. dioica subsp. Galeopsifolia, from Europe, does not have stinging hairs. U. dioica subsp. Afghanica, from southwestern and central Asia, sometimes has stinging hairs or is sometimes hairless. U. dioica subsp. Gansuensis, from eastern Asia, has stinging hairs.
U. dioica subsp. Gracilis Selander, from North America, has stinging hairs. U. dioica subsp. Holosericea Thorne, from North America, has stinging hairs. Other species' names accepted as distinct by some authors but now regarded as synonyms of one or other subspecies include U. breweri, U. californica, U. cardiophylla, U. lyalli, U. major, U. procera, U. serra, U. strigosissima, U. trachycarpa, U. viridis. Urtica dioica is considered to be native to much of temperate Asia and western North Africa, it is abundant in northern Europe and much of Asia found in the countryside. It is less widespread in southern Europe and north Africa, where it is restricted by its need for moist soil, but is still common, it has been introduced to many other parts of the world. In North America, it is distributed in Canada and the United States, where it is found in every province and state except for Hawaii, can be found in northernmost Mexico, it grows in abundance in the Pacific Northwest in places where annual rainfall is high.
The European subspecies has been introduced into North America and South America. In Europe, nettles have a strong association with human habitation and buildings; the presence of nettles may indicate the site of a long-abandoned building, can indicate soil fertility. Human and animal waste may be responsible for elevated levels of phosphate and nitrogen in the soil, providing an ideal environment for nettles. Nettles are the exclusive larval food plant for several species of butterflies, such as the peacock butterfly and the small tortoiseshell, it is eaten by the larvae of some moths including angle shades, buff ermine, dot moth, the flame, the gothic, grey chi, grey pug, lesser broad-bordered yellow underwing, mouse moth, setaceous Hebrew character, small angle shades. The roots are sometimes eaten by the larva of the ghost moth Hepialus humuli. Stinging nettle is found as an understory plant in wetter environments, but it is found in meadows. Although nutritious, it is not eaten by either wildlife or livestock because of the sting.
It spreads by abundant seeds and by rhizomes, is able to survive and re-establish after fire. Urtica dioica produces its inflammatory effect on skin both by impaling the skin via spicules – causing mechanical irritation – and by biochemical irritants, such as histamine and choline, among other chemicals. Anti-itch drugs in the form of creams containing antihistamines or hydrocortisone, may provide relief from nettle dermatitis. In Great Britain, the use of dock leaves on nettle stings is an established folk remedy, revolves around the sap released from rubbing the leaf over affected areas of skin, which provides a cooling sensation. Docks and nettles grow in the vicinity of each other due to both plants favouring the same soil conditions, this may have aided the dock's popularity as a treatment for nettle stings; the term, contact urticaria, has a wider use in dermatology, involving dermatitis caused by various skin irritants and pathogens. In Great Britain and Ireland, the stinging nettle is the only common stinging plant and has found a place in several figures of speech in the English language.
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Salvia is the largest genus of plants in the mint family, with nearly 1000 species of shrubs, herbaceous perennials, annuals. Within the Lamiaceae, Salvia is part of the tribe Mentheae within the subfamily Nepetoideae. One of several genera referred to as sage, it includes the produced herb used in cooking, Salvia officinalis; the genus is distributed throughout the Old World and the Americas, with three distinct regions of diversity: Central and South America. The name Salvia derives from the Latin salvere, the verb related to salus, referring to the herb's healing properties. Pliny the Elder was the first author known to describe a plant called "Salvia" by the Romans describing the type species for the genus Salvia, Salvia officinalis; the common modern English name sage derives from Middle English sawge, borrowed from Old French sauge, like the botanical name, stems from Latin salvere. When used without modifiers, the name'sage' refers to Salvia officinalis; the ornamental species are referred to by their genus name Salvia.
Salvia species include biennial, or perennial herbs, along with woody subshrubs. The stems are angled like other members in Lamiaceae; the leaves are entire, but sometimes toothed or pinnately divided. The flowering stems bear small bracts, dissimilar to the basal leaves—in some species the bracts are ornamental and showy; the flowers are produced in racemes, or panicles, produce a showy display with flower colors ranging from blue to red, with white and yellow less common. The calyx is tubular or bell shaped, without bearded throats, divided into two parts or lips, the upper lip entire or three-toothed, the lower two-cleft; the corollas are claw shaped and are two-lipped. The upper lip is entire or three-toothed; the lower lip has two lobes. The stamens are reduced to two short structures with anthers two-celled, the upper cell fertile, the lower imperfect; the flower styles are two-cleft. The fruits are smooth ovoid or oblong nutlets and in many species they have a mucilaginous coating. Many members of Salvia have trichomes growing on the leaves and flowers, which help to reduce water loss in some species.
Sometimes the hairs are glandular and secrete volatile oils that give a distinct aroma to the plant. When the hairs are rubbed or brushed, some of the oil-bearing cells are ruptured; this results in the plant being unattractive to grazing animals and some insects. The defining characteristic of the genus Salvia is the unusual pollination mechanism, it is central to any investigation into the systematics, species radiation, or pollination biology of Salvia. It consists of two stamens and the two thecae on each stamen are separated by an elongate connective, it is the elongation of the connective. Sprengel was the first to describe the nototribic pollination mechanism in Salvia; when a pollinator probes a male stage flower for nectar, the lever causes the stamens to move and the pollen to be deposited on the pollinator. When the pollinator withdraws from the flower, the lever returns the stamens to their original position. In older, female stage flowers, the stigma is bent down in a general location that corresponds to where the pollen was deposited on the pollinator's body.
The lever of most Salvia species is not specialized for a single pollinator, but is generic and selected to be released by many bird and bee pollinators of varying shapes and sizes. The lever arm can be specialized to be different lengths so that the pollen is deposited on different parts of the pollinator’s body. For example, if a bee went to one flower and pollen was deposited on the far back of her body, but it flew to another flower where the stigma was more forward, pollination could not take place; this can result in reproductive isolation from the parental population and new speciation can occur. It is believed that the lever mechanism is a key factor in the speciation, adaptive radiation, diversity of this large genus. George Bentham was first to give a full monographic account of the genus in 1832–1836, based his classifications on staminal morphology. Bentham's work on classifying the family Labiatae is still the only comprehensive and global organization of the family. While he was clear about the integrity of the overall family, he was less confident about his organization of Salvia, the largest genus in Labiatae.
Based on his own philosophy of classification, he wrote that he "ought to have formed five or six genera" out of Salvia. In the end, he felt that the advantage in placing a uniform grouping in one genus was "more than counterbalanced by the necessity of changing more than two hundred names." At that time there were only 291 known Salvia species. Bentham organized Salvia into twelve sections, based on differences in corolla and stamens; these were placed into four subgenera that were divided into Old World and New World species: Subgenus Salvia: Old World Subgenus Sclarea: Old World Subgenus Calosphace: N
In the APG IV system for the classification of flowering plants, the name asterids denotes a clade. Common examples include the forget-me-nots, the common sunflower, morning glory and sweet potato, lavender, olive, honeysuckle, ash tree, snapdragon, psyllium, garden sage, table herbs such as mint and rosemary, rainforest trees such as Brazil nut. Most of the taxa belonging to this clade had been referred to the Asteridae in the Cronquist system and to the Sympetalae in earlier systems; the name asterids resembles the earlier botanical name but is intended to be the name of a clade rather than a formal ranked name, in the sense of the ICBN. The phylogenetic tree presented hereafter has been proposed by the APG IV project. Genetic analysis carried out after APG II maintains that the sister to all other asterids are the Cornales. A second order that split from the base of the asterids are the Ericales; the remaining orders cluster into two clades, the lamiids and the campanulids. The structure of both of these clades has changed in APG III.
In APG III system, the following clades were renamed: euasterids I → lamiids euasterids II → campanulids Asterids in Stevens, P. F.. Angiosperm Phylogeny Website. Version 7, May 2006
The Lamiaceae or Labiatae are a family of flowering plants known as the mint or deadnettle family. Many of the plants are aromatic in all parts and include used culinary herbs, such as basil, rosemary, savory, oregano, thyme and perilla; some species are shrubs, trees, or vines. Many members of the family are cultivated, not only for their aromatic qualities, but their ease of cultivation, since they are propagated by stem cuttings. Besides those grown for their edible leaves, some are grown for decorative foliage, such as Coleus. Others are grown for seed, such as Salvia hispanica, or for their edible tubers, such as Plectranthus edulis, Plectranthus esculentus, Plectranthus rotundifolius, Stachys affinis; the family has a cosmopolitan distribution. The enlarged Lamiaceae contain about 236 genera and have been stated to contain 6,900 to 7,200 species, but the World Checklist lists 7,534; the largest genera are Salvia, Stachys, Hyptis, Vitex and Nepeta. Clerodendrum was once a genus of over 400 species, but by 2010, it had been narrowed to about 150.
The family has traditionally been considered related to the Verbenaceae. The alternate family name Labiatae refers to the fact that the flowers have petals fused into an upper lip and a lower lip; the flowers are bilaterally symmetrical with five united sepals. They are bisexual and verticillastrate. Although this is still considered an acceptable alternative name, most botanists now use the name Lamiaceae in referring to this family; the leaves each pair at right angles to the previous one or whorled. The stems are square in cross section, but this is not found in all members of the family, is sometimes found in other plant families; the last revision of the entire family was published in 2004. It provided keys to 236 genera; these are marked with an asterisk in the list below. A few genera have been established or resurrected since 2004; these are marked with a plus sign. The remaining genera in the list are of historical interest only and are from a source that includes such genera without explanation.
Few of these are recognized in modern treatments of the family. Kew Gardens provides a list of genera. A list at the Angiosperm Phylogeny Website is updated; the circumscription of several genera has changed since 2004. Tsoongia and Viticipremna have been sunk into synonymy with Vitex. Huxleya has been sunk into Volkameria. Kalaharia, Volkameria and Tetraclea have been segregated from a polyphyletic Clerodendrum. Rydingia has been separated from Leucas; the remaining Leucas is paraphyletic over four other genera. In 2004, the Lamiaceae were divided into seven subfamilies with 10 genera not placed in any of the subfamilies; the unplaced genera are: Tectona, Hymenopyramis, Peronema, Cymaria, Acrymia and Ombrocharis. The subfamilies are the Symphorematoideae, Ajugoideae, Prostantheroideae, Nepetoideae and Lamioideae; the subfamily Viticoideae is not monophyletic. The Prostantheroideae and Nepetoideae are divided into tribes; these are shown in the phylogenetic tree below. Most of the genera of Lamiaceae have never been sampled for DNA for molecular phylogenetic studies.
Most of those that have been are included in the following phylogenetic tree. The phylogeny depicted below is based on seven different sources. Lamiaceae in L. Watson and M. J. Dallwitz; the families of flowering plants: descriptions, identification, information retrieval. Http://delta-intkey.com