Avicenna was a Persian polymath, regarded as one of the most significant physicians, astronomers and writers of the Islamic Golden Age. He has been described as the father of early modern medicine. Of the 450 works he is known to have written, around 240 have survived, including 150 on philosophy and 40 on medicine, his most famous works are The Book of Healing, a philosophical and scientific encyclopedia, The Canon of Medicine, a medical encyclopedia which became a standard medical text at many medieval universities and remained in use as late as 1650. In 1973, Avicenna's Canon Of Medicine was reprinted in New York. Besides philosophy and medicine, Avicenna's corpus includes writings on astronomy, alchemy and geology, Islamic theology, mathematics and works of poetry. Avicenna is a Latin corruption of the Arabic patronym ibn Sīnā, meaning "Son of Sina". However, Avicenna was not the son but the great-great-grandson of a man named Sina, his formal Arabic name was Abū ʿAlī al-Ḥusayn ibn ʿAbdillāh ibn al-Ḥasan ibn ʿAlī ibn Sīnā.
Ibn Sina created an extensive corpus of works during what is known as the Islamic Golden Age, in which the translations of Greco-Roman and Indian texts were studied extensively. Greco-Roman texts translated by the Kindi school were commented and developed by Islamic intellectuals, who built upon Persian and Indian mathematical systems, algebra and medicine; the Samanid dynasty in the eastern part of Persia, Greater Khorasan and Central Asia as well as the Buyid dynasty in the western part of Persia and Iraq provided a thriving atmosphere for scholarly and cultural development. Under the Samanids, Bukhara rivaled Baghdad as a cultural capital of the Islamic world; the study of the Quran and the Hadith thrived in such a scholarly atmosphere. Philosophy and theology were further developed, most noticeably by Avicenna and his opponents. Al-Razi and Al-Farabi had provided knowledge in medicine and philosophy. Avicenna had access to the great libraries of Balkh, Gorgan, Rey and Hamadan. Various texts show.
Aruzi Samarqandi describes how before Avicenna left Khwarezm he had met Al-Biruni, Abu Nasr Iraqi, Abu Sahl Masihi and Abu al-Khayr Khammar. Avicenna was born c. 980 in Afshana, a village near Bukhara, the capital of the Samanids, a Persian dynasty in Central Asia and Greater Khorasan. His mother, named Sitāra, was from Bukhara, his father worked in the government of Samanid in a Sunni regional power. After five years, his younger brother, was born. Avicenna first began to learn the Quran and literature in such a way that when he was ten years old he had learned all of them. According to his autobiography, Avicenna had memorised the entire Quran by the age of 10, he learned Indian arithmetic from an Indian greengrocer, Mahmoud Massahi and he began to learn more from a wandering scholar who gained a livelihood by curing the sick and teaching the young. He studied Fiqh under the Sunni Hanafi scholar Ismail al-Zahid. Avicenna was taught some extent of philosophy books such as Introduction's Porphyry, Euclid's Elements, Ptolemy's Almagest by an unpopular philosopher, Abu Abdullah Nateli, who claimed philosophizing.
As a teenager, he was troubled by the Metaphysics of Aristotle, which he could not understand until he read al-Farabi's commentary on the work. For the next year and a half, he studied philosophy. In such moments of baffled inquiry, he would leave his books, perform the requisite ablutions go to the mosque, continue in prayer till light broke on his difficulties. Deep into the night, he would continue his studies, in his dreams problems would pursue him and work out their solution. Forty times, it is said, he read through the Metaphysics of Aristotle, till the words were imprinted on his memory. So great was his joy at the discovery, made with the help of a work from which he had expected only mystery, that he hastened to return thanks to God, bestowed alms upon the poor, he turned to medicine at 16, not only learned medical theory, but by gratuitous attendance of the sick had, according to his own account, discovered new methods of treatment. The teenager achieved full status as a qualified physician at age 18, found that "Medicine is no hard and thorny science, like mathematics and metaphysics, so I soon made great progress.
The youthful physician's fame spread and he treated many patients without asking for payment. A number of theories have been proposed regarding Avicenna's madhab. Medieval historian Ẓahīr al-dīn al-Bayhaqī considered Avicenna to be a follower of the Brethren of Purity. On the other hand, Dimitri Gutas along with Aisha Khan and Jules J. Janssens demonstrated that Avicenna was a Sunni
An estuary is a enclosed coastal body of brackish water with one or more rivers or streams flowing into it, with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments, they are subject both to marine influences—such as tides and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are classified according to their geomorphological features or to water-circulation patterns, they can have many different names, such as bays, lagoons, inlets, or sounds, although some of these water bodies do not meet the above definition of an estuary and may be saline.
The banks of many estuaries are amongst the most populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation and other poor farming practices; the word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary; the most accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, within which sea water is measurably diluted with freshwater derived from land drainage". However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff.
This broad definition includes fjords, river mouths, tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides; the sea water entering the estuary streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, the extent of evaporation of the water in the estuary. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley; this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border; the width-to-depth ratio of these estuaries is large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths exceed 30 m.
Examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, Delaware Bay along the Mid-Atlantic coast, Galveston Bay and Tampa Bay along the Gulf Coast. Bar-built estuaries are found in place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands, they are common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches encloses the estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries develop on sloping plains located along tectonically stable edges of continents and marginal sea coasts, they are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m. The barrier beaches that enclose bar-built estuaries have been developed in several ways: building up of offshore bars by wave action, in which sand from the sea floor is deposited in elongated bars parallel to the shoreline, reworking of sediment discharge from rivers by wave and wind action into beaches, overwash flats, dunes, engulfment of mainland beach ridges due to sea level rise and resulting in the breaching of the ridges and flooding of the coastal lowlands, forming shallow lagoons, elongation of barrier spits from the erosion of headlands due to the action of longshore currents, with the spits growing in the direction of the littoral drift.
Barrier beaches form in shallow water and are parallel to the shoreline, resulting in long, narrow estuaries. The average water depth is less than 5 m, exceeds 10 m. Examples of bar-built estuaries are Barnegat Bay, New Jersey. Fjords were formed where pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross s
Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
All Species Foundation Catalogue of Life Encyclopedia of Life Tree of Life Web Project List of online encyclopedias The Plant List Wikispecies, The free species directory that anyone can edit Species Community Portal The Wikispecies Charter, written by Wales
In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. Trees tend to be long-lived, some reaching several thousand years old. In wider definitions, the taller palms, tree ferns and bamboos are trees. Trees have been in existence for 370 million years, it is estimated. A tree has many secondary branches supported clear of the ground by the trunk; this trunk contains woody tissue for strength, vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark. Below the ground, the roots spread out widely. Above ground, the branches divide into smaller shoots.
The shoots bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Trees reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms and bamboos produce seeds, but tree ferns produce spores instead. Trees play a significant role in moderating the climate, they remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture; because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, they play a role in many of the world's mythologies.
Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are typically defined by height, with smaller plants from 0.5 to 10 m being called shrubs, so the minimum height of a tree is only loosely defined. Large herbaceous plants such as papaya and bananas are trees in this broad sense. A applied narrower definition is that a tree has a woody trunk formed by secondary growth, meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the growing tip. Under such a definition, herbaceous plants such as palms and papayas are not considered trees regardless of their height, growth form or stem girth. Certain monocots may be considered trees under a looser definition.
Aside from structural definitions, trees are defined by use. The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight. Trees tend some reaching several thousand years old. Several trees are among the oldest organisms now living. Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage, they differ from shrubs, which have a similar growth form, by growing larger and having a single main stem. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species; the greatest number of these grow in tropical regions and many of these areas have not yet been surveyed by botanists, making tree diversity and ranges poorly known.
The majority of tree species are angiosperms. There are about 1000 species of gymnosperm trees, including conifers, cycads and gnetales. Most angiosperm trees are eudicots, the "true dicotyledons", so named because the seeds contain two cotyledons or seed leaves. There are some trees among the old lineages of flowering plants called basal angiosperms or paleodicots. Wood gives structural strength to the trunk of most types of tree; the vascular system of trees allows water and other chemicals to be di
Aerial roots are roots above the ground. They are always adventitious, they are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rata and pohutukawa trees of New Zealand and vines such as Common Ivy and poison ivy. This plant organ, found in so many diverse plant families has different specializations that suit the plant habitat. In general growth form, they can be technically classed as negatively gravitropic or positively gravitropic. Banyan trees are an example of a strangler figs that begin life as an epiphyte in the crown of another tree, their roots grow down and around the stem of the host, their growth accelerating once the ground has been reached. Over time, the roots coalesce to form a pseudotrunk, which may give the appearance that it is strangling the host. Another strangler that begins life as an epiphyte is the Moreton Bay Fig of tropical and subtropical eastern Australia, which has powerfully descending aerial roots.
In the subtropical to warm-temperate rainforests of northern New Zealand, Metrosideros robusta, the rata tree, sends aerial roots down several sides of the trunk of the host. From these descending roots, horizontal roots grow out to girdle the trunk and fuse with the descending roots. In some cases the "strangler" outlives the host tree, leaving as its only trace a hollow core in the massive pseudotrunk of the rata; these specialized aerial roots enable plants to breathe air in habitats. The roots may grow down from the stem, or up from typical roots; some botanists classify these as aerating roots rather than aerial roots. The surface of these roots are covered with lenticel which take up air into spongy tissue which in turn uses osmotic pathways to spread oxygen throughout the plant as needed. Pneumatophores differentiate the Black mangrove and Grey mangrove from other mangrove species. Fishermen in some areas of Southeast Asia make corks for fishing nets by shaping the pneumatophores of Sonneratia caseolaris into small floats.
Members of the subfamily Taxodioideae produce woody aboveground structures, known as cypress knees, that project upward from their roots. These structures were thought to function as pneumatophores, but recent experiments have failed to find evidence for this hypothesis; when the soil upon which a halophytic plant is growing is salinic and anaerobic soil, in order to aide in respiration, the plant shoots pneumatophores. It is important to mention that in other plants the gaseous exchange, done at leaves is of minimal work for roots which are a lot further away. Roots absorb their own, oxygen from the soil. However, since saline soil is anaerobic it becomes impossible for the roots to do gaseous exchange through soil and hence form pneumatophores that can absorb oxygen directly from air; these roots are found in parasitic plants, where aerial roots become cemented to the host plant via a sticky attachment disc before intruding into the tissues of the host. Mistletoe is a good example of this. Adventitious roots develop from plantlet nodes formed via horizontal, aboveground stems, termed stolons, e.g. strawberry runners and spider plant.
Some leaves develop adventitious buds, which form adventitious roots, e.g. piggyback plant and mother-of-thousands. The adventitious plantlets drop off the parent plant and develop as separate clones of the parent. Aerial roots may receive nutrient intake from the air. There are many types of aerial roots, some such as mangrove aerial roots, are used for aeration and not for water absorption. In other cases they are used for structure, in order to reach the surface. Many plants rely on the leaf system onto scales; these roots function. Most aerial roots directly absorb the moisture from humid air; some surprising results in studies on aerial roots of orchids show that the'Velamen' - the white spongy envelop of the aerial roots, are totally water proof, preventing water loss but not allowing any water in. Once reaching and touching a surface the Velamen is not produced in the contact area, allowing the root to absorb water like terrestrial roots. Many other epiphytes - non-parasitic or semi-parasitic plants living on the surface of other plants, have developed cups and scales that gather rainwater or dew.
The aerial roots in this case work as regular surface roots. There are several types of roots creating a cushion where a high humidity is retained; some of the aerial roots in the genus Tillandsia, have a physiology that collects water from humidity, absorbs it directly. Adventitious Root Vegetative reproduction Vine Aeroponics
Acanthaceae is a family of dicotyledonous flowering plants containing 250 genera and about 2500 species. Most are shrubs, or twining vines. Only a few species are distributed in temperate regions; the four main centres of distribution are Indonesia and Malaysia, Africa and Central America. Representatives of the family can be found in nearly every habitat, including dense or open forests, wet fields and valleys, sea coast and marine areas and mangrove forests. Plants in this family have simple, decussated leaves with entire margins, without stipules; the leaves may contain calcium carbonate concretions, seen as streaks on the surface. The flowers are perfect, zygomorphic to nearly actinomorphic, arranged in an inflorescence, either a spike, raceme, or cyme. A colorful bract subtends each flower; the calyx has four or five lobes. The fruit is a two-celled capsule, dehiscing somewhat explosively. In most species, the seeds are attached to a hooked stalk that ejects them from the capsule; this trait is shared by all members of the clade Acanthoideae.
A 1995 study of seed expulsion in Acanthaceae used high speed video pictures to show that retinacula propel seeds away from the parent plant when the fruits dehisce, thereby helping the plant gain maximum seed dispersal range. A species well known to temperate gardeners is bear's breeches, a herbaceous perennial plant with big leaves and flower spikes up to 2 m tall. Tropical genera familiar to gardeners include Justicia. Avicennia, a genus of mangrove trees placed in Verbenaceae or in its own family, Avicenniaceae, is included in Acanthaceae by the Angiosperm Phylogeny Group on the basis of molecular phylogenetic studies that show it to be associated with this family. Traditionally the most important part use in Acanthaceae is the leaves and they are used externally for wounds; some research has indicated that Acanthaceae possess antifungal, anti-inflammatory, anti-pyretic, insecticidal, immunomodulatory, anti-platelet aggregation and anti-viral potential. For instance, Acanthus ilicifolius, whose chemical composition has been researched, is used in ethnopharmaceutical applications, including in Indian and Chinese traditional medicine.
Various parts of Acanthus ilicifolius have been used to treat asthma, leprosy, snake bites, rheumatoid arthritis. The leaves of Acanthus ebracteatus, noted for their antioxidant properties, are used for making Thai herbal tea in Thailand and Indonesia. Phytochemical reports on family Acanthaceae are glycosides, benzonoids, phenolic compounds and triterpenoids. Since the first comprehensive classification of Acanthaceae in 1847 by Nees, there have been a few major revisions presented since for the whole family. Lindau, in 1895, divided the family into the subfamilies Mendoncioideae, Thunbergioideae and Acanthoideae. Critically, Mendoncioideae and Nelsonioideae do not possess retinaculate fruits—and it is this distinction, between classifying Acanthaceae into a family that includes those clades with non-retinaculate fruits and one that excludes them, that still persists to the modern day. Bremekamp, in 1965, presented a classification of Acanthaceae that differed from that of Lindau, for his Acanthaceae excluded genera that lack retinaculate fruits.
He placed Nelsonioideae within Scrophulariaceae, classified Thunbergiaceae and Mendonciaceae as distinct families and divided his Acanthaceae into two groups based on the presence or absence of cystoliths, articulate stems, monothecate anthers, colpate pollen. In Scotland and Vollesen's 2000 study, they accepted 221 genera and detailed five major groups within Acanthaceae s.s., equivalent to Acanthoideae Link sensu Lindau 1895. Out of those 221 genera, they placed 201 of them into seven infrafamilial taxa of Acanthaceae, leaving only 20 unplaced. In the current understanding of Acanthaceae, Acanthaceae s.s. includes only those clades with retinaculate fruits, while Acanthaceae s.l. includes those clades as well as Thunbergioideae and Avicennia. Much research, using both molecular data and fossils, has been conducted in recent years regarding the dating and distribution of the Acanthaceae and Lamiales lineage, although there still remains some ambiguity. In a 2004 study on the molecular phylogenetic dating of asterid flowering plants, researchers estimated 106 million years for the stem lineage of Lamiales, 67 MY for the stem lineage of Acanthaceae, 54 MY for the crown node of Acanthaceae.
These estimates are older than those based on fossils that can confidently be assigned to Lamiales, which are middle Eocene in age, ca. 48-37 MY. Palynomorphs that definitively show the existence of Acanthaceae are known from the upper Miocene, with the oldest ca. 22 MY. The 246 accepted genera, according to Germplasm Resources Information Network, are: Thomandersia Baill. → Thomandersiaceae Schwarzbach, Andrea E.. "Phylogenetic relationships of the mangrove family Avicenniaceae based on chloroplast and nuclear ribosomal DNA seq
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