Buxus colchica is a species of Buxus native to Azerbaijan, Georgia and Turkey. It is threatened by habitat loss, it is an evergreen shrub or small tree closely related to Buxus sempervirens, treated as a synonym of it. It does not differ from B. sempervirens in any visible character
The eudicots, Eudicotidae or eudicotyledons are a clade of flowering plants, called tricolpates or non-magnoliid dicots by previous authors. The botanical terms were introduced in 1991 by evolutionary botanist James A. Doyle and paleobotanist Carol L. Hotton to emphasize the evolutionary divergence of tricolpate dicots from earlier, less specialized, dicots; the close relationships among flowering plants with tricolpate pollen grains was seen in morphological studies of shared derived characters. These plants have a distinct trait in their pollen grains of exhibiting three colpi or grooves paralleling the polar axis. Molecular evidence confirmed the genetic basis for the evolutionary relationships among flowering plants with tricolpate pollen grains and dicotyledonous traits; the term means "true dicotyledons", as it contains the majority of plants that have been considered dicots and have characteristics of the dicots. The term "eudicots" has subsequently been adopted in botany to refer to one of the two largest clades of angiosperms, monocots being the other.
The remaining angiosperms include magnoliids and what are sometimes referred to as basal angiosperms or paleodicots, but these terms have not been or adopted, as they do not refer to a monophyletic group. The other name for the eudicots is tricolpates, a name which refers to the grooved structure of the pollen. Members of the group have tricolpate pollen; these pollens have three or more pores set in furrows called colpi. In contrast, most of the other seed plants produce monosulcate pollen, with a single pore set in a differently oriented groove called the sulcus; the name "tricolpates" is preferred by some botanists to avoid confusion with the dicots, a nonmonophyletic group. Numerous familiar plants are eudicots, including many common food plants and ornamentals; some common and familiar eudicots include members of the sunflower family such as the common dandelion, the forget-me-not and other members of its family, buttercup and macadamia. Most leafy trees of midlatitudes belong to eudicots, with notable exceptions being magnolias and tulip trees which belong to magnoliids, Ginkgo biloba, not an angiosperm.
The name "eudicots" is used in the APG system, of 1998, APG II system, of 2003, for classification of angiosperms. It is applied to a monophyletic group, which includes most of the dicots. "Tricolpate" is a synonym for the "Eudicot" monophyletic group, the "true dicotyledons". The number of pollen grain furrows or pores helps classify the flowering plants, with eudicots having three colpi, other groups having one sulcus. Pollen apertures are any modification of the wall of the pollen grain; these modifications include thinning and pores, they serve as an exit for the pollen contents and allow shrinking and swelling of the grain caused by changes in moisture content. The elongated apertures/ furrows in the pollen grain are called colpi, along with pores, are a chief criterion for identifying the pollen classes; the eudicots can be divided into two groups: the basal eudicots and the core eudicots. Basal eudicot is an informal name for a paraphyletic group; the core eudicots are a monophyletic group.
A 2010 study suggested the core eudicots can be divided into two clades, Gunnerales and a clade called "Pentapetalae", comprising all the remaining core eudicots. The Pentapetalae can be divided into three clades: Dilleniales superrosids consisting of Saxifragales and rosids superasterids consisting of Santalales, Berberidopsidales and asteridsThis division of the eudicots is shown in the following cladogram: The following is a more detailed breakdown according to APG IV, showing within each clade and orders: clade Eudicots order Ranunculales order Proteales order Trochodendrales order Buxales clade Core eudicots order Gunnerales order Dilleniales clade Superrosids order Saxifragales clade Rosids order Vitales clade Fabids order Fabales order Rosales order Fagales order Cucurbitales order Oxalidales order Malpighiales order Celastrales order Zygophyllales clade Malvids order Geraniales order Myrtales order Crossosomatales order Picramniales order Malvales order Brassicales order Huerteales order Sapindales clade Superasterids order Berberidopsidales order Santalales order Caryophyllales clade Asterids order Cornales order Ericales clade Campanulids order Aquifoliales order Asterales order Escalloniales order Bruniales order Apiales order Dipsacales order Paracryphiales clade Lamiids order Solanales order Lamiales order Vahliales order Gentianales order Boraginales order Garryales order Metteniusales order Icacinales Eudicots at the Encyclopedia of Life Eudicots, Tree of Life Web Project Dicots Plant Life Forms
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
A chess piece, or chessman, is any of the six different movable objects used on a chessboard to play the game of chess. Each player begins with a total of sixteen pieces; the pieces that belong to each player are distinguished by color. The lighter colored pieces are referred to as "white," and the player that owns them, "White"; the darker colored pieces are referred to as "black", the player that owns them, "Black". The word "piece" has three meanings, depending on the context; the context should make the intended meaning clear. It may mean any including the pawns; when used this way, "piece" is synonymous with "chessman" or "man". In play, the term is used to exclude pawns, referring only to a queen, bishop, knight, or king. In this context, the pieces can be broken down into three groups: major pieces, minor pieces, the king. In phrases such as "winning a piece", "losing a piece" or "sacrificing a piece", it refers only to a bishop or knight; the queen and pawn are specified by name in these cases, for example, "winning a queen", "losing a rook", or "sacrificing a pawn".
In the first context, each of the two players begins with the following sixteen pieces in a standard game: 1 king 1 queen 2 rooks 2 bishops 2 knights 8 pawns The rules of chess prescribe the types of move a player can make with each type of chess piece. Each piece type moves in a different way. During play, the players take; the rook moves any number of vacant squares forwards, left, or right in a straight line. It takes part, along with the king, in a special move called castling; the bishop moves any number of vacant squares diagonally in a straight line. A bishop stays on squares of the same color throughout a game; the two bishops each player starts with move on squares of opposite colors. The queen moves any number of vacant squares in any direction: forwards, left, right, or diagonally, in a straight line; the king moves one vacant square in any direction: forwards, left, right, or diagonally. It has a special move called castling, in which the king moves two squares towards one of its own rooks and in the same move, the rook jumps over the king to land on the square on the king's other side.
Castling may only be performed if the king and rook involved have never been moved in the game, only if there are no pieces between the rook and the king. The knight moves on an extended diagonal from one corner of any 2×3 rectangle of squares to the furthest opposite corner; the knight alternates its square color each time it moves. Other than the castling move described above where the rook jumps over the king, the knight is the only piece permitted to jump over any intervening piece when moving; the pawn moves forward one space, or optionally, two spaces when on its starting square, toward the opponent's side of the board. When there is an enemy piece one square diagonally ahead of the pawn, either left or right the pawn may capture that piece. A pawn can perform a special type of capture of an enemy pawn called en passant. If the pawn reaches a square on the back rank of the opponent, it promotes to the player's choice of a queen, bishop, or knight. Pieces other than pawns capture in the same way.
A capturing piece replaces the opponent piece on its square, except for an en passant capture. Captured pieces are removed from the game. A square may hold only one piece at any given time. Except for castling and the knight's move, no piece may jump over another piece; the variety of designs available is broad, from small cosmetic changes to abstract representations, to themed designs such as those that emulate the drawings from the works of Lewis Carroll, or modern treatments such as Star Trek or The Simpsons. Themed designs are intended for display purposes rather than actual play; some works of art are designs of chess sets, such as the modernist chess set by chess enthusiast and dadaist Man Ray, on display in the Museum of Modern Art in New York City. Chess pieces used for play are figurines that are taller than they are wide. For example, a set of pieces designed for a chessboard with 2.25 inches squares have a king around 3.75 inches tall. Chess sets are available in a variety of designs, with the most well-known Staunton design, named after Howard Staunton, a 19th-century English chess player, designed by Nathaniel Cooke.
The first Staunton style sets were made in 1849 by Jaques of London. Wooden White chess pieces are made of a light wood, boxwood, or sometimes maple. Black wooden pieces are made of a dark wood such as rosewood, red sandalwood, African Padauk wood or walnut. Sometimes they are made of brown, or red. Plastic white pieces are made of white or off-white plastic, plastic black pieces are made of black or red plastic. Sometimes other materials are used, such as ivory, or a composite material. For actual play, pieces of the Staunton chess set design are standard; the height of the king should be betw
Gothic boxwood miniature
Gothic boxwood miniatures are small religious wood sculptures produced during the 15th and 16th centuries in today's Low Countries, at the end of the Gothic period of the emerging Northern Renaissance. They consist of intricate layers of reliefs rendered to nearly microscopic level; the miniatures are made from boxwood wood carvings. Buxus has a fine grain and high density suitable for detailed micro-carving. There are around 150 surviving examples; the majority are spherical beads, skulls, or coffins. The polyptychs are 10–13 cm in height. Most of the beads are 10–15 cm in diameter, designed so they could be held in the palm of a hand during personal devotion or hung from necklaces or belts as fashionable accessories. Boxwood miniatures were prized in the early 16th century, their iconography and utility can be linked to medieval ivory carvings, as well as contemporary illuminated miniatures, panel paintings, sculpture and engravings. They contain imagery from the life of Mary, the Crucifixion of Jesus, vistas of Heaven and Hell.
Each miniature's production required exceptional craftsmanship, some may have taken decades of cumulative work to complete, suggesting that they were commissioned by high-ranking nobles. A number of the miniatures appear to have come from a workshop led by Adam Dircksz, thought to have produced dozens of miniatures. Nothing is known about Dircksz or the artisans who produced the miniatures; some of the original owners can be identified from markings initials or coats of arms, emplaced by the sculptors. Important collections of boxwood miniatures are in the Art Gallery of Ontario, in the British Museum as part of the Waddesdon Bequest, at the Metropolitan Museum of Art, New York; because of their rarity and the difficulty in discerning their intricacy from reproductions, boxwood miniatures have not been as studied as other forms of Netherlandish visual art. Boxwood is a dense hardwood with fine grain, resistant to splitting and chipping—ideal for wood carving. In the 16th century, woodcut blocks used for woodblock printing were made of boxwood.
Uses for boxwood were similar to those for ivory in medieval carvings, but with boxwood a far less expensive option than ivory. Designs were overseen by master craftsmen who must have had access to prints and woodcuts of contemporary works of art, who were influenced by diptych and triptych panel paintings. Boxwood grows so the trunk remains narrow, a fact that impedes the size of any carvings made from any single piece; the wood assumes an soft and tactile surface if polished or handled, such as was the case for prayer nuts. The wood loses its tactility. Polychromy reduced the legibility of the carvings, "quite apart from the difficulty of coloring such tiny and complex scenes" as the art historian Frits Scholten has noted; the tools used in production were similar to those used in the production of larger altarpieces and included saws, card scrapers, augers and gimlets. Wood was cut into the required dimensions as blocks. Prayer beads were made on a lathe used to turn the wood; the woodcutters carved a single block of boxwood into a sphere, cut it in half, hollowed it out, attached a fastening hinge and carrying loops.
The carvings in the interiors were made separately from the smaller hemispheres and fitted onto an outer shell. In some cases, these wooden shells were placed in a silver housing; because of their diminutive scale, the pieces were produced using magnifying glasses. The small wood pieces were difficult to brace during carving, they were positioned on a bench, between two posts, so that they could be turned around. Domed spaces, intended to evoke church architecture, were drilled or carved, these were divided using compasses and a straightedge into pie-shaped segments. A surface plane was established onto; these were created from multiple separate wood sheets, individually produced before being joined in layers. Major figures saints, were carved from single blocks of wood. Relief components were either glued into prefixed niches, or they were bound with pegs, which were sometimes functional and visible or implanted into the relief form; because of this layered structure, they are fragile. An example of this layering technique is in the Last Judgement prayer bead attributed to Adam Dircksz and now located at the Art Gallery of Ontario, where some thirty minuscule, individually carved spikes are set into the ceiling vault and around Christ to suggest rays of light.
Punctuations in the wood suggesting stars were added to the ceiling via tiny drilled holes. The level of detail indicates the use of magnification in their production with the same instruments used by contemporary jewellers. Describing these intricacies, the art historian Eve Kahn writes that the works can be so rich that "individual feathers are visible on angel wings, dragon skins are textured with thick scales. Crumbling shacks are shown with shingles missing from their gabled roofs. Saints' robes and soldiers' uniforms are trimmed with buttons and embroidery, there are minute representations of jewelry and rosary beads". Only one miniature is explicitly dated, a triptych in the Waddesdon Bequest at the British Museum is inscribed with "1511". A minority bear other indications of origin or the source of commission. A
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