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
Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 12th–9th centuries BC to the end of antiquity. Following this period was the beginning of the Early Middle Ages and the Byzantine era. Three centuries after the Late Bronze Age collapse of Mycenaean Greece, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and colonization of the Mediterranean Basin; this was followed by the period of Classical Greece, an era that began with the Greco-Persian Wars, lasting from the 5th to 4th centuries BC. Due to the conquests by Alexander the Great of Macedon, Hellenistic civilization flourished from Central Asia to the western end of the Mediterranean Sea; the Hellenistic period came to an end with the conquests and annexations of the eastern Mediterranean world by the Roman Republic, which established the Roman province of Macedonia in Roman Greece, the province of Achaea during the Roman Empire. Classical Greek culture philosophy, had a powerful influence on ancient Rome, which carried a version of it to many parts of the Mediterranean Basin and Europe.
For this reason, Classical Greece is considered to be the seminal culture which provided the foundation of modern Western culture and is considered the cradle of Western civilization. Classical Greek culture gave great importance to knowledge. Science and religion were not separate and getting closer to the truth meant getting closer to the gods. In this context, they understood the importance of mathematics as an instrument for obtaining more reliable knowledge. Greek culture, in a few centuries and with a limited population, managed to explore and make progress in many fields of science, mathematics and knowledge in general. Classical antiquity in the Mediterranean region is considered to have begun in the 8th century BC and ended in the 6th century AD. Classical antiquity in Greece was preceded by the Greek Dark Ages, archaeologically characterised by the protogeometric and geometric styles of designs on pottery. Following the Dark Ages was the Archaic Period, beginning around the 8th century BC.
The Archaic Period saw early developments in Greek culture and society which formed the basis for the Classical Period. After the Archaic Period, the Classical Period in Greece is conventionally considered to have lasted from the Persian invasion of Greece in 480 until the death of Alexander the Great in 323; the period is characterized by a style, considered by observers to be exemplary, i.e. "classical", as shown in the Parthenon, for instance. Politically, the Classical Period was dominated by Athens and the Delian League during the 5th century, but displaced by Spartan hegemony during the early 4th century BC, before power shifted to Thebes and the Boeotian League and to the League of Corinth led by Macedon; this period saw the Greco-Persian Wars and the Rise of Macedon. Following the Classical period was the Hellenistic period, during which Greek culture and power expanded into the Near and Middle East; this period ends with the Roman conquest. Roman Greece is considered to be the period between Roman victory over the Corinthians at the Battle of Corinth in 146 BC and the establishment of Byzantium by Constantine as the capital of the Roman Empire in AD 330.
Late Antiquity refers to the period of Christianization during the 4th to early 6th centuries AD, sometimes taken to be complete with the closure of the Academy of Athens by Justinian I in 529. The historical period of ancient Greece is unique in world history as the first period attested directly in proper historiography, while earlier ancient history or proto-history is known by much more circumstantial evidence, such as annals or king lists, pragmatic epigraphy. Herodotus is known as the "father of history": his Histories are eponymous of the entire field. Written between the 450s and 420s BC, Herodotus' work reaches about a century into the past, discussing 6th century historical figures such as Darius I of Persia, Cambyses II and Psamtik III, alluding to some 8th century ones such as Candaules. Herodotus was succeeded by authors such as Thucydides, Demosthenes and Aristotle. Most of these authors were either Athenian or pro-Athenian, why far more is known about the history and politics of Athens than those of many other cities.
Their scope is further limited by a focus on political and diplomatic history, ignoring economic and social history. In the 8th century BC, Greece began to emerge from the Dark Ages which followed the fall of the Mycenaean civilization. Literacy had been lost and Mycenaean script forgotten, but the Greeks adopted the Phoenician alphabet, modifying it to create the Greek alphabet. Objects with Phoenician writing on them may have been available in Greece from the 9th century BC, but the earliest evidence of Greek writing comes from graffiti on Greek pottery from the mid-8th century. Greece was divided into many small self-governing communities, a pattern dictated by Greek geography: every island and plain is cut off from its neighbors by the sea or mountain ranges; the Lelantine War is the earliest documented war of the ancient Greek period. It was fought between the important poleis of Chalcis and Eretria over the fertile Lelantine plain of Euboea. Both cities seem to have suffered a decline as result of the long war, though Chalcis was the nominal victor.
A mercantile class arose in the first half of the 7th century BC, shown by the introduction of coinage in about 680 BC. This
In agriculture, a plowshare or ploughshare is a component of a plow. It is the cutting or leading edge of a moldboard which follows the coulter when plowing; the plowshare itself is a hardened blade dressed into an integral moldboard so making a unified combination of plowshare and moldboard, the whole being responsible for entering the cleft in the earth and turning the earth over. In well-tilled terrain the plowshare may do duty without a preceding coulter. In modern plows both coulter and plowshare are detachable for easy replacement when worn or broken. Triangular-shaped stone ploughshares are found at the sites of Chinese Majiabang culture dated to 3500 BC around Lake Tai. Ploughshares have been discovered at the nearby Liangzhu and Maqiao sites dated to the same period; the British archaeologist David R. Harris says this indicates that more intensive cultivation in fixed bunded, fields had developed by this time. According to Mu Yongkang and Song Zhaolin's classification and methods of use, the triangular plough assumed many kinds and were the departure from the Hemudu and Luojiajiao spade, with the Songze small plough in mid-process.
The post-Liangzhu ploughs used draft animals. Plowshares are used in heraldry; the ancient phrase from the biblical Book of Isaiah, "to turn swords to ploughshares," is still in common use today. These ploughshares represent peaceful use of wartime capabilities. However, in classical antiquity during the Battle of Marathon, many Persians were slain by a deadly ploughshare-wielding ally who appeared on the side of the ancient Athenians. After their victory and his disappearance, an oracle told the Athenians to worship the hero under the name Echetlaeus: the hero with the echetlon, or ploughshare; the Rotherham Plough - the first commercially successful iron plough
Hesiod was a Greek poet thought by scholars to have been active between 750 and 650 BC, around the same time as Homer. He is regarded as the first written poet in the Western tradition to regard himself as an individual persona with an active role to play in his subject. Ancient authors credited Homer with establishing Greek religious customs. Modern scholars refer to him as a major source on Greek mythology, farming techniques, early economic thought, archaic Greek astronomy and ancient time-keeping; the dating of Hesiod's life is a contested issue in scholarly circles. Epic narrative allowed poets like Homer no opportunity for personal revelations. However, Hesiod's extant work comprises several didactic poems in which he went out of his way to let his audience in on a few details of his life. There are three explicit references in Works and Days, as well as some passages in his Theogony that support inferences made by scholars; the former poem says that his father came from Cyme in Aeolis and crossed the sea to settle at a hamlet, near Thespiae in Boeotia, named Ascra, "a cursed place, cruel in winter, hard in summer, never pleasant".
Hesiod's patrimony there, a small piece of ground at the foot of Mount Helicon, occasioned lawsuits with his brother Perses, who seems, at first, to have cheated him of his rightful share thanks to corrupt authorities or "kings" but became impoverished and ended up scrounging from the thrifty poet. Unlike his father, Hesiod was averse to sea travel, but he once crossed the narrow strait between the Greek mainland and Euboea to participate in funeral celebrations for one Athamas of Chalcis, there won a tripod in a singing competition, he describes a meeting between himself and the Muses on Mount Helicon, where he had been pasturing sheep when the goddesses presented him with a laurel staff, a symbol of poetic authority. Fanciful though the story might seem, the account has led ancient and modern scholars to infer that he was not a professionally trained rhapsode, or he would have been presented with a lyre instead; some scholars have seen Perses as a literary creation, a foil for the moralizing that Hesiod develops in Works and Days, but there are arguments against that theory.
For example, it is quite common for works of moral instruction to have an imaginative setting, as a means of getting the audience's attention, but it could be difficult to see how Hesiod could have travelled around the countryside entertaining people with a narrative about himself if the account was known to be fictitious. Gregory Nagy, on the other hand, sees both Pérsēs and Hēsíodos as fictitious names for poetical personae, it might seem unusual that Hesiod's father migrated from Asia Minor westwards to mainland Greece, the opposite direction to most colonial movements at the time, Hesiod himself gives no explanation for it. However around 750 BC or a little there was a migration of seagoing merchants from his original home in Cyme in Asia Minor to Cumae in Campania, his move west had something to do with that, since Euboea is not far from Boeotia, where he established himself and his family; the family association with Aeolian Cyme might explain his familiarity with eastern myths, evident in his poems, though the Greek world might have developed its own versions of them.
In spite of Hesiod's complaints about poverty, life on his father's farm could not have been too uncomfortable if Works and Days is anything to judge by, since he describes the routines of prosperous yeomanry rather than peasants. His farmer employs a friend as well as servants, an energetic and responsible ploughman of mature years, a slave boy to cover the seed, a female servant to keep house and working teams of oxen and mules. One modern scholar surmises that Hesiod may have learned about world geography the catalogue of rivers in Theogony, listening to his father's accounts of his own sea voyages as a merchant; the father spoke in the Aeolian dialect of Cyme but Hesiod grew up speaking the local Boeotian, belonging to the same dialect group. However, while his poetry features some Aeolisms there are no words that are Boeotian, his basic language was the main literary dialect of Homer's Ionian. It is probable that Hesiod wrote his poems down, or dictated them, rather than passed them on orally, as rhapsodes did—otherwise the pronounced personality that now emerges from the poems would have been diluted through oral transmission from one rhapsode to another.
Pausanias asserted that Boeotians showed him an old tablet made of lead on which the Works were engraved. If he did write or dictate, it was as an aid to memory or because he lacked confidence in his ability to produce poems extempore, as trained rhapsodes could do, it wasn't in a quest for immortal fame since poets in his era had no such notions for themselves. However, some scholars suspect the presence of large-scale changes in the text and attribute this to oral transmission, he composed his verses during idle times on the farm, in the spring before the May harvest or the dead of winter. The personality behind the poems is unsuited to the kind of "aristocratic withdrawal" typical of a rhapsode but is instead "argumentative, suspicious humorous, fond of proverbs, wary of women." He was in fact a misogynist of t
The ard, ard plough, or scratch plough is a simple light plough without a mouldboard. It is symmetrical on either side of its line of draft and is fitted with a symmetrical share that traces a shallow furrow but does not invert the soil, it began to be replaced in most of Europe by the carruca turnplough from the 7th century. In its simplest form it resembles a hoe, consisting of a draft-pole pierced with a nearly vertical, spiked head, dragged through the soil by draft animals and rarely by people; the ard-head is at one end a stilt for steering and at the other a share which gouges the surface ground. More sophisticated models have a composite pole, where the section attached to the head is called the draft-beam, the share may be made of stone or iron; some have two separate stilts for handles. The share comes in two basic forms: a socket share slipped over the nose of the ard-head. Additionally, a slender protruding chisel can be fitted over the top of the mainshare. Rather than cutting and turning the soil to produce ridged furrows, the ard breaks up a narrow strip of soil and cuts a shallow furrow, leaving intervening strips undisturbed.
The ard is not suited for clearing new land, so grass and undergrowth are removed with hoes or mattocks. Cross-ploughing is necessary to break the soil up better, where the soil is tilled twice at right angles to the original direction; this results in square or diamond-shaped fields and is effective at clearing annual weeds. The ard's shallow furrows are ideal for most cereals, if the seed is sown broadcast, the ard can be used to cover the seed in rows. In fact, the ard may have been invented in the Near East to cover seed rather than till; that would explain. The ard is most useful on light soils such as loams or sands, or in mountain fields where the soil is thin, can be safely used in areas where deep ploughing would turn up hardpan or would cause salination or erosion. Ards may be drawn by oxen, water buffalo, camels, or other animals. Ards come in a number of varieties. Based on use, there are two kinds: the tilth ard, for cutting furrows in cleared land, the rip ard, or sod buster, which has a hooked share that gouges deeper into the soil and more clears virgin or fallow land.
The two were in early times used in conjunction with each other. Third is the seed drill ard, used in Mesopotamia, which added a funnel for dropping seed in the furrows as the ard cut them; the earliest and most basic tilth ards are the two-piece models: bow ard, made of a bow-shaped draft-pole pierced by a spear-like head developing a composite body with a separate head and stilt inserted in the pole. The bow ard is the weaker and earlier of the two, it is used for shallow tillage with a tang share, in dry, stony soils. It is restricted to the Mediterranean, Ethiopia and eastern India and Sumatra; the more widespread body ard and heavier for deeper tillage has a socket share, sometimes laterally extended or has serrated wings for better mixing of soil and cutting of weeds. It had a short portion of the body, first made to slide on the furrow bottom and developed into a horizontal body; the body ard dominates in Portugal, western Spain, the Balkans, Sri Lanka, Thailand and most of Latin America.
The bow ard favored the development of a long horizontal sole body sliding on the ground. This led to the sole ard, first attested in Bronze Age Cyprus, being single-handled and consisting of a flat sole into which were set the draft-pole and stilt, meaning there were three separate pieces, their use in Ancient Greek agriculture was described by Hesiod. In northern Europe the single-handled crook ard was favored, consisting of a stilt inserted into a pole with a crook-shaft, i.e. the pole had a curved shape and had a natural crook tip that served as a share. Variations of the sole ard come in two types: the triangular and quadrangular ards; the triangular ard has a horizontal sole body holding the beam and stilt which cross each other, forming a triangle at the base. The quandrangular ard has a horizontal sole body connected to a straight, nearly parallel beam by a stilt and a brace. Evidence of its use in prehistory is sometimes found at archaeological sites where the long, shallow scratches it makes can be seen cutting into the subsoil.
The ard first appears in the mid-Neolithic and is related to the domestication of cattle. It spread with animal traction in general across the cereal-growing cultures of the Neolithic Old World, its exact point of origin is unknown, but it spread throughout West Asia, South Asia and Europe in the late Neolithic and early Chalcolithic. Evidence appears in the Near East in the 6th millennium BC. Iron versions appeared c. 2300 BC both in 3rd-dynasty Egypt. In Europe, the earliest known wooden ard dates from around 2300-2000 BC, but the earliest scratch marks date from 3500-3000 BC. All of these were bow ards depicted in the rock drawings of Bohuslän, Fontanalba, France; the first bow ards were adapted from hoes and like instruments a