1.
Flax
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Flax, Linum usitatissimum, is a member of the genus Linum in the family Linaceae. It is a food and fiber crop cultivated in regions of the world. The textiles made from flax are known in the Western countries as linen, and traditionally used for bed sheets, underclothes, the oil is known as linseed oil. In addition to referring to the plant itself, the word flax may refer to the fibers of the flax plant. The plant species is only as a cultivated plant, and appears to have been domesticated just once from the wild species Linum bienne. Several other species in the genus Linum are similar in appearance to L. usitatissimum, cultivated flax, including some that have similar blue flowers, some of these are perennial plants, unlike L. usitatissimum, which is an annual plant. Cultivated flax plants grow to 1.2 m tall, with slender stems, the leaves are glaucous green, slender lanceolate, 20–40 mm long, and 3 mm broad. The flowers are pale blue, 15–25 mm in diameter. The fruit is a round, dry capsule 5–9 mm in diameter, containing several brown seeds shaped like an apple pip. Flax was first domesticated in the Fertile Crescent region, evidence exists of a domesticated oilseed flax with increased seed size by 9,000 years ago from Tell Ramad in Syria. Use of the crop steadily spread, reaching as far as Switzerland, in China and India, domesticated flax was cultivated also by at least 5,000 years ago. Flax was extensively cultivated in ancient Egypt, where the walls had paintings of flowering flax. Egyptian priests only wore linen, as flax was considered a symbol of purity, phoenicians traded Egyptian linen throughout the Mediterranean, and the Romans used it for their sails. Eventually, Flanders became the center of the linen industry in the European Middle Ages. Since then, flax has lost its importance as a commercial crop, Flax is grown for its oil, used as a nutritional supplement, and as an ingredient in many wood-finishing products. Flax is also grown as a plant in gardens. Flax fibers are used to make linen, the Latin species name usitatissimum means most useful. Flax fibers are taken from the stem of the plant, and are two to three times as strong as those of cotton, additionally, flax fibers are naturally smooth and straight
2.
Pith
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Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store, in eudicots, pith is located in the center of the stem. In monocots, it also into flowering stems and roots. The pith is encircled by a ring of xylem, the xylem, while new pith growth is usually white or pale in color, as the tissue ages it commonly darkens to a deeper brown color. In trees pith is generally present in young growth, but in the trunk, in some plants, the pith in the middle of the stem may dry out and disintegrate, resulting in a hollow stem. A few plants, such as walnuts, have distinctive chambered pith with numerous short cavities, the cells in the peripheral parts of the pith may, in some plants, develop to be different from cells in the rest of the pith. This layer of cells is called the perimedullary region of the pithamus. An example of this can be observed in Hedera helix, a species of ivy, the term pith is also used to refer to the pale, spongy inner layer of the rind - more properly called mesocarp or albedo - of citrus fruits and other hesperidia. The word comes from the Old English word piþa, meaning substance, akin to Middle Dutch pitt, the pith of the sola or other similar plants is used to make the pith helmet. The pith of the palm, although highly toxic to animals in its raw form, is an important human food source in Melanesia and Micronesia by virtue of its starch content. There is an easy, primitive process of extraction from sago pith that leaches away a sufficient amount of the toxins. The form of the starch after processing is similar to tapioca
3.
Xylem
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Xylem is one of the two types of transport tissue in vascular plants, phloem being the other. The basic function of xylem is to water from roots to shoots and leaves. The word xylem is derived from the Greek word ξύλον, meaning wood, the most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape, vessel elements are shorter, Xylem also contains two other cell types, parenchyma and fibers. In transitional stages of plants with secondary growth, the first two categories are not mutually exclusive, although usually a vascular bundle will contain primary xylem only, the branching pattern exhibited by xylem follows Murrays law. Primary xylem is formed during growth from procambium. Metaxylem develops after the protoxylem but before secondary xylem, metaxylem has wider vessels and tracheids than protoxylem. Secondary xylem is formed during growth from vascular cambium. All species have secondary xylem, which is uniform in structure throughout this group. Many conifers become tall trees, the xylem of such trees is used and marketed as softwood. Angiosperms, there are some quarter of a million to four hundred species of angiosperms. Within this group secondary xylem is rare in the monocots, many non-monocot angiosperms become trees, and the secondary xylem of these is used and marketed as hardwood. The xylem transports water and soluble mineral nutrients from the throughout the plant. It is also used to replace water lost during transpiration and photosynthesis, Xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well. The transport is passive, not powered by energy spent by the elements themselves. Transporting sap upwards becomes more difficult as the height of a plant increases, the phloem pressure can rise to several MPa, far higher than atmospheric pressure. Selective inter-connection between these systems allows this high concentration in the phloem to draw xylem fluid upwards by negative pressure. Transpirational pull, Similarly, the evaporation of water from the surfaces of cells to the atmosphere also creates a negative pressure at the top of a plant
4.
Phloem
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In vascular plants, phloem is the living tissue that transports the soluble organic compounds made during photosynthesis, in particular the sugar sucrose, to all parts of the plant where needed. This transport process is called translocation, in trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word φλοιός meaning bark. Sieve elements are the type of cell that are responsible for transporting sugars throughout the plant, at maturity they lack a nucleus and have very few organelles, so they rely on companion cells or albuminous cells for most of their metabolic needs. All sieve cells have groups of pores at their ends that grow from modified and enlarged plasmodesmata, the pores are reinforced by platelets of a polysaccharide called callose. They are of three types, The metabolic functioning of sieve-tube members depends on an association with the companion cells. The dense cytoplasm of a cell is connected to the sieve-tube element by plasmodesmata. The common sidewell shared by a sieve tube element and a cell has large numbers of plasmodesmata. There are two types of companion cells, ordinary companion cells, which have smooth walls and few or no plasmodesmatal connections to cells other than the sieve tube. Transfer cells, which have much-folded walls that are adjacent to non-sieve cells and they are specialized in scavenging solutes from those in the cell walls that are actively pumped requiring energy. Albuminous cells have a role to companion cells, but are associated with sieve cells only and are hence found only in seedless vascular plants. Other parenchyma cells within the phloem are generally undifferentiated and used for food storage, although its primary function is transport of sugars, phloem may also contain cells that have a mechanical support function. These generally fall into two categories, fibres and sclereids, both cell types have a secondary cell wall and are therefore dead at maturity. The secondary cell wall increases their rigidity and tensile strength, bast fibres are the long, narrow supportive cells that provide tension strength without limiting flexibility. They are also found in xylem, and are the component of many textiles such as paper, linen. Sclereids are irregularly shaped cells that add compression strength but may reduce flexibility to some extent and they also serve as anti-herbivory structures, as their irregular shape and hardness will increase wear on teeth as the herbivores chew. For example, they are responsible for the gritty texture in pears, unlike xylem, the phloem is composed of still-living cells that transport sap. The sap is a solution, but rich in sugars made by photosynthesis. These sugars are transported to parts of the plant, such as the roots, or into storage structures
5.
Ground tissue
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The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three based on the nature of the cell walls. Parenchyma cells have thin walls and usually remain alive after they become mature. Parenchyma forms the tissue in the soft parts of plants. Collenchyma cells have thin walls with some areas of secondary thickening. Collenchyma provides extra support, particularly in regions of new growth. Sclerenchyma cells have thick lignified secondary walls and often die when mature, sclerenchyma provides the main structural support to a plant. Parenchyma is a versatile ground tissue that generally constitutes the filler tissue in parts of plants. It forms, among other things, the cortex and pith of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, parenchyma cells are living cells and may remain meristematic at maturity—meaning that they are capable of cell division if stimulated. They have thin but flexible cellulose cell walls, and are generally polyhedral when close-packed and they have large central vacuoles, which allow the cells to store and regulate ions, waste products, and water. Tissue specialised for food storage is commonly formed of parenchyma cells, chlorenchyma cells carry out photosynthesis and manufacture food. The shape of parenchyma cells varies with their function and these cells, along with the epidermal guard cells of the stoma, form a system of air spaces and chambers that regulate the exchange of gases. Shapes of parenchyma 1= polyhedral 2=stellate 3=elongated 4=lobed The first use of collenchyma was by Link who used it to describe the sticky substance on Bletia pollen, collenchyma tissue is composed of elongated cells with irregularly thickened walls. They provide structural support, particularly in growing shoots and leaves, collenchyma tissue makes up things such as the resilient strands in stalks of celery. Collenchyma cells are living, and have only a thick primary cell wall made up of cellulose. Cell wall thickness is strongly affected by mechanical stress upon the plant, the walls of collenchyma in shaken plants, may be 40–100% thicker than those not shaken. Sclerenchyma is the tissue in plants. Two types of sclerenchyma cells exist, fibres and sclereids and their cell walls consist of cellulose, hemicellulose and lignin
6.
Bast fibre
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Bast fibre is plant fibre collected from the phloem or bast surrounding the stem of certain dicotyledonous plants. They support the conductive cells of the phloem and provide strength to the stem, Bast fibres are classified as soft fibres, and are flexible. Fibres from monocotyledonous plants, called leaf fibre, are classified as hard fibres and are stiff, since the valuable fibres are located in the phloem, they must often be separated from the xylem material, and sometimes also from the epidermis. The process for this is called retting, and can be performed by micro-organisms either on land or in water, in the phloem, bast fibres occur in bundles that are glued together by pectin and calcium ions. More intense retting separates the fibre bundles into elementary fibres, that can be several centimetres long, often bast fibres have higher tensile strength than other kinds, and are used in high-quality textiles, ropes, yarn, paper, composite materials and burlap. An important property of bast fibres is that they contain a structure, the fibre node, that represents a weak point. Seed hairs, such as cotton, do not have nodes, from prehistoric times through at least the early 20th century, bast shoes were woven from bast strips in the forest areas of Eastern Europe. Where no other source of tanbark was available, bast has also used for tanning leather. International Jute Study Group Bast Fibre cords in Viking ships Bast fibre production with hemp
7.
Cortex (botany)
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A cortex is the outermost layer of a stem or root in a plant, or the surface layer or skin of the nonfruiting part of the body of some lichens. In botany, the cortex is the outermost layer of the stem or root of a plant, bounded on the outside by the epidermis, in plants, it is composed mostly of differentiated cells, usually large thin-walled parenchyma cells of the ground tissue system. The outer cortical cells often acquire irregularly thickened walls, and are called collenchyma cells. Some of the cortical cells may contain chloroplasts. It is responsible for the transportation of materials into the cylinder of the root through diffusion. On a lichen, the cortex is the skin, or outer layer of tissue that covers the undifferentiated cells of the medulla
8.
Greek language
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Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
9.
Leaf
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A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot, Leaves are collectively referred to as foliage, as in autumn foliage. Although leaves can be seen in different shapes, sizes and textures, typically a leaf is a thin, dorsiventrally flattened organ, borne above ground. Most leaves have distinctive upper surface and lower surface that differ in colour, hairiness, broad, flat leaves with complex venation are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In others, such as the clubmosses, with different evolutionary origins, some leaves, such as bulb scales are not above ground, and in many aquatic species the leaves are submerged in water. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls, furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes, and flattened leaf stems called phyllodes which differ from both in their structure and origin. Many structures of plants, such as the phyllids of mosses and liverworts and even of some foliose lichens. Leaves are the most important organs of most vascular plants and these are then further processed by chemical synthesis into more complex organic molecules such as cellulose, the basic structural material in plant cell walls. The plant must therefore bring these three together in the leaf for photosynthesis to take place. Once sugar has been synthesized, it needs to be transported to areas of growth such as the plant shoots and roots. Vascular plants transport sucrose in a tissue called the phloem. The phloem and xylem are parallel to each other but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch to form veins which supply as much as the leaf as possible and they are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance plants adapted to windy conditions may have pendent leaves, such as in many willows, the flat, or laminar, shape also maximises thermal contact with the surrounding air, promoting cooling. Functionally, in addition to photosynthesis the leaf is the site of transpiration and guttation. Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and these are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. For xerophytes the major constraint is not light flux or intensity, some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. and Bulbine mesembryanthemoides
