1.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Plant
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Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
3.
Flowering plant
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The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c.295,383 known species, etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant. The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range 245 to 202 million years ago, and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, 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 xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very 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, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and 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, and 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 on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule. The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals. The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower
4.
Monocotyledon
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Monocotyledons, commonly referred to as monocots, are flowering plants whose seeds typically contain only one embryonic leaf, or cotyledon. However, molecular research has shown that while the monocots form a monophyletic group or clade. Monocots have almost always recognized as a group, but with various taxonomic ranks. The APG III system of 2009 recognises a clade called monocots, the monocots include about 60,000 species. The largest family in this group by number of species are the orchids, about half as many species belong to the true grasses, which are economically the most important family of monocots. In agriculture the majority of the biomass produced comes from monocots and these include not only major grains, but also forage grasses, sugar cane, and the bamboos. Other economically important monocot crops include various palms, bananas, gingers and their relatives, turmeric and cardamom, asparagus and the onions and garlic family. Additionally most of the bulbs, plants cultivated for their blooms, such as lilies, daffodils, irises, amaryllis, cannas, bluebells. The monocots or monocotyledons have, as the name implies, a single cotyledon, or embryonic leaf, from a diagnostic point of view the number of cotyledons is neither a particularly useful characteristic, nor is it completely reliable. Nevertheless, monocots are sufficiently distinctive that there has rarely been disagreement as to membership of this group, however, morphological features that reliably characterise major clades are rare. Thus monocots are distinguishable from other angiosperms both in terms of their uniformity and diversity, although largely herbaceous, some arboraceous monocots reach great height, length and mass. The latter include agaves, palms, pandans, and bamboos and this creates challenges in water transport that monocots deal with in various ways. Some such as species of Yucca develop anomalous secondary growth, while palm trees, the axis undergoes primary thickening, that progresses from internode to internode, resulting in a typical inverted conical shape of the basal primary axis. The limited conductivity also contributes to limited branching of the stems, despite these limitations a wide variety of adaptive growth forms has resulted from epiphytic orchids and bromeliads to submarine Alismatales and mycotrophic Burmanniaceae and Triuridaceae. Other monocots, particularly Poales have adopted a life form. Leaves The cotyledon, the primordial Angiosperm leaf consists of a proximal leaf base or hypophyll, in moncots the hypophyll tends to be the dominant part in contrast to other angiosperms. Mature monocot leaves are narrow and linear, forming a sheathing around the stem at its base. There is usually only one leaf per node because the leaf base encompasses more than half the circumference, the evolution of this monocot characteristic has been attributed to developmental differences in early zonal differentiation rather than meristem activity
5.
Asparagales
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Asparagales is an order of plants in modern classification systems such as the Angiosperm Phylogeny Group and the Angiosperm Phylogeny Web. The order takes its name from the type family Asparagaceae and is placed in the monocots amongst the lilioid monocots, the order has only recently been recognized in classification systems. It was first put forward by Huber in 1977 and later taken up in the Dahlgren system of 1985 and then the APG in 1998,2003 and 2009. Before this, many of its families were assigned to the old order Liliales, DNA sequence analysis indicated that many of the taxa previously included in Liliales should actually be redistributed over three orders, Liliales, Asparagales and Dioscoreales. The boundaries of the Asparagales and of its families have undergone a series of changes in recent years, future research may lead to further changes and ultimately greater stability. In the APG circumscription, Asparagales is the largest order of monocots with 14 families,1,122 genera, the order is clearly circumscribed on the basis of molecular phylogenetics, but is difficult to define morphologically, since its members are structurally diverse. Most species of Asparagales are herbaceous perennials, although some are climbers, the order also contains many geophytes. According to telomere sequence, at least two evolutionary switch-points happened within the order, basal sequence is formed by TTTAGGG like in majority of higher plants. Basal motif was changed to vertebrate-like TTAGGG and finally the most divergent motif CTCGGTTATGGG appears in Allium, one of the defining characteristics of the order is the presence of phytomelanin, a black pigment present in the seed coat, creating a dark crust. Phytomelanin is found in most families of the Asparagales, the leaves of almost all species form a tight rosette, either at the base of the plant or at the end of the stem, but occasionally along the stem. The flowers are not particularly distinctive, being lily type, with six tepals, from an economic point of view, the order Asparagales is second in importance within the monocots to the order Poales. Species are used as food and flavourings, as cut flowers, and as garden ornamentals. Thus although most species in the order are herbaceous, some no more than 15 cm high, there are a number of climbers, as well as several genera forming trees, succulent genera occur in several families. Almost all species have a cluster of leaves, either at the base of the plant or at the end of a more-or-less woody stem as with Yucca. In some cases the leaves are produced along the stem, the flowers are in the main not particularly distinctive, being of a general lily type, with six tepals, either free or fused from the base and up to six stamina. They are frequently clustered at the end of the plant stem and they are generally geophytes, but with linear leaves, and a lack of fine reticular venation. The seeds characteristically have the external epidermis either obliterated, or if present, have a layer of black carbonaceous phytomelanin in species with dry fruits. The inner part of the coat is generally collapsed, in contrast to Liliales whose seeds have a well developed outer epidermis, lack phytomelanin
6.
Dracaena (plant)
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Dracaena Dracaena arborea – tree dracaena Dracaena aubryana Brongn. – ribbon dracaena, marketed as lucky bamboo Dracaena camerooniana Baker Dracaena cincta Dracaena cinnabari Balf. f, – Socotra dragon tree Dracaena concinna Kunth Dracaena draco L. – Canary Islands dragon tree Dracaena ellenbeckiana - Kedong Dracaena Dracaena elliptica Dracaena fragrans Ker Gawl. – Pleomele dracaena or Song of India Dracaena serrulata Baker – Yemen dragon tree Dracaena surculosa Lindl, – spotted or gold dust dracaena. Formerly D. godseffiana Dracaena tamaranae – Gran Canaria dragon tree Dracaena umbraculifera Jacq, asparagus asparagoides Druce Cordyline australis Endl. Cordyline obtecta Baker Cordyline stricta Endl, liriope graminifolia Baker Lomandra filiformis Britten Some shrubby species, such as D. deremensis, D. fragrans, D. godseffiana, D. marginata, and D. braunii, are popular as houseplants. Many of these are toxic to pets, though not humans, rooted stem cuttings of D. braunii are widely marketed in the U. S. A. and the UK as lucky bamboo, although only superficially resembling true bamboos. A bright red resin, dragons blood, is produced from D. draco and, in ancient times, modern dragons blood is however more likely to be from the unrelated Daemonorops rattan palms. Media related to Dracaena at Wikimedia Commons Data related to Dracaena at Wikispecies Socotra botany
7.
Socotra
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Socotra, also spelled Soqotra, is an island and a small archipelago of four islands in the Arabian Sea. The territory is part of Yemen, and had long been a subdivision of the Aden Governorate, in 2004, it became attached to the Hadhramaut Governorate, which is much closer to the island than Aden. In 2013, the archipelago became its own governorate, the Soqatra Governorate, the island of Socotra constitutes around 95% of the landmass of the archipelago. It lies some 240 kilometres east of the Horn of Africa and 380 kilometres south of the Arabian Peninsula, the island is very isolated and a third of its plant life is found nowhere else on the planet. It has been described as the most alien-looking place on Earth, the island measures 132 kilometres in length and 49.7 kilometres in width. In the notes to his translation of the Periplus of the Erythraean Sea, huntingford remarks that the name Suqotra is not Greek in origin, but from the Sanskrit dvīpa sukhadhara. Another posited origin of the name is the Arabic suq meaning market, there was initially an Oldowan culture in Socotra. Oldowan stone tools were found in the area around Hadibo by V. A, zhukov, a member of the Russian Complex Expedition in 2008. Socotra appears as Dioskouridou in the Periplus of the Erythraean Sea, in 2001 a group of Belgian speleologists of the Socotra Karst Project investigated a cave on the island Socotra. There, they came across a number of inscriptions, drawings. Further investigation showed that these had left by sailors who visited the island between the 1st century BC and the 6th century AD. Most of the texts are written in the Indian Brāhmī script and this corpus of nearly 250 texts and drawings thus constitutes one of the main sources for the investigation of Indian Ocean trade networks in that time period. A local tradition holds that the inhabitants were converted to Christianity by Thomas the Apostle in AD52, in the 10th century, the Arab geographer Abu Muhammad al-Hasan al-Hamdani stated that in his time most of the inhabitants were Christians. They were Nestorians but also practised ancient magic rituals despite the warnings of their archbishop and he reported in a letter home that the tribesmen, due to lack of missionaries, had only retained a faint knowledge of Christianity. In 1507, a Portuguese fleet commanded by Tristão da Cunha with Afonso de Albuquerque landed at the capital of Suq. Their objective was to set a base in a place on the route to India. Tomás Fernandes started to build a fortress at Suq, the Forte de São Miguel de Socotorá, however, the infertility of the land led to famine and sickness in the garrison. Thus the Portuguese abandoned the island four years later, as it was not advantageous as a base, the islands passed under the control of the Mahra sultans in 1511, and its inhabitants were completely Islamized during their rule
8.
Yemen
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Yemen, officially known as the Republic of Yemen, is an Arab country in Western Asia, occupying South Arabia, the southern end of the Arabian Peninsula. Yemen is the second-largest country in the peninsula, occupying 527,970 km2, the coastline stretches for about 2,000 km. It is bordered by Saudi Arabia to the north, the Red Sea to the west, the Gulf of Aden and Arabian Sea to the south, although Yemens constitutionally stated capital is the city of Sanaa, the city has been under rebel control since February 2015. Because of this, Yemens capital has been relocated to the port city of Aden. Yemens territory includes more than 200 islands, the largest of these is Socotra, Yemen was the home of the Sabaeans, a trading state that flourished for over a thousand years and probably also included parts of modern-day Ethiopia and Eritrea. In 275 AD, the region came under the rule of the later Jewish-influenced Himyarite Kingdom, Christianity arrived in the fourth century, whereas Judaism and local paganism were already established. Islam spread quickly in the century and Yemenite troops were crucial in the expansion of the early Islamic conquests. Administration of Yemen has long been notoriously difficult, several dynasties emerged from the ninth to 16th centuries, the Rasulid dynasty being the strongest and most prosperous. The country was divided between the Ottoman and British empires in the twentieth century. The Zaydi Mutawakkilite Kingdom of Yemen was established after World War I in North Yemen before the creation of the Yemen Arab Republic in 1962, South Yemen remained a British protectorate known as the Aden Protectorate until 1967 when it became an independent state and later, a Marxist state. The two Yemeni states united to form the modern republic of Yemen in 1990, Yemen is a developing country, and the poorest country in the Middle East. Under the rule of President Ali Abdullah Saleh, Yemen was described as a kleptocracy, according to the 2009 international corruption Perception Index by Transparency International, Yemen ranked 164 out of 182 countries surveyed. President Saleh stepped down and the powers of the presidency were transferred to Vice President Abd Rabbuh Mansur Hadi, the transitional process was disrupted by conflicts between the Houthis and al-Islah, as well as the al-Qaeda insurgency. In September 2014, the Houthis took over Sanaa, later declaring themselves in control of the government in a coup détat, since then, a Saudi-led intervention has taken place, however, it could not stop the civil war. Instead, the Saudis and the others have destroyed some hospitals, schools and homes, Yemen was mentioned in Old South Arabian inscriptions as Yamnat. In Arabic literature, the term includes much greater territory than that of the republic of Yemen. It stretches from the northern Asir Region in southwestern Saudi Arabia to Dhofar Governorate in southern Oman, one etymology derives Yemen from yumn, meaning felicity, as much of the country is fertile. The Romans called it Arabia Felix, as opposed to Arabia Deserta, al-Yaman significantly plays on the notion of the land to the right, when in Mecca facing the dawn, complementary to Al-Sham, the Land to the Left, referring to the Levant
9.
Arabian Sea
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The Arabian Sea is a region of the northern Indian Ocean bounded on the north by Pakistan and Iran, on the west by northeastern Somalia and the Arabian Peninsula, and on the east by India. Historically the sea has been known by names including the Erythraean Sea. Its total area is 3,862,000 km2 and its depth is 4,652 metres. The Gulf of Aden is in the southwest, connecting the Arabian Sea to the Red Sea through the strait of Bab-el-Mandeb, the Arabian Sea has been crossed by important marine trade routes since the third or second millennium BCE. Major seaports include Jawaharlal Nehru Port in Mumbai, the Port of Karachi and the Gwadar Port in Pakistan, other important ports include in India, Kandla Port, and Mormugao in Goa. The largest islands in the Arabian Sea include Socotra, Masirah Island, Astola Island, the Arabian Seas surface area is about 3,862,000 km2. The maximum width of the Sea is approximately 2,400 km, the biggest river flowing into the Sea is the Indus River. There are also the gulfs of Khambhat and Kutch on the Indian coast, the countries with coastlines on the Arabian Sea are Somalia, Djibouti, Yemen, Oman, United Arab Emirates, Iran, Pakistan, India and the Maldives. There are several cities on the seas coast including Mumbai, Surat, Karachi, Gwadar, Pasni, Ormara, Aden, Muscat, Keti Bandar, Salalah, Duqm. International Hydrographic Organization defines the limits of the Arabian Sea as follows, the Eastern limit of the Gulf of Aden. A line joining Ràs al Hadd, East point of Arabia, a line running from the South extremity of Addu Atoll, to the Eastern extreme of Ràs Hafun. The Western limit of the Laccadive Sea, by the time of Julius Caesar, several well-established combined land-sea trade routes depended upon water transport through the Sea around the rough inland terrain features to its north. Each major route involved transhipping to pack animal caravan, travel through country and risk of bandits. Later the kingdom of Axum arose in Ethiopia to rule a mercantile empire rooted in the trade with Europe via Alexandria, Jawaharlal Nehru Port in Mumbai is the largest port in the Arabian Sea, and the largest container port in India. The Port of Karachi is Pakistans largest and busiest seaport, handling about 60% of the nations cargo and it is located between the Karachi towns of Kiamari and Saddar, close to the main business district and several industrial areas. The geographic position of the places it in close proximity to major shipping routes such as the Strait of Hormuz. The history of the port is intertwined with that of the city of Karachi, several ancient ports have been attributed in the area including Krokola, Morontobara, Barbarikon (the Periplus of the Erythraean Sea, and Debal. It warns sailors about whirlpools and advises them to safety in Kaurashi harbour if they found themselves drifting dangerously
10.
Dendrochronology
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Dendrochronology is the scientific method of dating tree rings to the exact year they were formed in order to analyze atmospheric conditions during different periods in history. Dendrochronology is useful for determining the timing of events and rates of change in the environment and also in works of art and architecture, such as old panel paintings on wood, buildings and it is also used in radiocarbon dating to calibrate radiocarbon ages. New growth in trees occurs in a layer of cells near the bark, a trees growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings. Each ring marks a complete cycle of seasons, or one year, as of 2013, the oldest tree-ring measurements in the Northern Hemisphere extend back 13,900 years. Dendrochronology derives from Ancient Greek, δένδρον, meaning tree limb, χρόνος, meaning time, and -λογία, the Greek botanist Theophrastus first mentioned that the wood of trees has rings. In his Trattato della Pittura, Leonardo da Vinci was the first person to mention that trees form rings annually, in 1737, French investigators Henri-Louis Duhamel du Monceau and Georges-Louis Leclerc de Buffon examined the effect of growing conditions on the shape of tree rings. They found that in 1709, a severe winter produced a distinctly dark tree ring, the English polymath Charles Babbage proposed using dendrochronology to date the remains of trees in peat bogs or even in geological strata. During the latter half of the century, the scientific study of tree rings. In 1859, the German-American Jacob Kuechler used crossdating to examine oaks in order to study the record of climate in western Texas, in 1866, the German botanist, entomologist, and forester Julius Ratzeburg observed the effects on tree rings of defoliation caused by insect infestations. By 1882, this observation was already appearing in forestry textbooks, in the 1870s, the Dutch astronomer Jacobus C. Kapteyn was using crossdating to reconstruct the climates of the Netherlands, in 1881, the Swiss-Austrian forester Arthur von Seckendorff-Gudent was using crossdating. From 1869 to 1901, Robert Hartig, a German professor of forest pathology, wrote a series of papers on the anatomy, in 1892, the Russian physicist Fedor Nikiforovich Shvedov wrote that he had used patterns found in tree rings to predict droughts in 1882 and 1891. During the first half of the 20th century, the astronomer A. E. Douglass founded the Laboratory of Tree-Ring Research at the University of Arizona. Growth rings, also referred to as tree rings or annual rings, growth rings are the result of new growth in the vascular cambium, a layer of cells near the bark that is classified as a lateral meristem, this growth in diameter is known as secondary growth. Visible rings result from the change in speed through the seasons of the year, thus, critical for the title method. If the bark of the tree has been removed in a particular area, the rings are more visible in temperate zones, where the seasons differ more markedly. The inner portion of a ring is formed early in the growing season, when growth is comparatively rapid and is known as early wood. Many trees in temperate zones make one growth ring each year, hence, for the entire period of a trees life, a year-by-year record or ring pattern is formed that reflects the age of the tree and the climatic conditions in which the tree grew
11.
Seed dispersal
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Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have very limited mobility and consequently rely upon a variety of vectors to transport their propagules. Seeds can be dispersed away from the parent plant individually or collectively, there are five main modes of seed dispersal, gravity, wind, ballistic, water, and by animals. Some plants are serotinous and only disperse their seeds in response to an environmental stimulus, seed dispersal is likely to have several benefits for plant species. First, seed survival is often away from the parent plant. This higher survival may result from the actions of density-dependent seed and seedling predators and pathogens, competition with adult plants may also be lower when seeds are transported away from their parent. Seed dispersal also allows plants to reach specific habitats that are favorable for survival, for example, Ocotea endresiana is a tree species from Latin America which is dispersed by several species of birds, including the three-wattled bellbird. In the case of fleshy-fruited plants, seed-dispersal in animal guts often enhances the amount, the speed, and the asynchrony of germination, seeds dispersed by ants are not only dispersed short distances but are also buried underground by the ants. These seeds can thus avoid adverse effects such as fire or drought, reach nutrient-rich microsites. These features are peculiar to myrmecochory, which may provide additional benefits not present in other dispersal modes. Finally, at scale, seed dispersal may allow plants to colonize vacant habitats. In fact, recent evidence suggests that the majority of seed dispersal events involves more than one dispersal phase, seed dispersal is sometimes split into autochory and allochory. Autochorous plants disperse their seed without any help from an external vector, two other types of autochory not described in detail here are blastochory, where the stem of the plant crawls along the ground to deposit its seed far from the base of the plant, and herpochory. Barochory or the plant use of gravity for dispersal is a means of achieving seed dispersal. The effect of gravity on heavier fruits causes them to fall from the plant when ripe, fruits exhibiting this type of dispersal include apples, coconuts and passionfruit and those with harder shells. Gravity dispersal also allows for transmission by water or animal. Ballochory is a type of dispersal where the seed is ejected by explosive dehiscence of the fruit. Often the force that generates the results from turgor pressure within the fruit or due to internal tensions within the fruit
12.
Arecaceae
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The Arecaceae are a botanical family of perennial climbers, shrubs, acaules and trees commonly known as palm trees. They are flowering plants, a family in the monocot order Arecales, currently 181 genera with around 2600 species are known, most of them restricted to tropical, subtropical, and warm temperate climates. Most palms are distinguished by their large, compound, evergreen leaves, known as fronds, however, palms exhibit an enormous diversity in physical characteristics and inhabit nearly every type of habitat within their range, from rainforests to deserts. Palms are among the best known and most extensively cultivated plant families and they have been important to humans throughout much of history. Many common products and foods are derived from palms, and palms are widely used in landscaping, making them one of the most economically important plants. In many historical cultures, palms were symbols for such ideas as victory, peace, for inhabitants of cooler climates today, palms symbolize the tropics and vacations. Whether as shrubs, trees, or vines, palms have two methods of growth, solitary or clustered, the common representation is that of a solitary shoot ending in a crown of leaves. This monopodial character may be exhibited by prostrate, trunkless, some common palms restricted to solitary growth include Washingtonia and Roystonea. Palms may instead grow in sparse though dense clusters, the trunk develops an axillary bud at a leaf node, usually near the base, from which a new shoot emerges. The new shoot, in turn, produces an axillary bud, exclusively sympodial genera include many of the rattans, Guihaia, and Rhapis. Several palm genera have both solitary and clustering members, Palms which are usually solitary may grow in clusters, and vice versa. These aberrations suggest the habit operates on a single gene, Palms have large, evergreen leaves that are either palmately or pinnately compound and spirally arranged at the top of the stem. The leaves have a sheath at the base that usually splits open on one side at maturity. The inflorescence is a spadix or spike surrounded by one or more bracts or spathes that become woody at maturity, the flowers are generally small and white, radially symmetric, and can be either uni- or bisexual. The sepals and petals usually number three each, and may be distinct or joined at the base, the stamens generally number six, with filaments that may be separate, attached to each other, or attached to the pistil at the base. The fruit is usually a single-seeded drupe but some genera may contain two or more seeds in each fruit, like all monocots, palms do not have the ability to increase the width of a stem via the same kind of vascular cambium found in non-monocot woody plants. This explains the shape of the trunk that is often seen in palms. The Arecaceae are notable among monocots for their height and for the size of their seeds, leaves, Ceroxylon quindiuense, Colombias national tree, is the tallest monocot in the world, reaching up to 60 m tall
