Virginia the Commonwealth of Virginia, is a state in the Southeastern and Mid-Atlantic regions of the United States located between the Atlantic Coast and the Appalachian Mountains. Virginia is nicknamed the "Old Dominion" due to its status as the first English colonial possession established in mainland North America and "Mother of Presidents" because eight U. S. presidents were born there, more than any other state. The geography and climate of the Commonwealth are shaped by the Blue Ridge Mountains and the Chesapeake Bay, which provide habitat for much of its flora and fauna; the capital of the Commonwealth is Richmond. The Commonwealth's estimated population as of 2018 is over 8.5 million. The area's history begins with several indigenous groups, including the Powhatan. In 1607 the London Company established the Colony of Virginia as the first permanent New World English colony. Slave labor and the land acquired from displaced Native American tribes each played a significant role in the colony's early politics and plantation economy.
Virginia was one of the 13 Colonies in the American Revolution. In the American Civil War, Virginia's Secession Convention resolved to join the Confederacy, Virginia's First Wheeling Convention resolved to remain in the Union. Although the Commonwealth was under one-party rule for nearly a century following Reconstruction, both major national parties are competitive in modern Virginia; the Virginia General Assembly is the oldest continuous law-making body in the New World. The state government was ranked most effective by the Pew Center on the States in both 2005 and 2008, it is unique in how it treats cities and counties manages local roads, prohibits its governors from serving consecutive terms. Virginia's economy has many sectors: agriculture in the Shenandoah Valley. S. Department of Defense and Central Intelligence Agency. Virginia has a total area of 42,774.2 square miles, including 3,180.13 square miles of water, making it the 35th-largest state by area. Virginia is bordered by Maryland and Washington, D.
C. to the north and east. Virginia's boundary with Maryland and Washington, D. C. extends to the low-water mark of the south shore of the Potomac River. The southern border is defined as the 36° 30′ parallel north, though surveyor error led to deviations of as much as three arcminutes; the border with Tennessee was not settled until 1893, when their dispute was brought to the U. S. Supreme Court; the Chesapeake Bay separates the contiguous portion of the Commonwealth from the two-county peninsula of Virginia's Eastern Shore. The bay was formed from the drowned river valleys of the James River. Many of Virginia's rivers flow into the Chesapeake Bay, including the Potomac, Rappahannock and James, which create three peninsulas in the bay; the Tidewater is a coastal plain between the fall line. It includes major estuaries of Chesapeake Bay; the Piedmont is a series of sedimentary and igneous rock-based foothills east of the mountains which were formed in the Mesozoic era. The region, known for its heavy clay soil, includes the Southwest Mountains around Charlottesville.
The Blue Ridge Mountains are a physiographic province of the Appalachian Mountains with the highest points in the state, the tallest being Mount Rogers at 5,729 feet. The Ridge and Valley region includes the Great Appalachian Valley; the region includes Massanutten Mountain. The Cumberland Plateau and the Cumberland Mountains are in the southwest corner of Virginia, south of the Allegheny Plateau. In this region, rivers flow northwest, into the Ohio River basin; the Virginia Seismic Zone has not had a history of regular earthquake activity. Earthquakes are above 4.5 in magnitude, because Virginia is located away from the edges of the North American Plate. The largest earthquake, at an estimated 5.9 magnitude, was in 1897 near Blacksburg. A 5.8 magnitude earthquake struck central Virginia on August 2011, near Mineral. The earthquake was felt as far away as Toronto and Florida. 35 million years ago, a bolide impacted. The resulting Chesapeake Bay impact crater may explain what earthquakes and subsidence the region does experience.
Coal mining takes place in the three mountainous regions at 45 distinct coal beds near Mesozoic basins. Over 64 million tons of other non-fuel resources, such as slate, sand, or gravel, were mined in Virginia in 2018; the state's carbonate rock is filled with more than 4,000 caves, ten of which are open for tourism, including the popular Luray Caverns and Skyline Caverns. The climate of Virginia is humid subtropical and becomes warmer and more humid farther south and east. Seasonal extremes vary from average lows of 26 °F in January to average highs of 86 °F in July; the Atlantic Ocean has a strong effect on southeastern coastal areas of the state. Influenced by the Gulf Stream, coastal weather is subject to hurricanes, most pronouncedly near the mouth of Chesapeake Bay. In spite of its position adjacent to the Atlantic Ocean the coastal areas have a significant continental influence with quite large temperature differences between summ
Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still used and is applied to plants collectively to refer to all edible plant matter, including the flowers, stems, leaves and seeds; the alternate definition of the term vegetable is applied somewhat arbitrarily by culinary and cultural tradition. It may exclude foods derived from some plants that are fruits and cereal grains, but include fruits from others such as tomatoes and courgettes and seeds such as pulses. Vegetables were collected from the wild by hunter-gatherers and entered cultivation in several parts of the world during the period 10,000 BC to 7,000 BC, when a new agricultural way of life developed. At first, plants which grew locally would have been cultivated, but as time went on, trade brought exotic crops from elsewhere to add to domestic types. Nowadays, most vegetables are grown all over the world as climate permits, crops may be cultivated in protected environments in less suitable locations.
China is the largest producer of vegetables and global trade in agricultural products allows consumers to purchase vegetables grown in faraway countries. The scale of production varies from subsistence farmers supplying the needs of their family for food, to agribusinesses with vast acreages of single-product crops. Depending on the type of vegetable concerned, harvesting the crop is followed by grading, storing and marketing. Vegetables can be eaten either raw or cooked and play an important role in human nutrition, being low in fat and carbohydrates, but high in vitamins and dietary fiber. Many nutritionists encourage people to consume plenty of fruit and vegetables, five or more portions a day being recommended; the word vegetable was first recorded in English in the early 15th century. It comes from Old French, was applied to all plants, it derives from Medieval Latin vegetabilis "growing, flourishing", a semantic change from a Late Latin meaning "to be enlivening, quickening". The meaning of "vegetable" as a "plant grown for food" was not established until the 18th century.
In 1767, the word was used to mean a "plant cultivated for food, an edible herb or root". The year 1955 saw the first use of the shortened, slang term "veggie"; as an adjective, the word vegetable is used in scientific and technical contexts with a different and much broader meaning, namely of "related to plants" in general, edible or not—as in vegetable matter, vegetable kingdom, vegetable origin, etc. The exact definition of "vegetable" may vary because of the many parts of a plant consumed as food worldwide—roots, leaves, flowers and seeds; the broadest definition is the word's use adjectivally to mean "matter of plant origin". More a vegetable may be defined as "any plant, part of, used for food", a secondary meaning being "the edible part of such a plant". A more precise definition is "any plant part consumed for food, not a fruit or seed, but including mature fruits that are eaten as part of a main meal". Falling outside these definitions are edible fungi and edible seaweed which, although not parts of plants, are treated as vegetables.
In the latter-mentioned definition of "vegetable", used in everyday language, the words "fruit" and "vegetable" are mutually exclusive. "Fruit" has a precise botanical meaning, being a part that developed from the ovary of a flowering plant. This is different from the word's culinary meaning. While peaches and oranges are "fruit" in both senses, many items called "vegetables", such as eggplants, bell peppers, tomatoes, are botanically fruits; the question of whether the tomato is a fruit or a vegetable found its way into the United States Supreme Court in 1893. The court ruled unanimously in Nix v. Hedden that a tomato is identified as, thus taxed as, a vegetable, for the purposes of the Tariff of 1883 on imported produce; the court did acknowledge, that, botanically speaking, a tomato is a fruit. Before the advent of agriculture, humans were hunter-gatherers, they foraged for edible fruit, stems, leaves and tubers, scavenged for dead animals and hunted living ones for food. Forest gardening in a tropical jungle clearing is thought to be the first example of agriculture.
Plant breeding through the selection of strains with desirable traits such as large fruit and vigorous growth soon followed. While the first evidence for the domestication of grasses such as wheat and barley has been found in the Fertile Crescent in the Middle East, it is that various peoples around the world started growing crops in the period 10,000 BC to 7,000 BC. Subsistence agriculture continues to this day, with many rural farmers in Africa, South America, elsewhere using their plots of land to produce enough food for their families, while any surplus produce is used for exchange for other goods. Throughout recorded history, the rich have been able to afford a varied diet including meat and fruit, but for poor people, meat was a luxury and the food they ate was dull comprising some staple product made from rice, barley, millet or maize; the addition of vegetable matter provided some variety to the diet. The staple diet of the Aztecs in Central America was maize and they cultivated tomatoes, beans, pumpkins, squashes and amaranth seeds to supplement their tortillas and porridge.
In Peru, the Incas subsisted on maize in the lowla
Chionanthus virginicus is a tree native to the savannas and lowlands of the southeastern United States, from New Jersey south to Florida, west to Oklahoma and Texas. It is a deciduous shrub or small tree growing to as much as 10 to 11 metres tall, though ordinarily less; the bark is brown tinged with red. The shoots are light green, downy at first becoming light brown or orange; the buds are light brown, acute, 3 millimetres long. The leaves are opposite, ovate or oblong, 7.5 to 20 centimetres long and 2.5 to 10 centimetres broad, with a petiole 2 centimetres long, an entire margin. The richly-scented flowers have a pure white four-lobed corolla, the lobes thread-like, 1.5 to 2.5 centimetres long and 3 millimetres broad. It is dioecious, though occasional plants bear flowers of both sexes; the fruit is an ovoid dark blue to purple drupe 1.5 to 2 centimetres long, containing a single seed, mature in late summer to mid fall. The species name was cited by Linnaeus as Chionanthus virginica, treating the genus as feminine.
Other English names used in the Appalachians include Grancy Gray Beard and Old Man's Beard. Although native in the southeastern United States, it is hardy in the north and is extensively planted in gardens, where specimens are grown with multiple trunks; the white flowers are best seen from below. Fall color is a good contrast with viburnums and evergreens, it prefers a sheltered situation. It may be propagated by grafting on Ash; the wood is light sapwood paler brown. The dried roots and bark were used by Native Americans to treat skin inflammations; the crushed bark was used in treatment of wounds. In 2014, white fringetrees in Ohio were reported to be hosting infestations of the emerald ash borer, an insect native to Asia that has become a destructive invasive pest of ash trees in North America. Since emerald ash borer has been found in white fringetrees in Illinois, Indiana and Pennsylvania, indicating to researchers that white fringetree is being utilized by emerald ash borer throughout the range where the species overlap.
Symptoms of infestation include crown dieback and epicormic sprouting
Davidia involucrata, the dove-tree, handkerchief tree, pocket handkerchief tree, or ghost tree, is a medium-sized deciduous tree in the family Nyssaceae. It was included with tupelos in the dogwood family, Cornaceae, it is native to South Central and Southwest China from Hubei to southern Gansu, south to Guizhou and Yunnan, but is cultivated elsewhere. Davidia involucrata is the only member of its genus, but there are two varieties differing in their leaves, D. involucrata var. involucrata, which has the leaves thinly pubescent on the underside, D. involucrata var. vilmoriniana, with glabrous leaves. Some botanists treat them as distinct species, with good reason, as the two taxa have differing chromosome numbers so are unable to produce fertile hybrid offspring, it is a moderately fast-growing tree, growing to 20–25 m in height, with alternate cordate leaves resembling those of a linden in appearance, except that they are symmetrical, lacking the lop-sided base typical of linden leaves. Davidia involucrata is best known for its flowers.
The Latin specific epithet involucrata means "with a ring of bracts surrounding several flowers". These form a tight cluster about 1–2 cm across, reddish in colour, each flower head with a pair of large, pure white bracts at the base performing the function of petals; these hang in long rows beneath the level branches. The flowers are at their best in late May. On a breezy day, the bracts flutter in the wind like white doves or pinched handkerchiefs, hence the English names for this tree; the fruit is a hard nut about 3 cm long surrounded by a green husk about 4 cm long by 3 cm wide, hanging on a 10 cm stalk. The nut contains 3–6 seeds; the genus Davidia is named for Father Armand David, a French Vincentian missionary and keen naturalist who lived in China. David first described the tree in 1869 as a single tree found at over 2,000 m altitude, sent dried specimens to Paris. Scottish plant hunter Augustine Henry again found a single tree, this time in the Yangtse Ichang gorges and sent the first specimen to Kew Gardens.
Plant collector Ernest Henry Wilson was employed by Sir Harry Veitch to find Henry's tree but arrived to find that it had been felled for building purposes. Returning to England, Wilson had his boat managed to save his Davidia specimens; the oldest probable fossils of Davidia are permineralized fruits from the Upper Cretaceous Horseshoe Canyon Formation of Dinosaur Provincial Park near Drumheller, Canada. Those fruits are smaller than those of D. involucrata and have fewer locules, but are otherwise similar in morphology to the extant genus. In 2009, B. I. Pavlyutkin described Miocene fossils in Primorsky Krai and assigned them to a new species in the genus Davidia; the species was introduced from China to Europe and North America in 1904, is a popular ornamental tree in parks and larger gardens. Most trees in cultivation are var. vilmoriniana, which has proved much better able to adapt to the climatic conditions in the west. This tree and the cultivated variety D. involucrata var. vilmoriniana have gained the Royal Horticultural Society's Award of Garden Merit.
Media related to Davidia involucrata at Wikimedia Commons
Betula nigra, the black birch, river birch or water birch, is a species of birch native to the Eastern United States from New Hampshire west to southern Minnesota, south to northern Florida and west to Texas. It is one of the few heat-tolerant birches in a family of cold-weather trees which do not thrive in USDA Zone 6 and up. B. nigra occurs in floodplains and swamps. Betula nigra is a deciduous tree growing to 25–30 meters with a trunk 50 to 150 centimeters in diameter; the base of the tree is divided into multiple slender trunks. Bark Bark characteristics of the river birch differ during its youth stage and old growth; the bark of a young river birch can vary from having a salmon-pink to brown-gray tint and can be described as having loose layers of curling, paper thin scales. As the tree matures, the salmon-pink color is exchanged for a reddish-brown with a dark grey base color; the scales on a mature tree lack the loose curling and are pressed into thick, irregular plates. These scales are separated from the trunk and can shift outward to the side.
Once the River Birch ages past maturity, the scales become thicker towards the base of the trunk and are divided in deep furrows. Leaves and Fruit The twigs are thinly hairy. There is an absence of terminal buds, lateral buds have a hook at the tip of the bud, which differs from other species in the family Betulaceae; the leaves are alternate, ovate, 4–8 centimeters long and 3–6 centimeters broad, with a serrated margin and five to twelve pairs of veins. The upper surface of the leaf is dark green in color, while the underside can be described as having a light yellow-green color; the flowers are wind-pollinated catkins 3–6 centimeters long, the male catkins pendulous, the female catkins erect. The fruit is unusual among birches in maturing in late spring. Betula nigra is a tree that falls into the family of Betulaceae, known as the Birch or Alder Family; this family comprises six genera and includes alders, birches and hazelnuts. Species within this family, along with Betula nigra, are shrubs or trees that grow along stream sides or in poorly drained soils throughout the Northern Hemisphere.
Betulaceae is included within the order Fagales. The river birch is found in low-elevation regions from as north as Massachusetts to as south as northern Florida, it can be found extending west to Kansas and east to the coast where proper habitat conditions occur. As its name depicts, this birch is found along stream-sides, it can be a prominent species found in forested wetland communities and in areas containing moist soil, such as floodplains. States include: Alabama, Connecticut, Florida, Illinois, Iowa, Kentucky, Maryland, Missouri, New Hampshire, New Jersey, New York, North Carolina, Oklahoma, South Carolina, Texas, West Virginia, Wisconsin, it is listed as threatened in New Hampshire. In states in which mining is prevalent, the river birch is used for reclamation and erosion control, as it is well suited for soils that are too acidic for other species of hardwoods. In West Virginia, they have been found to establish within mine refuge sites after being blown from neighboring areas; as the species occurs predominately in flood plains and along stream banks, it is described as being moderately tolerant of flooding.
Saplings were observed to survive up to 30 days of continuous flooding in some regions. While the species is tolerant of excessive water, it is intolerant of shade. Seeds will not germinate without a large amount of direct sunlight. Seeds are produced annually. Seasonal development begins in the fall as male catkins begin to mature; the emergence of female catkins corresponds with the return of leaves around early spring. Male and female fruit matures in the early summer months. Once mature, the seeds are predominantly spread by wind of water from neighboring stream channels. Seeds spread by water are more successful as the moist banks of stream channels, where the seeds are deposited, are favorable for germination and sturdy establishment. Successful germination occurs in large numbers along sandbars, where alluvial soil is present. While its native habitat is wet ground, it will grow on higher land, its bark is quite distinctive, making it a favored ornamental tree for landscape use. A number of cultivars with much whiter bark than the normal wild type have been selected for garden planting, including'Heritage' and'Dura Heat'.
Native Americans used the boiled sap as a sweetener similar to maple syrup, the inner bark as a survival food. The river birch is not used in the commercial lumber industry, due to knotting, but its strong grained wood is sometimes used for local furniture and fuel; this species is utilized by many local bird species, such as waterfowl, ruffed grouse, wild turkey. Many waterfowl use the cover for nesting sites, while the ruffed grouse and wild turkey use the seeds as a food source. Deer have been known to graze on saplings or reachable branches; the essential oils derived from leaves, inner bark, buds of B. nigra are composed of eugenol, palmitic acid, heptacosane with many more compounds in smaller concentrations. The combined essential
Lewis and Clark Expedition
The Lewis and Clark Expedition from May 1804 to September 1806 known as the Corps of Discovery Expedition, was the first American expedition to cross the western portion of the United States. It began in Pittsburgh, Pa, made its way westward, passed through the Continental Divide of the Americas to reach the Pacific coast; the Corps of Discovery was a selected group of US Army volunteers under the command of Captain Meriwether Lewis and his close friend Second Lieutenant William Clark. President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, to establish an American presence in this territory before Britain and other European powers tried to claim it; the campaign's secondary objectives were scientific and economic: to study the area's plants, animal life, geography, to establish trade with local American Indian tribes. The expedition returned to St. Louis to report its findings to Jefferson, with maps and journals in hand.
One of Thomas Jefferson's goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, getting an accurate sense of the resources in the completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission. During the 19th century, references to Lewis and Clark "scarcely appeared" in history books during the United States Centennial in 1876, the expedition was forgotten. Lewis and Clark began to gain attention around the start of the 20th century. Both the 1904 Louisiana Purchase Exposition in St. Louis and the 1905 Lewis and Clark Centennial Exposition in Portland, Oregon showcased them as American pioneers. However, the story remained shallow until mid-century as a celebration of US conquest and personal adventures, but more the expedition has been more researched.
In 2004, a complete and reliable set of the expedition's journals was compiled by Gary E. Moulton. In the 2000s, the bicentennial of the expedition further elevated popular interest in Lewis and Clark; as of 1984, no US exploration party was more famous, no American expedition leaders are more recognizable by name. Jefferson met John Ledyard in Paris in the 1780s, they discussed a possible trip to the Pacific Northwest. Jefferson had read Captain James Cook's A Voyage to the Pacific Ocean, an account of Cook's third voyage, Le Page du Pratz's The History of Louisiana, all of which influenced his decision to send an expedition. Like Captain Cook, he wished to discover a practical route through the Northwest to the Pacific coast. Alexander Mackenzie had charted a route in his quest for the Pacific, following the Mackenzie River to the Arctic Ocean in 1789. Mackenzie and his party were the first to cross America north of Mexico to the Pacific when he arrived near Bella Coola, British Columbia in 1793—a dozen years before Lewis and Clark.
Mackenzie's accounts in Voyages from Montreal informed Jefferson of Britain's intent to control the lucrative fur trade of the Columbia River and convinced him of the importance of securing the territory as soon as possible. Two years into his presidency, Jefferson asked Congress to fund an expedition through the Louisiana territory to the Pacific Ocean, he did not attempt to make a secret of the Lewis and Clark expedition from Spanish and British officials, but rather claimed different reasons for the venture. He used a secret message to ask for funding due to poor relations with the opposition Federalist Party in Congress. In 1803, Jefferson commissioned the Corps of Discovery and named Army Captain Meriwether Lewis its leader, who selected William Clark as second in command. Lewis demonstrated remarkable skills and potential as a frontiersman, Jefferson made efforts to prepare him for the long journey ahead as the expedition was gaining approval and funding. Jefferson explained his choice of Lewis: It was impossible to find a character who to a complete science in botany, natural history, mineralogy & astronomy, joined the firmness of constitution & character, habits adapted to the woods & a familiarity with the Indian manners and character, requisite for this undertaking.
All the latter qualifications Capt. Lewis has. In 1803, Jefferson sent Lewis to Philadelphia to study medicinal cures under Benjamin Rush, a physician and humanitarian, he arranged for Lewis to be further educated by Andrew Ellicott, an astronomer who instructed him in the use of the sextant and other navigational instruments. Lewis, was not ignorant of science and had demonstrated a marked capacity to learn with Jefferson as his teacher. At Monticello, Jefferson possessed the largest library in the world on the subject of the geography of the North American continent, Lewis had full access to it, he spent time conferring with Jefferson. Lewis and Clark met near Louisville, Kentucky in October 1803 at the Falls of the Ohio and the core "Nine Young Men" were enlisted into the Corps of Discovery, their goals were to explore the vast territory acquired by the Louisiana Purchase and to establish trade and US sovereignty over the Indians along the Missouri River. Jefferson wanted to establish a US claim of "discovery" to the Pacific Northwest and Oregon territory by documenting an American presence there before European nations could claim the land.
According to some historians, Jefferson understood that he would have
Poaceae or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses referred to collectively as grass. Poaceae includes the cereal grasses and the grasses of natural grassland and cultivated lawns and pasture. Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks; the lower part of each leaf encloses the stem. With around 780 genera and around 12,000 species, Poaceae are the fifth-largest plant family, following the Asteraceae, Orchidaceae and Rubiaceae. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica. Grasses are an important part of the vegetation in many other habitats, including wetlands and tundra; the Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize, rice and millet as well as forage, building materials and fuel.
Though they are called "grasses", seagrasses and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales; the name Poaceae was given by John Hendley Barnhart in 1895, based on the tribe Poeae described in 1814 by Robert Brown, the type genus Poa described in 1753 by Carl Linnaeus. The term is derived from the Ancient Greek πόα. Grasses include some of the most versatile plant life-forms, they became widespread toward the end of the Cretaceous period, fossilized dinosaur dung have been found containing phytoliths of a variety that include grasses that are related to modern rice and bamboo. Grasses have adapted to conditions in lush rain forests, dry deserts, cold mountains and intertidal habitats, are the most widespread plant type. A cladogram shows subfamilies and approximate species numbers in brackets: Before 2005, fossil findings indicated that grasses evolved around 55 million years ago.
Recent findings of grass-like phytoliths in Cretaceous dinosaur coprolites have pushed this date back to 66 million years ago. In 2011, revised dating of the origins of the rice tribe Oryzeae suggested a date as early as 107 to 129 Mya. Wu, You & Li described grass microfossils extracted from a specimen of the hadrosauroid dinosaur Equijubus normani from the Early Cretaceous Zhonggou Formation; the authors noted that India became separated from Antarctica, therefore all other continents at the beginning of late Aptian, so the presence of grasses in both India and China during the Cretaceous indicates that the ancestor of Indian grasses must have existed before late Aptian. Wu, You & Li considered the Barremian origin for grasses to be probableThe relationships among the three subfamilies Bambusoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more related to each other than to Oryzoideae; this separation occurred within the short time span of about 4 million years.
According to Lester Charles King the spread of grasses in the Late Cenozoic would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a free face were common. King argued that this was the result of more acting surface wash caused by carpets of grass which in turn would have resulted in more soil creep. Grasses may be annual or perennial herbs with the following characteristics: The stems of grasses, called culms, are cylindrical and are hollow, plugged at the nodes, where the leaves are attached. Grass leaves are nearly always alternate and distichous, have parallel veins; each leaf is differentiated into a lower sheath hugging a blade with entire margins. The leaf blades of many grasses are hardened with silica phytoliths, which discourage grazing animals. A membranous appendage or fringe of hairs called the ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath. Flowers of Poaceae are characteristically arranged in each having one or more florets.
The spikelets are further grouped into spikes. The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two bracts at called glumes, followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea; the flowers are hermaphroditic—maize being an important exception—and anemophilous or wind-pollinated, although insects play a role. The perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea; this complex structure can be seen in the image on the right. The fruit of grasses is a caryopsis. A tiller is a leafy shoot other than the first shoot produced from the seed. Grass blades grow at the base of the blade and not from elongated stem tips; this low growth point evolved in response to grazing animals and allows grasses to be grazed or mown without severe damage to the plant. Three general classifications of growth habit present in g