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Sugar Maple

Sugar Maple

The Sugar Maple Acer saccharum is a prominent tree in the hardwood forests of eastern North America. It is the largest American maple, reaching heights of 30-37 m tall. maple The leaves are deciduous, 8-15 cm long and equally wide with five palmate lobes. The basal lobes are relatively small, while the upper lobes are larger and deeply notched. In contrast with the angular notching of the Silver Maple, however, the notches tend to be rounded at their interior. The fall color is often spectacular, ranging from bright yellow through orange to fluorescent red-orange. The flowers are in corymbs of 5-10 together, yellow-green and without petals; flowering occurs in early spring after 30-55 growing degree days. The fruit is a double samara with two winged seeds, the seeds are globose, 7-10 mm diameter, the wing 2-3 cm long. This tree is closely related to the Black Maple which is sometimes included in this species but sometimes separated as Acer nigrum. In some parts of Eastern North America (particularly more urbanized areas), the Sugar Maple is being displaced by the Norway Maple, which has similar leaves and habit, but can be differentiated by the white sap in the petiole; the Sugar Maple has clear sap. The Norway Maple is considerably more tolerant of urban conditions than the Sugar Maple, making it a natural replacement in those areas heavily disturbed by human activities.

Cultivation and uses

Sugar Maple, and also Black Maple, are superb sources of sap for making maple syrup, with the Black Maple being regarded as slightly better. Almost all maples can be used as a sap source for maple syrup, but none of the others are as good as these two. The wood is one of the hardest of the maples, and is prized for furniture and flooring. Bowling alleys and bowling pins are both commonly manufactured from sugar maple. A special type of maple, "birdseye maple" with wavy grain, is especially valued. birdseye maple The Sugar Maple is a favorite street and garden tree, because it is easy to propagate and transplant, is fairly fast-growing, and has beautiful fall color; however, its intolerance of pollution and inner city conditions make it a common victim of maple decline. It also has some of the most dense shade to be found in shade trees. The shade and the shallow, fibrous roots may interfere with grass growing under the trees. Cultivars of Sugar Maple include the tough-leaved 'Fall Fiesta', 'Green Mountain' and 'Legacy', pyramidal 'Arrowhead', fast-growing 'Bonfire' and cutleaf 'Sweet Shadow'. 'Unity' is a hardy selection suitable for the Prairie Provinces of Canada as far north as Edmonton, Alberta. Columnar varieties include 'Apollo', 'Columnare', 'Monumentale', 'Temple's Upright' and the very narrow 'Newton Sentry'. Sugar Maple is the State Tree of New York, Vermont, West Virginia and Wisconsin.

References

- [http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/acer/saccharum.htm Godman, Yawney and Tubbs. Sugar Maple]
- [http://www.hcs.ohio-state.edu/hcs/TMI/Plantlist/ac_harum.html Acer saccharum]
- [http://www.agnr.umd.edu/users/ipmnet/99-3nnws2.htm Columnar Trees for the Landscape] Maple, Sugar Maple, Sugar ja:サトウカエデ

Tree

, the tallest tree species on earth]] A tree can be defined as a large, perennial, woody plant. Though there is no set definition regarding minimum size, the term generally applies to plants at least 6 m (20 ft) high at maturity and, more importantly, having secondary branches supported on a single main stem or trunk (see shrub for comparison). Compared with most other plant forms, trees are long-lived. A few species of trees grow to 100 m tall, and some can live for several thousand years. Trees are important components of the natural landscape and significant elements in landscaping, and in agriculture supplying orchard crops (such as apples). Trees also play an important role in many of the world's mythologies (see Tree (mythology)).

Classifications

Tree (mythology)]] A tree is a plant form and trees occur in many different orders and families of plants. Trees thus show a wide variety of growth form, leaf type and shape, bark characteristics, reproductive structures, etc. The earliest trees were tree ferns and horsetails, which grew in vast forests in the Carboniferous Period; tree ferns still survive, but the only surviving horsetails are not of tree form. Later, in the Triassic Period, conifers, ginkgos, cycads and other gymnosperms appeared, and subsequently flowering plants in the Cretaceous Period. Most species of trees today are flowering plants and conifers. The listing below gives examples of many well-known trees and how they are typically classified. A small group of trees growing together is called a grove or copse, and a landscape covered by a dense growth of trees is called a forest. Several biotopes are defined largely by the trees that inhabit them; examples are rainforest and taiga (see ecozones). A landscape of trees scattered or spaced across grassland (usually grazed or burned over periodically) is called a savanna.

Morphology

The basic parts of a tree are the roots, trunk(s), branches, twigs and leaves. Tree stems consist mainly of support and transport tissues (xylem and phloem). Wood consists of xylem cells, and bark is made of phloem and other tissues external to the vascular cambium. Trees may be broadly grouped into exogenous and endogenous trees according to the way in which their stem diameter increases. Exogenous trees, which comprise the great majority of modern trees (all conifers, and all broadleaf trees), grow by the addition of new wood outwards, immediately under the bark. Endogenous trees, mainly in the monocotyledons (e.g. palms), grow by addition of new material inwards. As an exogenous tree grows, it creates growth rings. In temperate climates, these are commonly visible due to changes in the rate of growth with temperature variation over an annual cycle. These rings can be counted to determine the age of the tree, and used to date cores or even wood taken from trees in the past; this practice is known as the science of dendrochronology. In some tropical regions with constant year-round climate, growth is continuous and distinct rings are not formed, so age determination is impossible. Age determination is also impossible in endogenous trees. dendrochronology, Chile]] The roots of a tree are generally embedded in earth, providing anchorage for the above-ground biomass and absorbing water and nutrients from the soil. Above ground, the trunk gives height to the leaf-bearing branches, aiding in competition with other plant species for sunlight. In many trees, the arrangement of the branches optimizes exposure of the leaves to sunlight. Not all trees have all the plant organs or parts mentioned above. For example, most palm trees are not branched, the saguaro cactus of North America has no functional leaves, tree ferns do not produce bark, etc. Based on their general shape and size, all of these are nonetheless generally regarded as trees. Indeed, sometimes size is the more important consideration. A plant form that is similar to a tree, but generally having smaller, multiple trunks and/or branches that arise near the ground, is called a shrub. However, no sharp differentiation between shrubs and trees is possible. Given their small size, bonsai plants would not technically be 'trees', but one should not confuse reference to the form of a species with the size or shape of individual specimens. A spruce seedling does not fit the definition of a tree, but all spruces are trees. Bamboos by contrast, do show most of the characteristics of trees, yet are rarely called trees.

Champion trees

The world's champion trees can be considered on several factors; height, trunk diameter or girth, total size, and age. It is significant that in each case, the top position is always held by a conifer, though a different species in each case; in most measures, the second to fourth places are also held by conifers. ;Tallest trees The heights of the tallest trees in the world have been the subject of considerable dispute and much (often wild) exaggeration. Modern verified measurement with laser rangefinders combined with tape drop measurements made by tree climbers, carried out by the [http://www.uark.edu/misc/ents/home.htm U.S. Eastern Native Tree Society] has shown that most older measuring methods and measurements are unreliable, often producing exaggerations of 5% to 15% above the real height. Historical claims of trees of 114 m, 117 m, 130 m, and even 150 m, are now largely disregarded as unreliable, fantasy or outright fraud. The following are now accepted as the top five tallest reliably measured species: # Coast Redwood Sequoia sempervirens: 112.83 m, Humboldt Redwoods State Park, California ([http://www.conifers.org/cu/se/index.htm Gymnosperm Database]) # Coast Douglas-fir Pseudotsuga menziesii: 100.3 m, Brummit Creek, Coos County, Oregon ([http://www.conifers.org/pi/ps/menziesii2.htm Gymnosperm Database]) # Sitka Spruce Picea sitchensis: 96.7 m, Prairie Creek Redwoods State Park, California ([http://www.conifers.org/pi/pic/sitchensis.htm Gymnosperm Database]) # Giant Sequoia Sequoiadendron giganteum: 93.6 m, Redwood Mountain Grove, California ([http://www.conifers.org/cu/se2/index.htm Gymnosperm Database]) # Australian Mountain-ash Eucalyptus regnans: 92.0 m, Styx Valley, Tasmania ([http://www.forestrytas.com.au/forestrytas/tasfor/tasforests_12/tasfor_12_09.pdf Forestry Tasmania] [pdf file]) ;Stoutest trees The girth (circumference) of a tree is – or at least should be – much easier to measure than the height, as it is a simple matter of stretching a tape round the trunk, and pulling it taut to find the circumference. Despite this, U.K. tree author Alan Mitchell made the following comment about measurements of yew trees in the British Isles: :"The aberrations of past measurements of yews are beyond belief. For example, the tree at Tisbury has a well-defined, clean, if irregular bole at least 1.5 m long. It has been found to have a girth which has dilated and shrunk in the following way: 11.28 m (1834 Loudon), 9.3 m (1892 Lowe), 10.67 m (1903 Elwes and Henry), 9.0 m (1924 E. Swanton), 9.45 m (1959 Mitchell) .... Earlier measurements have therefore been omitted". As a general standard, tree girth is taken at 'breast height'; this is defined differently in different situations, with most foresters measuring girth at 1.3 m above ground, while ornamental tree measurers usually measure at 1.5 m above ground; in most cases this makes little difference to the measured girth. On sloping ground, the "above ground" reference point is usually taken as the highest point on the ground touching the trunk, but some use the average between the highest and lowest points of ground. Some of the inflated old measurements may have been taken at ground level. Some past exaggerated measurements also result from measuring the complete next-to-bark measurement, pushing the tape in and out over every crevice and buttress. Modern trends are to cite the tree's diameter rather than the circumference; this is obtained by dividing the measured circumference by π; it assumes the trunk is circular in cross-section (an oval or irregular cross-section would result in a mean diameter slightly greater than the assumed circle). This is cited as dbh (diameter at breast height) in tree literature. A further problem with measuring baobabs Adansonia is that these trees store large amounts of water in the very soft wood in their trunks. This leads to marked variation in their girth over the year, swelling to a maximum at the end of the rainy season, minimum at the end of the dry season. Although baobabs have some of the highest girth measurements of any trees, no accurate measurements are currently available, but probably do not exceed 10-11 m diameter. The stoutest species in diameter, excluding baobabs, are: # Montezuma Cypress Taxodium mucronatum: 11.42 m, Árbol del Tule, Santa Maria del Tule, Oaxaca, Mexico (A. F. Mitchell, International Dendrology Society Year Book 1983: 93, 1984). # Giant Sequoia Sequoiadendron giganteum: 8.85 m, General Grant tree, Grant Grove, California ([http://www.conifers.org/cu/se2/index.htm Gymnosperm Database]) # Coast Redwood Sequoia sempervirens: 7.44 m, Prairie Creek Redwoods State Park, California ([http://www.conifers.org/cu/se/index.htm Gymnosperm Database]) ;Largest trees The largest trees in total volume are those which are both tall and of large diameter, and in particular, which hold a large diameter high up the trunk. Measurement is very complex, particularly if branch volume is to be included as well as the trunk volume, so measurements have only been made for a small number of trees, and generally only for the trunk. No attempt has ever been made to include root volume. The top four species measured so far are ([http://www.conifers.org/topics/biggest.htm Gymnosperm Database]): # Giant Sequoia Sequoiadendron giganteum: 1489 m³, General Sherman tree # Coast Redwood Sequoia sempervirens: 1045 m³, Del Norte Titan tree # Western Redcedar Thuja plicata: 500 m³, Quinault Lake Redcedar # Kauri Agathis australis: 400 m³, Tane Mahuta tree (total volume, including branches, 516.7 m³)
However, the Alerce Fitzroya cupressoides, as yet un-measured, may well slot in at third or fourth place, and Montezuma Cypress Taxodium mucronatum is also likely to be high in the list. The largest angiosperm tree is a Australian Mountain-ash, the 'El Grande' tree of about 380 m³ in Tasmania. ;Oldest trees The oldest trees are determined by growth ring counts in cores taken from the edge to the centre of the tree or from entire cross-sections. Accurate determination is only possible for trees which produce growth rings, generally those which occur in seasonal climates; trees in uniform non-seasonal tropical climates grow continuously and do not have distinct growth rings. It is also only possible for trees which are solid to the centre of the tree; many very old trees become hollow as the dead heartwood decays away. For some of these species, age estimates have been made on the basis of extrapolating current growth rates, but the results are usually little better than guesswork or wild speculation. The verified oldest measured ages are ([http://www.conifers.org/topics/oldest.htm Gymnosperm Database]): # Great Basin Bristlecone Pine Pinus longaeva: 4844 years # Alerce Fitzroya cupressoides: 3622 years # Giant Sequoia Sequoia sempervirens: 3266 years # Huon-pine Lagarostrobos franklinii: 2500 years # Rocky Mountains Bristlecone Pine Pinus aristata: 2435 years Other species suspected of reaching exceptional age include European Yew Taxus baccata (probably over 3000 years) and Western Redcedar Thuja plicata. The oldest verified age for an angiosperm tree is 2293 years for the Sri Maha Bodhi Sacred Fig (Ficus religiosa) planted in 288 BC at Anuradhapura, Sri Lanka; this is also the oldest human-planted tree with a known planting date.

Major tree genera

Flowering plants (Magnoliophyta; angiosperms)

Dicotyledons (Magnoliopsida; broadleaf or hardwood trees)

- Anacardiaceae (Cashew family)
- Cashew, Anacardium occidentale
- Mango, Mangifera indica
- Pistachio, Pistacia vera
- Sumac, Rhus species
- Lacquer tree, Toxicodendron verniciflua
- Annonaceae (Custard apple family)
- Cherimoya Annona cherimola
- Custard apple Annona reticulata
- Pawpaw Asimina triloba
- Soursop Annona muricata
- Apocynaceae (Dogbane family)
- Pachypodium Pachypodium species
- Aquifoliaceae (Holly family)
- Holly, Ilex species
- Araliaceae (Ivy family)
- Kalopanax, Kalopanax pictus Kalopanax tree (background) in fall]]
- Betulaceae (Birch family)
- Alder, Alnus species
- Birch, Betula species
- Hornbeam, Carpinus species
- Hazel, Corylus species
- Bignoniaceae (family)
- Catalpa, Catalpa species
- Cactaceae (Cactus family)
- Saguaro, Carnegiea gigantea
- Cannabaceae (Cannabis family)
- Hackberry, Celtis species
- Cornaceae (Dogwood family)
- Dogwood, Cornus species
- Dipterocarpaceae family
- Garjan Dipterocarpus species
- Sal Shorea species
- Ericaceae (Heath family)
- Arbutus, Arbutus species
- Eucommiaceae (Eucommia family)
- Eucommia Eucommia ulmoides
- Fabaceae (Pea family)
- Acacia, Acacia species
- Honey locust, Gleditsia triacanthos
- Black locust, Robinia pseudoacacia
- Laburnum, Laburnum species
- Pau Brasil, Brazilwood, Caesalpinia echinata
- Fagaceae (Beech family )
- Chestnut, Castanea species
- Beech, Fagus species
- Southern beech, Nothofagus species
- Tanoak, Lithocarpus densiflorus
- Oak, Quercus species
- Fouquieriaceae (Boojum family)
- Boojum, Fouquieria columnaris
- Hamamelidaceae (Witch-hazel family)
- Sweetgum, Liquidambar species
- Persian Ironwood, Parrotia persica
- Juglandaceae (Walnut family)
- Walnut, Juglans species
- Hickory, Carya species
- Wingnut, Pterocarya species
- Lauraceae (Laurel family)
- Cinnamon Cinnamomum zeylanicum
- Bay Laurel Laurus nobilis
- Avocado Persea americana
- Lecythidaceae (Paradise nut family)
- Brazil Nut Bertholletia excelsa
- Lythraceae Loosestrife family
- Crape-myrtle Lagerstroemia species
- Magnoliaceae (Magnolia family)
- Tulip tree, Liriodendron species
- Magnolia, Magnolia species
- Malvaceae (Mallow family; including Tiliaceae and Bombacaceae) Bombacaceae
- Baobab, Adansonia species
- Silk-cotton tree, Bombax species
- Bottletrees, Brachychiton species
- Kapok, Ceiba pentandra
- Durian, Durio zibethinus
- Balsa, Ochroma lagopus
- Cacao (cocoa), Theobroma cacao
- Linden (Basswood, Lime), Tilia species
- Meliaceae (Mahogany family)
- Neem, Azadirachta indica
- Bead tree, Melia azedarach
- Mahogany, Swietenia mahagoni
- Moraceae (Mulberry family)
- Fig, Ficus species
- Mulberry, Morus species
- Myristicaceae (Nutmeg family)
- Nutmeg, Mysristica fragrans
- Myrtaceae (Myrtle family)
- Eucalyptus, Eucalyptus species
- Myrtle, Myrtus species
- Guava, Psidium guajavaGuava in flower]]
- Nyssaceae (Tupelo family; sometimes included in Cornaceae)
- Tupelo, Nyssa species
- Dove tree, Davidia involucrata
- Oleaceae (Olive family)
- Olive, Olea europaea
- Ash, Fraxinus species
- Paulowniaceae (Paulownia family)
- Foxglove Tree, Paulownia species
- Platanaceae (Plane family)
- Plane, Platanus species
- Rhizophoraceae (Mangrove family)
- Red Mangrove, Rhizophora mangle
- Rosaceae (Rose family)
- Rowans, Whitebeams, Service Trees Sorbus species
- Hawthorn, Crataegus species
- Pear, Pyrus species
- Apple, Malus species
- Almond, Prunus dulcis
- Peach, Prunus persica
- Plum, Prunus domestica
- Cherry, Prunus species
- Rubiaceae (Bedstraw family)
- Coffee, Coffea species
- Rutaceae (Rue family)
- Citrus, Citrus species
- Cork-tree, Phellodendron species
- Euodia, Tetradium species
- Salicaceae (Willow family)
- Aspen, Populus species
- Poplar, Populus species
- Willow, Salix species Willow
- Sapindaceae (including Aceraceae, Hippocastanaceae) (Soapberry family)
- Maple, Acer species
- Buckeye, Horse-chestnut, Aesculus species
- Mexican Buckeye, Ungnadia speciosa
- Lychee, Litchi sinensis
- Golden rain tree, Koelreuteria paniculata
- Sapotaceae (Sapodilla family)
- Gutta-percha, Palaquium species
- Tambalacoque, or "dodo tree", Sideroxylon grandiflorum, previously Calvaria major
- Simaroubaceae family
- Tree of heaven, Ailanthus species
- Theaceae (Camellia family)
- Gordonia, Gordonia species
- Stuartia, Stuartia species
- Thymelaeaceae (Thymelaea family)
- Ramin, Gonystylus species
- Ulmaceae (Elm family)
- Elm, Ulmus species
- Zelkova, Zelkova species
- Verbenaceae family
- Teak, Tectona species

Monocotyledons (Liliopsida)

Monocotyledon
- Agavaceae (Agave family)
- Cabbage tree, Cordyline australis
- Dragon tree, Dracaena draco
- Joshua tree, Yucca brevifolia
- Arecaceae (Palmae) (Palm family)
- Areca Nut, Areca catechu
- Coconut Cocos nucifera
- Date Palm, Phoenix dactylifera
- Chusan Palm, Trachycarpus fortunei
- Poaceae (grass family)
- Bamboos Poaceae subfamily Bambusoideae
- Note that banana 'trees' are not actually trees; they are not woody nor is the stalk perennial.

Conifers (Pinophyta; softwood trees)

- Araucariaceae (Araucaria family)
- Araucaria, Araucaria species
- Kauri, Agathis species
- Cupressaceae (Cypress family)
- Cypress, Cupressus species
- Cypress, Chamaecyparis species
- Juniper, Juniperus species
- Alerce or Patagonian cypress, Fitzroya cupressoides
- Sugi, Cryptomeria japonica
- Coast Redwood, Sequoia sempervirens
- Giant Sequoia, Sequoiadendron giganteum
- Dawn Redwood, Metasequoia glyptostroboides
- Bald Cypress, Taxodium distichum
- Pinaceae (Pine family)
- White pine, Pinus species
- Pinyon pine, Pinus species
- Pine, Pinus species
- Spruce, Picea species
- Larch, Larix species
- Douglas-fir, Pseudotsuga species
- Fir, Abies species
- Cedar, Cedrus species
- Podocarpaceae (Yellowwood family)
- African Yellowwood, Afrocarpus falcatus
- Totara, Podocarpus totara
- Sciadopityaceae
- Kusamaki, Sciadopitys species
- Taxaceae (Yew family)
- Yew, Taxus species

Ginkgos (Ginkgophyta)

- Ginkgoaceae (Ginkgo family)
- Ginkgo, Ginkgo biloba

Cycads (Cycadophyta)

- Cycadaceae family
- Ngathu cycad, Cycas angulata
- Zamiaceae family
- Wunu cycad, Lepidozamia hopei

Ferns (Pterophyta)

- Cyatheaceae and Dicksoniaceae families
- Tree ferns, Cyathea, Alsophila, Dicksonia (not a monophyletic group)

Life stages

The life cycles of trees, especially conifers, are divided into the following stages in forestry for survey and documentation purposes: # Seed # Seedling: the above ground part of the embryo that sprout from the seed # Sapling: After the seedling reaches 1m tall, and until it reaches 7cm in stem diameter # Pole: young trees from 7-30cm diameter # Mature tree: over 30cm diameter, reproductive years begin # Old tree: dominate old growth forest; height growth slows greatly, with majority of productivity in seed production # Overmature: dieback and decay become common # Snag: standing dead wood # Log/debris: fallen dead wood Tree diameters are measured at height of between 1.3-1.5m above the highest point on the ground at its base. The 7cm diameter definition is economically based, from the smallest saleable stem size (for paper production, etc), and the 30cm diameter is the smallest base diameter for sawlogs. Each stage may be uniquely perceptive to different pathogens and suitable for especially adapted arboreal animals.

External links

- [http://www.globaltrees.org/default.asp GLOBAL TREES .org] Campaigning to save the world's most threatened trees
- [http://www.fssca.net/romero/ Romero Memorial Tree Project] Plant a tree in El Salvador

Bibliography

- Pakenham, T. (2002). Remarkable Trees of the World. ISBN 0297843001
- Pakenham, T. (1996). Meetings with Remarkable Trees. ISBN 0297832557 Category:Plants
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- Category:Botany Category: plant morphology ms:Pokok ja:木 simple:Tree th:ต้นไม้

North America

North America is a continent in the northern hemisphere bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the North Pacific Ocean. It covers an area of 24,497,994 km² (9,458,728 sq mi), or about 4.8% of the Earth's surface. As of July 2002, its population was estimated at more than 514,600,000. It is the third largest continent in area, after Asia and Africa, and is fourth in population after Asia, Africa, and Europe. Both North and South America are named after Amerigo Vespucci, who was the first European to suggest that the Americas were not the East Indies, but a previously undiscovered (by Europeans) New World. North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America. North America's only land connection is to South America at the narrow Isthmus of Panama. (For geopolitical reasons, all of Panama – including the segment east of the Panama Canal in the isthmus – is often considered a part of North America alone.) According to some authorities, North America begins not at the Isthmus of Panama but at the Isthmus of Tehuantepec, with the intervening region called Central America and resting on the Caribbean Plate. Most, however, tend to see Central America as a region of North America, considering it too small to be a continent on its own. Greenland, although a part of North America geographically, is not considered to be part of the continent politically.

Physical features

Greenland, plutonic, metamorphic rock types of North America. ]] Plate tectonics recognizes the vast majority of North America as being the surface of the North American Plate. Parts of California and western Mexico are known for being the edge of the Pacific Plate, with the two plates meeting along the San Andreas fault. The continent can be divided into four great regions (each of which contains many sub-regions): the Great Plains stretching from the Gulf of Mexico to the Canadian Arctic; the geologically young, mountainous west, including the Rocky Mountains, the Great Basin, California and Alaska; the raised but relatively flat plateau of the Canadian Shield in the northeast; and the varied eastern region, which includes the Appalachian Mountains, the coastal plain along the Atlantic seaboard, and the Florida peninsula. Mexico, with its long plateaus and cordilleras, falls largely in the western region, although the eastern coastal plain does extend south along the Gulf. The western mountains are split in the middle, into the main range of the Rockies and the coast ranges in California, Oregon, Washington, and British Columbia with the Great Basin – a lower area containing smaller ranges and low-lying deserts – in between. The highest peak is Denali in Alaska. Since 1931, Rugby, North Dakota, has officially been recognized as being at the geographic center of North America. The location is marked by a 4.5 metre (15 foot) field stone obelisk. Image:North america terrain 2003 map.jpg|North America bedrock and terrain. Image:North america basement rocks.png|North American cratons and basement rocks. Image:North America Tectonic Elements.jpg|Tectonic elements of North America Image:North america craton nps.gif|North American craton.

Territories and regions

craton On the main continent landmass, there are three large and relatively populous countries:
- Canada - many large islands off the shore of North America belong to Canada, including Vancouver Island and the Queen Charlotte Islands on the west, Prince Edward Island, Newfoundland and Cape Breton Island on the east, and the Canadian Arctic islands (including Ellesmere Island, Baffin Island, and Victoria Island) in the north
- Mexico - the Revillagigedo archipelago and numerous smaller islands off its coast belong to Mexico
- The United States - the 48 contiguous states and Alaska are part of North America, while the state of Hawaii in the Pacific Ocean is not; the Aleutian Islands south of Alaska also belong to the U.S. At the southern end of the continent, in a relatively small area known as Central America, are the countries of:
- Belize
- Costa Rica
- El Salvador
- Guatemala
- Honduras
- Nicaragua
- Panama ¹ At the southeastern end of the continent lies a chain of islands territories called the Antilles, the Caribbean or the West Indies, which include the countries:
- Antigua and Barbuda
- Bahamas
- Barbados
- Cuba
- Dominica
- Dominican Republic
- Grenada
- Haiti
- Jamaica
- Saint Kitts and Nevis
- Saint Lucia
- Saint Vincent and the Grenadines
- Trinidad and Tobago ¹ And the dependencies:
- Anguilla (British overseas territory)
- Aruba ² (part of the Kingdom of the Netherlands)
- Cayman Islands (British overseas territory)
- Guadeloupe (French région d'outre-mer)
- Martinique (French région d'outre-mer)
- Montserrat (British overseas territory)
- Navassa Island (U.S. territory)
- Netherlands Antilles ¹ (part of the Kingdom of the Netherlands)
- Puerto Rico (U.S. commonwealth)
- Turks and Caicos Islands (British overseas territory)
- British Virgin Islands (British overseas territory)
- U.S. Virgin Islands (territory of the USA) Lying in the Atlantic Ocean but considered part of the continent are the dependencies:
- Bermuda, a British overseas territory found about 1,072 km (670 mi.) southeast of New York City
- Greenland, the largest island in the world and a self-governing dependency of Denmark, which is located in the far north of the continent to the east of Nunavut.
- Saint Pierre and Miquelon, a French collectivité d'outre-mer off the south coast of Newfoundland, is the last of France's once vast possessions in America north of the Caribbean. ¹ These states and dependencies have territory both in North and South America.
² These dependencies lie in South America, but are considered North American because of cultural and historical reasons.
See here for details.

Usage

The United States, Canada, and the other English-speaking nations of the Americas (Belize, Guyana, and the Anglophone Caribbean) are sometimes grouped under the term Anglo-America, while the remaining nations of North and South America are grouped under the term Latin America. Alternatively, Northern America is used to refer to Canada and the U.S. together (plus Greenland and Bermuda), while Central America is mainland North America south of the United States. The West Indies generally include all islands in the Caribbean Sea. In this respect, Latin America generally includes Central America and South America and, sometimes, the West Indies. The term Middle America is sometimes used to refer to Mexico, Central America, and the Caribbean collectively. The term "North America" may mean different things to different people. The term in common usage is often taken to mean "the United States and Canada, only" by some people of the United States and Canada, excluding Mexico and the countries of Central America, unless the context makes it clear that they are to be included (such as with specific reference to Mexico, when talking about NAFTA). For example, guides to wild flora and fauna published by the National Audubon Society for "North America" frequently include only species found in Canada and the U.S. This may be attributed to the fact that culturally and economically, the U.S. and Canada are more alike to each other than they are to the rest of North America. Mexicans, however, are acutely aware that Mexico is a part of North America and object to this usage. Central Americans, however, are generally content to be called Central Americans – largely because of their shared history, which includes several attempts at supranational integration in the region and in which Mexico, their much larger northern neighbor, was never involved.

Political divisions and regions

Notes:
¹ Continental regions as per UN categorisations/map.
² Depending on definitions, Aruba, Netherlands Antilles, Panama, and Trinidad and Tobago have territory in one or both of North and South America.
³ Due to ongoing activity of the Soufriere Hills volcano beginning 1995, much of Plymouth, Montserrat's de jure capital, was destroyed and government offices relocated to Brades.

External links

- http://www.america-norte.com/america-norte-mapa.htm Category:Continents Category:North America zh-min-nan:Pak Bí-chiu ko:북아메리카 ja:北アメリカ simple:North America th:ทวีปอเมริกาเหนือ

Leaf

:This article is about the leaf, a plant organ. See Leaf (disambiguation) for other meanings. ---- In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the chloroplast containing cells (chlorenchyma tissue) to light over a broad area, and to allow light to penetrate fully into the tissues. Leaves are also the sites in most plants where respiration, transpiration, and guttation take place. Leaves can store food and water, and are modified in some plants for other purposes. The comparable structures of ferns are correctly referred to as fronds. frond frond frond

Leaf anatomy

A structurally complete leaf of an angiosperm consists of a petiole (leaf stem), a lamina (leaf blade), and stipules (small processes located to either side of the base of the petiole). The point at which the petiole attaches to the stem is called the leaf axil. Not every species produces leaves with all of these structural parts. In some species, paired stipules are not obvious or are absent altogether; a petiole may be absent; or the blade may not be laminar (flattened). The tremendous variety shown in leaf structure (anatomy) from species to species is presented in detail below under Leaf types, arrangements, and forms. A leaf is considered to be a plant organ, typically consisting of the following tissues: # An epidermis that covers the upper and lower surfaces # An interior chlorenchyma called the mesophyll # An arrangement of veins (the vascular tissue). stipule

Epidermis

The epidermis is the outer multi-layered group of cells covering the leaf. It forms the boundary between the plant and the external world. The epidermis serves several functions: protection against water loss, regulation of gas exchange, secretion of metabolic compounds, and (in some species) absorption of water. Most leaves show dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. The epidermis is usually transparent (epidermal cells lack chloroplasts) and coated on the outer side with a waxy cuticle that prevents water loss. The cuticle may be thinner on the lower epidermis than on the upper epidermis; and is thicker on leaves from dry climates as compared with those from wet climates. The epidermis tissue includes several differentiated cell types: epidermal cells, guard cells, subsidiary cells, and epidermal hairs (trichomes). The epidermal cells are the most numerous, largest, and least specialized. These are typically more elongated in the leaves of monocots than in those of dicots. The epidermis is covered with pores called stomata (sing., stoma), part of a stoma complex consisting of a pore surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts. The stoma complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Typically, the stomata are more numerous over the abaxial (lower) epidermis than the (adaxial) upper epidermis. Trichomes or hairs grow out from the epidermis in many species.

Mesophyll

Most of the interior of the leaf between the upper and lower layers of epidermis is a parenchyma (ground tissue) or chlorenchyma tissue called the mesophyll (= middle leaf). This "assimilation tissue" is the primary location of photosynthesis in the plant. The products of photosynthesis are called assimilates. In ferns and most flowering plants the mesophyll is divided into two layers:
- An upper palisade layer of tightly packed, vertically elongated cells, one to two cells thick, directly beneath the adaxial epidermis. Its cells contain many more chloroplasts than the spongy layer. These long cylindrical cells are regularly arranged in one to five rows. Cylindrical cells, with the chloroplasts close to the walls of the cell, can take optimal advantage of light. The slight separation of the cells provides maximum absorption of carbon dioxide. This separation must be minimal to afford capillary action for water distribution. In order to adapt to their different environment (such as sun or shade), plants had to adapt this structure to obtain optimal result. Sun leaves have a multi-layered palisade layer, while shade leaves or older leaves closer to the soil, are single-layered.
- Beneath the palisade layer is the spongy layer. The cells of the spongy layer are more rounded and not so tightly packed. There are large intercellular air spaces. These cells contain less chloroplasts than those of the palisade layer. The pores or stomata of the epidermis open into substomatal chambers, connecting to air spaces between the spongy layer cells. These two different layers of the mesophyll are absent in many aquatic and marsh plants. Even an epidermis and a mesophyll may be lacking. Instead for their gaseous exchanges they use a homogenous aerenchyma (thin-walled cells separated by large gas-filled spaces). Their stomata are situated at the upper surface. Leaves are normally green in color, which comes from chlorophyll found in plastids in the chlorenchyma cells. Plants that lack chlorophyll cannot photosynthesize. Leaves in temperate, boreal, and seasonally dry zones may be seasonally deciduous (falling off or dying for the inclement season). This mechanism to shed leaves is called abscission. After the leaf is shed, a leaf scar develops on the twig. In cold autumns they sometimes turn yellow, bright orange or red as various accessory pigments (carotenoids and anthocyanins) are revealed when the tree responds to cold and reduced sunlight by curtailing chlorophyll production.

Veins

The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. They are typical examples of pattern formation through ramification. The veins are made up of:
- xylem, which brings water from the stem into the leaf.
- phloem, which usually moves sap out, the latter containing the glucose produced by photosynthesis in the leaf. The xylem typically lies over the phloem. Both are embedded in a dense parenchyma tissue (= ground tissue), called pith, with usually some structural collenchyma tissue present.

Leaf morphology

External leaf characteristics (such as shape, margin, hairs, etc.) are important for identifying plant species, and botanists have developed a rich terminology for describing leaf characteristics. phloem Leaves may be classified in many different ways, and the type is usually characteristic of a species, although some species produce more than one type of leaf. The terminology associated with describing leaf morphology is presented (with illustrations) at [http://wikibooks.org/wiki/Botany:_Leaves_(forms) Wikibooks].

Basic leaf types

- Ferns have fronds.
- Conifer leaves are typically needle-, awl-, or scale-shaped
- Angiosperm (flowering plant) leaves: the standard form includes stipules, petiole, and lamina.
- Microphyll leaves.
- Sheath leaves (type found in most grasses).
- Other specialized leaves.

Arrangement on the stem

As a stem grows, leaves tend to appear arranged around the stem in away that optimizes yield of light. In essence, leaves come off the stem in a spiral pattern, either clockwise or counterclockwise, with (depending upon the species) the same angle of divergence. There is a regularity in these angles and they follow the numbers in a Fibonacci series: 1/2, 2/3, 3/5, 5/8, 8/13, 13/21, 21/34, 34/55, 55/89. This series tends to a limit of 360° x 34/89 = 137,52 or 137° 30', an angle known mathematically as the 'golden angle'. In the series, the numerator gives the number of complete turns or gyres until the leaf arrives at the initial position. The denominator gives the number of leaves in the arrangement. This can be demonstrated by the following:
- alternate leaves have an angle of 180° (or 1/2)
- 120° (or 1/3) : three leaves in one circle
- 144° (or 2/5) : five leaves in two gyres
- 135° (or 3/8) : eight leaves in three gyres. The fact that an arrangement of anything in nature can be described by a mathematical formula is not in itself mysterious. Mathematics is the science of discovering numerical relationships and applying formulae to these relationships. The formulae themselves can provide clues to the underlying physiological processes that, in this case, determine where the next leaf bud will form in the elongating stem. However, we can more easily describe the arrangement of leaves using the following terms:
- Alternate — leaf attachments singular at nodes, and leaves alternate direction, to a greater or lesser degree, along the stem.
- Opposite — leaf attachments paired at each node; decussate if, as typical, each successive pair is rotated 90° going along the stem; or distichous if not rotated, but two-ranked (in the same plane).
- Whorled — three or more leaves attach at each point or node on the stem. As with opposite leaves, successive whorls may or may not be decussate, rotated by half the angle between the leaves in the whorl (i.e., successive whorls of three rotated 60°, whorls of four rotated 45°, etc). Note: opposite leaves may appear whorled near the tip of the stem.
- Rosulate — leaves form a rosette ( = a cluster of leaves growing in crowded circles from a common center). Fibonacci series

Divisions of the lamina (blade)

Two basic forms of leaves can be described considering the way the blade is divided. A simple leaf has an undivided blade. However, the leaf shape may be one of lobes, but the gaps between lobes do not reach to the main vein. A compound leaf has a fully subdivided blade, each leaflet of the blade separated along a main or secondary vein. Because each leaflet can appear to be a "simple leaf", it is important to recognize where the petiole occurs to identify a compound leaf. Compound leaves are a characteristic of some families of higher plants, such as the Fabaceae.
- Palmately compound leaves have the leaflets radiating from the end of the petiole, like fingers off the palm of a hand. There is no rachis, e.g. Cannabis (hemp) and Aesculus (buckeyes).
- Pinnately compound leaves have the leaflets arranged along the main or mid-vein (called a rachis in this case).
- odd pinnate: with a terminal leaflet, e.g. Fraxinus (ash).
- even pinnate: lacking a terminal leaflet, e.g. Swietenia (mahogany).
- Bipinnately compound leaves are twice divided: the leaflets are arranged along a secondary vein that is one of several branching off the rachis. Each leaflet is called a pinnule. The pinnules on one secondary vein are called pinna; e.g. Albizia (silk tree).
- trifoliate: a pinnate leaf with just three leaflets, e.g. Trifolium (clover), Laburnum (laburnum).
- pinnatifid: pinnately dissected to the midrib, but with the leaflets not entirely separate, e.g. some Sorbus (whitebeams). ;Characteristics of the petiole:
- Petiolated leaves have a petiole.
- In peltate leaves, the petiole attaches to the blade inside from the blade margin.
- Sessile or clasping leaves do not have a petiole. In sessile leaves the blade attaches directly to the stem. In clasping leaves, the blade partially or wholly surrounds the stem, giving the impression that the shoot grows through the leaf such as in Claytonia perfoliata of the purslane family (Portulacaceae). In some Acacia species, such as the Koa Tree (Acacia koa), the petioles are expanded or broadened and function like leaf blades; these are called phyllodes. There may or may not be normal pinnate leaves at the tip of the phyllode. ;Characteristics of the stipule
- A stipule, present on the leaves of many dicotyledons, is an appendage on each side at the base of the petiole, resembling a small leaf. They may be lasting and not be shed (a stipulate leaf, such as in roses and beans); or be shed as the leaf expands, leaving a stipule scar on the twig (an exstipulate leaf).
- The situation, arrangement, and structure of the stipules is called the stipulation.
- free
- adnate : fused to the petiole base
- ochreate : provided with ochrea, or sheath-formed stipules, e.g. rhubarb,
- encircling the petiole base
- interpetiolar : between the petioles of two opposite leaves.
- intrapetiolar : between the petiole and the subtending stem

Venation (arrangement of the veins)

rhubarb There are two subtypes of venation, craspedodromus (the major veins stretch up to the margin of the leaf) and camptodromous (major veins come close to the margin, but bend before they get to it).
- Feather-veined, reticulate — the veins arise pinnately from a single mid-vein and subdivide into veinlets. These, in turn, form a complicated network. This type of venation is typical for dicotyledons.
- Pinnate-netted, penniribbed, penninerved, penniveined; the leaf has usually one main vein (called the mid-vein), with veinlets, smaller veins branching off laterally, usually somewhat parallel to each other; eg Malus (apples).
- Three main veins originate from the base of the lamina, as in Ceanothus.
- Palmate-netted, palmate-veined, fan-veined; several main veins diverge from near the leaf base where the petiole attaches, and radiate toward the edge of the leaf; e.g. most Acer (maples).
- Parallel-veined, parallel-ribbed, parallel-nerved, penniparallel — veins run parallel most the length of the leaf, from the base to the apex. Commissural veins (small veins) connect the major parallel veins. Typical for most monocotyledons, such as grasses.
- Dichotomous — There are no dominant bundles, with the veins forking regularly by pairs; found in Ginkgo and some pteridophytes.
pteridophyte

Leaf terminology

;Shape See Leaf shape

Margins (edge)

The leaf margin is characteristic for a genus and aids in determining the species.
- entire: even; with a smooth margin; without toothing
- ciliate: fringed with hairs
- crenate: wavy-toothed; dentate with rounded teeth, such as Fagus (beech)
- dentate: toothed, such as Castanea (chestnut)
- coarse-toothed: with large teeth
- glandular toothed: with teeth that bear glands.
- denticulate: finely toothed
- doubly toothed: each tooth bearing smaller teeth, such as Ulmus (elm)
- lobate: indented, with the indentations not reaching to the center, such as many Quercus (oaks)
- palmately lobed: indented with the indentations reaching to the center, such as Humulus (hop).
- serrate: saw-toothed with asymmetrical teeth pointing forward, such as Urtica (nettle)
- serrulate: finely serrate
- sinuate: with deep, wave-like indentations; coarsely crenate, such as many Rumex (docks)
- spiny: with stiff, sharp points, such as some Ilex (hollies) and Cirsium (thistles).

Tip of the leaf

- acuminate: long-pointed, prolonged into a narrow, tapering point in a concave manner.
- acute: ending in a sharp, but not prolonged point
- cuspidate: with a sharp, elongated, rigid tip; tipped with a cusp.
- emarginate: indented, with a shallow notch at the tip.
- mucronate: abruptly tipped with a small short point, as a continuation of the midrib; tipped with a mucro.
- mucronulate: mucronate, but with a smaller spine.
- obcordate: inversely heart-shaped, deeply notched at the top.
- obtuse: rounded or blunt
- truncate: ending abruptly with a flat end, that looks cut off.

Base of the leaf

- acuminate: coming to a sharp, narrow, prolonged point.
- acute: coming to a sharp, but not prolonged point.
- auriculate: ear-shaped
- cordate: heart-shaped with the norch away from the stem.
- cuneate: wedge-shaped.
- hastate: shaped like an halberd and with the basal lobes pointing outward.
- oblique: slanting.
- reniform: kidney-shaped but rounder and broader than long.
- rounded: curving shape.
- sagittate: shaped like an arrowhead and with the acute basal lobes pointing downward.
- truncate: ending abruptly with a flat end, that looks cut off.

Surface of the leaf

The surface of a leaf can be described by several botanical terms:
- farinose: bearing farina; mealy, covered with a waxy, whitish powder.
- glabrous: smooth, not hairy.
- glaucous: with a whitish bloom; covered with a very fine, bluish-white powder.
- glutinous: sticky, viscid.
- papillate, papillose: bearing papillae (minute, nipple-shaped protuberances).
- pubescent: covered with erect hairs (especially soft and short ones)
- punctate: marked with dots; dotted with depressions or with translucent glands or colored dots.
- rugose: deeply wrinkled; with veins clearly visible.
- scurfy: covered with tiny, broad scalelike particles.
- tuberculate: covered with tubercles; covered with warty prominences.
- verrucose: warted, with warty outgrowths.
- viscid, viscous: covered with thick, sticky secretions.

Hairiness (trichomes)

Leaves can show several degrees of hairiness. The meaning of several of the following terms can overlap. See also : Trichome.
- glabrous: no hairs of any kind present.
- arachnoid, arachnose: with many fine, entangled hairs giving a cobwebby appearance.
- barbellate: with finely barbed hairs (barbellae).
- bearded: with long, stiff hairs.
- bristly: with stiff hair-like prickles.
- canescent: hoary with dense grayish-white pubescence.
- ciliate: marginally fringed with short hairs (cilia).
- ciliolate: minutely ciliate.
- floccose: with flocks of soft, woolly hairs, which tend to rub off.
- glandular: with a gland at the tip of the hair.
- hirsute: with rather rough or stiff hairs.
- hispid: with rigid, bristly hairs.
- hispidulous: minutely hispid.
- hoary: with a fine, close grayish-white pubescence.
- lanate, lanose: with woolly hairs.
- pilose: with soft, clearly separated hairs.
- puberulent, puberulous: with fine, minute hairs.
- pubescent: with soft, short and erect hairs.
- scabrous, scabrid: rough to the touch
- sericeous: silky appearance through fine, straight and appressed (lying close and flat) hairs.
- silky: with adpressed, soft and straight pubescence.
- stellate, stelliform: with star-shaped hairs.
- strigose: with appressed, sharp, straight and stiff hairs.
- tomentose: densely pubescent with matted, soft white woolly hairs.
- cano-tomentose: between canescent and tomentose
- felted-tomentose: woolly and matted with curly hairs.
- villous: with long and soft hairs, usually curved.
- woolly: with long, soft and tortuous or matted hairs.

Adaptations

In order to survive in a harsh environment, leaves can adapt in the following ways:
- Hairs develop on the leaf surface to trap humidity in dry climates, creating a large boundary layer to lessen water loss
- Leaves rustle to move humidity away from the surface reducing the boundary layer resistance between the leaf and the air.
- Plant prickles are modified clusters of epidermal hairs
- Waxy leaf surfaces form to prevent water loss
- Small, shiny leaves to deflect the sun's rays
- Thicker leaves to store water (e.g. rhubarb)
- Change to spines instead of laminar (blade) leaves (e.g. cactus)
- Shrink (to phyllodes) or disappear (with the appearance of cladodes), as photosynthetic functions are transferred to the leaf stem (Acacia species)
- Change shape to deflect wind or reduce wind resistance
- Leaves to trap insects (e.g. pitcher plant)
- Change to bulb parts to store food (e.g. onion)
- Produce aromatic oils to deter herbivores (e.g. eucalypts)
- Protect as spines, which are modified leaves.

External links

- [http://www.ibiblio.org/botnet/glossary/b_i.html Position and Arrangement] Category:Photosynthesis Category:Plant physiology Category:plant morphology Category:Plant anatomy ko:잎 ja:葉 th:ใบไม้

Silver Maple

The Silver Maple (Acer saccharinum) is a species of maple native to the eastern United States and adjacent parts of southeast Canada. It is a relatively fast-growing tree, commonly reaching a height of 20-30 m, exceptionally 35 m. It is often found along waterways and in wetlands, leading to the colloquial name "Water Maple". It is one of the most common trees in the United States. The leaves are palmate, 8-16 cm long and 6-12 cm broad, with deep angular notches between the five lobes. The 5-12 cm long, slender stalks of the leaves mean that even a light breeze can produce a striking effect as the silver undersides of the leaves are exposed. The flowers are in small panicles, produced before the leaves in early spring, with the seeds maturing in early summer. The seeds are winged, in pairs, small (5-10 mm diameter), the wing about 3-5 cm long. On mature trunks, the bark is gray and shaggy. On branches and young trunks, the bark is smooth and silvery gray. The Silver Maple has brittle wood, and is commonly damaged in storms. The roots are shallow and fibrous and easily invade septic fields and old drain pipes. It is, nonetheless, widely used as an ornamental tree because of its rapid growth and ease of propagation and transplanting. It is also commonly cultivated outside its native range, showing tolerance of a wide range of climates, growing successfully as far north as central Norway and south to Orlando, Florida. It can thrive in a Mediterranean climate, as at Jerusalem and Los Angeles, if summer water is provided. It is also grown in temperate parts of the Southern Hemisphere, as in Argentina and Uruguay. Silver Maple is closely related to Red Maple, and can hybridise with it, the hybrid being known as the Freeman Maple (Acer x freemanii). The Freeman Maple is a popular ornamental tree in parks and large gardens, combining the fast growth of Silver Maple with the less brittle wood and less invasive roots of Red Maple.

External link

[http://www.hort.uconn.edu/plants/a/acesac/acesac1.html UConn Plant Database: Silver Maple] Maple, Silver

Flower

:This article is about the plants; for other uses see Flower (disambiguation). Flower (disambiguation) Flower (Latin flos, floris; French fleur), a term popularly used for the bloom or blossom of a plant, is the reproductive structure of those plants classified as angiosperms (flowering plants; Division Magnoliophyta). The flower structure incorporates the reproductive organs, and its function is to produce seeds through sexual reproduction. For the higher plants, seeds are the next generation, and serve as the primary means by which individuals of a species are dispersed across the landscape. After fertilization, portions of the flower develop into a fruit containing the seed(s).

Flower anatomy

Flowering plants are heterosporangiate (producing two types of reproductive spores) and the pollen (male spores) and ovules (female spores) are produced in different organs, but these are together in a bisporangiate strobilus that is the typical flower. A flower is regarded as a modified stem (Eames, 1961) with shortened internodes and bearing, at its nodes, structures that may be highly modified leaves. In essence, a flower structure forms on a modified shoot or axis with an apical meristem that does not grow continuously (growth is determinate). The stem is called a pedicel, the end of which is the torus or receptacle. The parts of a flower are arranged in whorls on the torus. The four main parts or whorls (starting from the base of the flower or lowest node and working upwards) are as follows: flower
- calyx – the outer whorl of sepals; typically these are green, but are petal-like in some species.
- corolla – the whorl of petals, which are usually thin, soft and colored to attract insects that help the process of pollination.
- androecium (from Greek andros oikia: man's house) – one or two whorls of stamens, each a filament topped by an anther where pollen is produced. Pollen contains the male gametes.
- gynoecium (from Greek gynaikos oikia: woman's house) – one or more pistils. The female reproductive organ is the carpel: this contains an ovary with ovules (female gametes). A pistil may consist of a number of carpels merged together, in which case there is only one pistil to each flower, or of a single individual carpel (the flower is then called apocarpous). The sticky tip of the pistil, the stigma, is the receptor of pollen. The supportive stalk, the style becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma, to the ovules, carrying the reproductive material. carpel Although the floral structure described above is considered the "typical" structural plan, plant species show a wide variety of modifications from this plan. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species. For example, the two subclasses of flowering plants may be distinguished by the number of floral organs in each whorl: dicotyledons typically having 4 or 5 organs (or a multiple of 4 or 5) in each whorl and monocotyledons having three or some multiple of three. The number of carpels in a compound pistil may be only two, or otherwise not related to the above generalization for monocots and dicots. In the majority of species, individual flowers have both pistils and stamens as described above. These flowers are described by botanists as being perfect, bisexual, or hermaphrodite. However, in some species of plants the flowers are imperfect or unisexual: having only either male (stamens) or female (pistil) parts. In the latter case, if an individual plant is either male or female the species is regarded as dioecious. However, where unisexual male and female flowers appear on the same plant, the species is considered monoecious. Some flowers with both stamens and a pistil are capable of self-fertilization, which does increase the chance of producing seeds but limits genetic variation. The extreme case of self-fertilization occurs in flowers that always self-fertilize, such as the common dandelion. Conversely, many species of plants have ways of preventing self-fertilization. Unisexual male and female flowers on the same plant may not appear at the same time, or pollen from the same plant may be incapable of fertilizing its ovules. The latter flower types, which have chemical barriers to their own pollen, are referred to as self-sterile or self-incompatible. (See also: Plant sexuality) Plant sexuality Additional discussions on floral modifications from the basic plan are presented in the articles on each of the basic parts of the flower. In those species that have more than one flower on an axis, the collection of flowers is termed an inflorescence. In this sense, care must be exercised in considering what is a flower. In botanical terminology, a single daisy or sunflower for example, is not a flower but a flower head—an inflorescence comprised of numerous small flowers (sometimes called florets). Each small flower may be anatomically as described above.

Floral formula

A floral formula is a way to represent the structure of a flower using specific letters, numbers, and symbols. Typically, a general formula will be used to represent the flower structure of a plant family rather than a particular species. The following representations are used: Ca = calyx (sepal whorl; e.g. Ca⁵ = 5 sepals)
Co = corolla (petal whorl; e.g., Co^3(x) = petals some multiple of three )
Z = add if zygomorphic (e.g., CoZ⁶ = zygomorphic with 6 petals)
A = androecium (whorl of stamens; e.g., A^∞ = many stamens)
G = gynoecium (carpel or carpels; e.g., G¹ = monocarpous)
x - to represent a "variable number"
∞ - to represent "many"
A floral formula would appear something like this: Ca⁵Co⁵A^{10 - ∞}G¹ Several other symbols are used that will have to await drawings to illustrate here (see [http://botit.botany.wisc.edu/courses/systematics/key.html]).

Flower function

family] The function of a flower is to mediate the union of male and female gametes. The process is termed pollination. Many flowers are dependent upon the wind to move pollen between flowers of the same species. Others rely on animals (especially insects) to accomplish this feat. The period of time during which this process can take place (the flower is fully expanded and functional) is called anthesis. Many flowers in nature have evolved to attract animals to pollinate the flower, the movements of the pollinating agent contributing to the opportunity for genetic recombinations within a dispersed plant population. Flowers that are insect pollinated are called entomophilous (literally "insect loving"). Flowers commonly have nectaries on their various parts that attract these animals. Bees and birds are common pollinators: both have color vision, thus selecting for "colorful" flowers. Some flowers have patterns, called nectar guides, that are evident in the ultraviolet range, visible to bees but not to humans. Flowers also attract pollinators by scent. In any case, pollinators are attracted to the plant, perhaps in search of nectar, which they eat. The arrangement of the stamens ensures that pollen grains are transferred to the bodies of the pollinator. In gathering nectar from many flowers of the same species, the pollinators transfer pollen between all of the flowers it visits. Flower scent is not always pleasant to our sense of smell. Some plants, such as Rafflesia, the titan arum, and the North American pawpaw (Asimina triloba) are pollinated by flies, so produce a scent imitating rotting meat. Other flowers are pollinated by the wind, and the flowers of these species (for example, grasses) have no need to attract pollinators and therefore tend not to be "showy". Wind pollinated flowers are referred to as anemophilous. Whereas the pollen of entomophilous flowers tends to be large grained, sticky, and contain significant protein (another "reward" for pollinators), Anemophilous flower pollen is usually small grained, very light, and of little nutritional value to insects, though it may still be gathered, in times of dearth. Honeybees and bumblebees actively gather anemophilous corn (maize) pollen, though it is of little value to them. There is much confusion about the role of flowers in allergies. For example the showy and entomophilous goldenrod (Solidago) is frequently blamed for respiratory allergies, of which it is innocent, since its pollen cannot be airborne. Instead the allergen is usually the pollen of the contemporary bloom of anemophilous ragweed (Ambrosia) which can drift for many kilometers.

Flowers in gardening and horticulture

Main and related articles at: Gardening, Horticulture, List of flowers, and Flower album Flower album

Flowers in the arts

The great variety of delicate and beautiful flowers has inspired the works of many poets, especially from the Romantic era. Famous examples include William Blake's Ah! Sun-Flower and William Wordsworth's I Wandered Lonely as a Cloud. Ah, Sun-flower weary of time,
Who countest the steps of the Sun,
Seeking after that sweet golden clime
Where the traveller's journey is done:

Where the Youth pined away with desire,
And the pale Virgin shrouded in snow
Arise from their graves, and aspire
Where my Sun-flower wishes to go. :– William Blake, Ah! Sun-Flower The Roman goddess of flowers, gardens, and the season of Spring is Flora. The Greek goddess of spring, flowers and nature is Chloris.

Flowers in everyday life

In modern times, people have sought ways to cultivate, buy, wear, or just be around flowers and blooming plants, partly because of their agreeable smell. Around the world, florists sell flowers for a wide range of events and functions that, cumulatively, encompass one's lifetime:
- For new births or Christenings
- As a corsage or boutonniere to be worn at social functions or for holidays
- For wedding flowers for the bridal party, and decorations for the hall
- As brightening decorations within the home
- As a gift of remembrance for bon voyage parties, welcome home parties, and "thinking of you" gifts
- For funeral flowers and flowers for the grieving Florists depend on an entire network of commercial growers and shippers to support this trade. To get flowers that are out of season in their country, florists contact wholesalers who have direct connections with growers in other countries to provide those flowers.

Flowers as symbols

Many flowers have important symbolic meanings in Western culture. The practice of assigning meanings to flowers is known as floriography. Some of the more common examples include:
- Red roses are given as a symbol of love, beauty, and passion.
- Poppies are a symbol of consolation in time of death. In the UK, Australia and Canada, red poppies are worn to commemorate soldiers who have died in times of war.
- Irises are a symbol of death.
- Daisies are a symbol of innocence. Flowers within art are also representative of the female genitalia, as seen in the works of artists such as Georgia O'Keefe, Imogene Cunningham, and Judy Chicago.

References

- Eames, A. J. 1961. Morphology of the Angiosperms. McGraw-Hill Book Co., New York.

External links

- [http://la.essortment.com/floweranatomy_raxw.htm Flower Anatomy]
- [http://www.flowercouncil.org Flower Council of Holland].
- [http://www.lovetoknow.com/Flowers/flowers.htm Flower Encyclopedia]
- [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/Flowering.html Flowering] in [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/ Kimball's Biology Pages]
- [http://www.mystiqueflowers.org Flowers] Flower Types & Meanings
- [http://landscaping.about.com/od/galleryoflandscapephotos/a/flower_pictures.htm Flower Pictures]
- [http://www.flower-arrangement.org Flower Arrangement]
- [http://house-flowers.com House Flowers Council].
- [http://eir.library.utoronto.ca/rpo/display/poem160.html William Blake: Ah Sun-Flower]
- [http://develop.consumerium.org/wiki/index.php/Flowers Flowers] at the Development Wiki of Consumerium Project
- [http://www.lib.ksu.edu/wildflower/drawing/simpleflower.jpg flower schematic]
- [http://www.flowerism.com Flowerism]An artist's devotion to painting of flowers
- [http://800florals.com/care/glossary.asp Glossary of Flowers] - Pictures and Names ---- A flower in a cryptic crossword could be pronounced flo-er and refer to a stream or river.
- Category:Plant anatomy Category: plant morphology Category:Reproductive system zh-min-nan:Hoe ko:꽃 ja:花 simple:Flower th:ดอกไม้

Growing degree day

Growing degree days (GDD) are a heuristic tool in phenology. GDD are used by horticulturists and gardeners to predict the date that a flower will bloom or a crop reach maturity. Absent extreme conditions such as unseasonal drought or disease, plants grow in a cumulative stepwise manner which is strongly influenced by the ambient temperature. Growing degree days take aspects of local weather into account and allow gardeners to predict (or, in greenhouses, even to control) the plants’ pace toward maturity.

GDD calculation

GDD are calculated by taking the average of the daily high and low temperature each day compared to a baseline (usually 10 °C). As an equation; GDD=(((High+Low)/2)-Baseline) GDDs are typically measured from the winter low. For example, a day with a high of 23 °C and a low of 12 °C would contribute 7.5 GDDs. Any temperature below the baseline is set to the baseline before calculating the average. For example, a day with a high of 13 °C and a low of 7 °C would still contribute 1.5 GDDs. Likewise, the maximum temperature is usually capped at 30 °C because most plants and insects do not grow any faster above that temperature. However, some warm temperate and tropical plants do have significant requirements for days above 30 °C to mature fruit or seeds.

Plant development

Selected example GDDs (all in °C base 10 °C):
- Witch-hazel (Hamamelis spp.) - begins flowering at <1 GDD
- Red maple (Acer rubrum), Forsythia spp., Sugar maple (Acer saccharum) - begin flowering at 1-27 GDD
- Norway maple (Acer platanoides), White ash (Fraxinus americana) - begins flowering at 30-50 GDD
- Crabapple (Malus spp.), Common Broom (Cytissus scoparius) - begins flowering at 50-80 GDD
- Horsechestnut (Aesculus hippocastanum), Common lilac (Syringa vulgaris) - begin flowering at 80-110 GDD
- Beach plum (Prunus maritima) - full bloom at 80-110 GDD
- Black locust (Robinia pseudoacacia) - begins flowering at 140-160 GDD
- Catalpa (Catalpa speciosa) - begins flowering at 250-330 GDD
- Privet (Ligustrum spp.), Elderberry (Sambucus canadensis) - begin flowering at 330-400 GDD
- Purple loosestrife (Lythrum salicaria) - begins flowering at at 400-450 GDD
- Sumac (Rhus typhina) - begins flowering at at 450-500 GDD
- Butterfly bush (Buddleia davidii) - begins flowering at at 550-650 GDD
- Corn (maize) - 1360 GDD to crop maturity
- Dry beans - 1100-1300 GDD to maturity depending on cultivar and soil conditions
- Sugar Beets - 130 GDD to emergence and 1400-1500 GDD to maturity
- Barley - 125-162 GDD to emergence and 1290-1540 GDD to maturity
- Wheat (Hard Red) - 143-178 GDD to emergence and 1550-1680 GDD to maturity
- Oats - 1500-1750 GDD to maturity

Insect development and pest control

Growing degree days are also used by some farmers to time their use of pest controls so they are applying the treatment at the point that the pest is most vulnerable. For example:
- Black cutworm larvae have grown large enough to start causing economic damage at 165 GDD
- Azalea Lace Bug emerges at about 130 GDD
- Boxwood leaf miner emerges at about 250 GDD Several beekeepers are now researching the correlation between GDD and the lifecycle of a honeybee colony.

Baselines

10 °C is the most common base for GDD calculations, however, the optimal base is often determined experimentally based on the lifecycle of the plant or insect in question.
- 5.5 °C wheat, barley, rye, oats, flaxseed, lettuce, asparagus
- 6 °C stalk borer moth
- 7 °C Corn Rootworm
- 8 °C sunflower, potato
- 9 °C Alfalfa weevil
- 10 °C maize (including sweet corn), sorghum, rice, soybeans, tomato, Black cutworm, European Corn Borer, standard baseline for insect and mite pests of woody plants
- 11 °C Green Cloverworm
- 12 °C many other crop calculations
- 30 °C the USDA measure heat zones in GDD above 30 °C; for many plants this is significant for seed maturation, e.g. reed (Phragmites) requires at least some days reaching this temperature to mature viable seeds GDDs may be calculated using either Celsius or Fahrenheit, though they must be converted appropriately; 5 GDD^C = 9 GDD^F

External links

- http://ohioline.osu.edu/agf-fact/0101.html
- [http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/cdus/degree_days/grodgree.txt Current year-to-date GDDs for selected US cities]
- [http://www.geog.ubc.ca/courses/klink/g470/class02/apirzade/growingdegrees.htm a table of GDDs necessary for grapes]
- [http://www.montana.edu/wwwpb/pubs/mt200103.html GDDs to various stages of maturity for selected crops]
- [http://www.umassgreeninfo.org/fact_sheets/ipmtools/50_99_GDD.html University of Massachusetts Amherst Extension, Integrated Pest managment Tools, web site accessed Jan 2005]

Fruit

In botany, a fruit is the ripened ovary—together with seeds—of a flowering plant. In many species, the fruit incorporates the ripened ovary and surrounding tissues. Fruits are the means by which flowering plants disseminate seeds. Evolution has led plants to adopt certain basic mechanisms, seemingly without close regard to the tissues involved. No one terminology really fits the enormous variety that is found among plant fruits. Botanical terminology for fruits is inexact and will remain so. In cuisine, when discussing fruit as food, the