Oak is used in winemaking to vary the color, tannin profile and texture of wine. It can be introduced in the form of a barrel during the fermentation or aging periods, or as free-floating chips or staves added to wine fermented in a vessel like stainless steel. Oak barrels can impart other qualities to wine through evaporation and low level exposure to oxygen. In early wine history, the amphora was the vessel of choice for the storage and transportation of wine. Due to the perishable nature of wood material it is difficult to trace the usage of barrels in history; the Greek historian Herodotus noted that ancient Mesopotamians used barrels made of palm wood to transport wine along the Euphrates. Palm is a difficult material to bend and fashion into barrels and wine merchants in different regions experimented with different wood styles to find a better wood source; the use of oak has been prevalent in winemaking for at least two millennia, first coming into widespread use during the time of the Roman Empire.
In time, winemakers discovered that beyond just storage convenience, wine kept in oak barrels took on properties that improved it by making it softer and, in some cases, better-tasting. The porous nature of an oak barrel allows evaporation and oxygenation to occur in wine but not at levels that would cause oxidation or spoilage; the typical 59-gallon barrel can lose anywhere from 51⁄2 to 61⁄2 gallons in a year through evaporation. This allows the wine to concentrate its aroma compounds. Small amounts of oxygen are allowed to pass through the barrel and act as a softening agent upon the wine's tannins; the chemical properties of oak can have a profound effect on wine. Phenols within the wood interact to produce vanilla type flavors and can give the impression of tea notes or sweetness; the degree of "toast" on the barrel can impart different properties affecting the tannin levels as well as the aggressive wood flavors. The hydrolyzable tannins present in wood, known as ellagitannins, are derived from lignin structures in the wood.
They help protect the wine from reduction. Wines can be barrel fermented in oak or placed in oak after fermentation for a period of aging or maturation. Wine matured in oak receives more oak flavors and properties than wine fermented in oak because yeast cells present in fermentation interact with and "latch on" to oak components; when dead yeast cells are removed as lees some oak properties go with them. Characteristics of white wines fermented in oak include extra silky texture. White wines fermented in steel and matured in oak will have a darker coloring due to heavy phenolic compounds still present. Flavor notes used to describe wines exposed to oak include caramel, smoke and vanilla. Chardonnay is a varietal with distinct flavor profiles when fermented in oak, which include coconut and cloves notes; the "toastiness" of the barrel can bring out varying degrees of toffee notes in red wine. The length of time a wine spends in the barrel is dependent on the varietal and finished style the winemaker desires.
The majority of oak flavoring is imparted in the first few months the wine is in contact with oak, while longer term exposure adds light barrel aeration, which helps precipitate phenolic compounds and quickens the aging process. New World Pinot noir may spend less than a year in oak. Premium Cabernet Sauvignon may spend two years; the tannic Nebbiolo grape may spend four or more years in oak. High end Rioja producers will sometimes age their wines up to ten years in American oak to get a desired earthy cedar and herbal character; the species of oak used for American oak production is the Quercus alba, a white oak species, characterized by its fast growth, wider grains and lower wood tannins. It is found in most of the Eastern United States as well as Missouri and Wisconsin where many wine barrels are from. In Oregon the Quercus garryana white oak has started to gain usage due to its closer similarities to European oak. In France, both the Quercus robur and Quercus petraea are considered apt for wine making, the latter is considered far superior for its finer grain and richer contribution of aromatic components like vanillin and its derivates, methyl-octalactone and tannins, as well as phenols and volatile aldehydes.
French oak comes from one or more primary forests: Allier, Nevers, Tronçais and Vosges. The wood from each of these forests has different characteristics. Many winemakers utilize barrels made from different cooperages and degrees of toasting in blending their wines to enhance the complexity of the resulting wine. Italian winemakers have had a long history of using Slavonian oak from the Quercus robur, known for its tight grain, low aromatics and medium level tannins. Slavonian oak tends to be used in larger barrel sizes with the same barrels reused for many more years before replacement. Prior to the Russian Revolution, Quercus petraea oak from the Baltic/European states from Hungary was the most sought after wood for French winemaking; the trees in the Hungarian Zemplén Mountains grow slower in the volcanic soil and smaller, creating fine tight grain which sequentially lends itself to a delicate extraction. The hemicellulose in the Hungarian oak breaks down more and conveys an exceptional selection of toasted, sugary, woody and caramel-like flavors – imparting these aromas with less intensity, slower than American or French oak.
Many winemakers favor the softer, creamier texture that Hungarian oak offers their wines. French winema
Dessert wines, sometimes called pudding wines, are sweet wines served with dessert. There is no simple definition of a dessert wine. In the UK, a dessert wine is considered to be any sweet wine drunk with a meal, as opposed to the white fortified wines drunk before the meal, the red fortified wines drunk after it. Thus, most fortified wines are regarded as distinct from dessert wines, but some of the less strong fortified white wines, such as Pedro Ximénez sherry and Muscat de Beaumes-de-Venise, are regarded as honorary dessert wines. In the United States, by contrast, a dessert wine is defined as any wine over 14% alcohol by volume, which includes all fortified wines - and is taxed more as a result; this dates back to a time when the US wine industry only made dessert wines by fortification, but such a classification is outdated now that modern yeast and viticulture can produce dry wines over 15% without fortification, yet German dessert wines can contain half that amount of alcohol. Examples include Sauternes and Tokaji Aszú.
Makers of dessert wines want to produce a wine containing high levels of both sugar and alcohol, yet the alcohol is made from sugar. There are many ways to increase sugar levels in the final wine: grow grapes so that they have sugar to spare for both sweetness and alcohol. Add sugar, either: before fermentation as sugar or honey after fermentation as unfermented must. Add alcohol before all the sugar is fermented, this is called fortification, or'mutage'. Remove water to concentrate the sugar: In warm climates, by air drying the grapes to make raisin wine In frosty climates, by freezing out some of the water to make ice wine In damp temperate climates, by using a fungal infection, Botrytis cinerea, to desiccate the grapes with noble rot In the absence of other techniques, makers of dessert wine have to produce their sugar in the vineyard; some grape varieties, such as Muscat and Huxelrebe produce a lot more sugar than others. Environmental conditions have a big effect on ultimate sugar levels.
Green harvesting reduces the number of bunches on a vine early in the summer, so that the sugar production of the leaves is divided between fewer bunches. The vigneron cannot control the sun, but a sunny year can help sugar levels a lot; the semi-sweet Auslese wines in the German wine classification are the best example of this approach. But most of the Muscats of ancient times were made this way, including the famous Constantia of South Africa. Honey was added to wine in Roman times, for sweetness and to increase the final strength of the wine. Today sugar is added in order to boost the alcohol levels of flabby, unripe wines rather than for sweetness, although a degree of chaptalization is permitted in the wines of many countries. German wines must declare; the "reserve of sweetness" is a German technique in which unfermented must is added to the wine after fermentation. This increases the sweetness of the final wine, dilutes the alcohol somewhat—in Germany the final wine can contain no more than 15% Süssreserve by volume.
Süssreserve allows winemakers to ferment the wine without having to worry about stopping fermentation before all the sugar has gone. Since sulphites are used to stop fermentation, this technique reduces the usage of sulphites. Süssreserve is used by other makers of German-style wines in New Zealand; the main fortified wines drunk with dessert are sweet sherry Pedro Ximénez, vins doux naturels. The Pedro Ximenez dessert wine is unique because it is a raisin wine, fortified and aged in a solera system like other sherries. Other sweet sherries such as Bristol Cream may be drunk as dessert wine; the production of vins doux naturels was perfected by Arnaud de Villeneuve at the University of Montpellier in the 13th century and they are now quite common in the Languedoc-Roussillon of southwest France. As the names suggest, Muscat de Beaumes-de-Venise, Muscat de Rivesaltes, Muscat de Frontignan, Muscat de Lunel, Muscat de Mireval and Muscat de St-Jean Minervois are all made from the white Muscat grape, whilst Banyuls and Maury are made from red Grenache.
Regardless of the grape, fermentation is stopped with up to 10% of 95% grape spirit. The Muscats are made in a somewhat oxidised style, the Grenaches less so. In ancient Carthage, a sweet wine called passum was made from air-dried grapes, across the Malta Channel from the site of Carthage, similar wines are still made, called Moscato Passito di Pantelleria; such wines were described by the Romans, northern Italy is home to a number of'passito' wines, where the grapes are dried on straw, on racks, or hung from the rafters. These wines include Vin Santo, Sciachetrà, Recioto di Soave and the sweet red Recioto della Valpolicella. Across the Alps, the French make'straw wine' in the Jura and Alsace, the Spanish start off making a raisin wine with Pedro Ximénez before fortifying it, the Cypriots have their ancient Commandaria and there have been recent experiments with the style in South Africa and the USA. Most wine laws require tempera
California wine is wine made in the U. S. state of California. Three quarters the size of France, California accounts for nearly 90 percent of American wine production; the production of wine in California is one third larger than that of Australia. If California were a separate country, it would be the world's fourth largest wine producer; the state's viticultural history dates back to the 18th century when Spanish missionaries planted the first vineyards to produce wine for Mass. Today there are more than 1,200 wineries in the state, ranging from small boutique wineries to large corporations with distribution around the globe; the state of California was first introduced to Vitis vinifera vines, a species of wine grapes native to the Mediterranean region, in the 18th century by the Spanish, who planted vineyards with each mission they established. The wine was used for religious sacraments as well as for daily life; the vine cuttings used to start the vineyards came from Mexico and were the descendant of the "common black grape" brought to the New World by Hernán Cortés in 1520.
The grape's association with the church caused it to become known as the Mission grape, to become the dominant grape variety in California until the 20th century. The California Gold Rush in the mid-19th century brought waves of new settlers to the region, increasing the population and local demand for wine; the newly growing wine industry took hold in Northern California around the counties of Sonoma and Napa. The first commercial winery in California, Buena Vista Winery, was founded in 1857 by Agoston Haraszthy and is located in Sonoma, California. John Patchett opened the first commercial winery in the area, now Napa County in 1859. During this period some of California's oldest wineries were founded including Buena Vista Winery, Gundlach Bundschu, Inglenook Winery, Markham Vineyards and Schramsberg Vineyards. Chinese immigrants played a prominent role in the developing the Californian wine industry during this period - building wineries, planting vineyards, digging the underground cellars and harvesting grapes.
Some assisted as winemakers prior to the passing of the Chinese Exclusion Act which affected the Chinese community in favor of encouraging "white labor." By 1890, most of the Chinese workers were out of the wine industry. The late 19th century saw the advent of the phylloxera epidemic, a type of parasite similar to aphids, which had ravaged France and other European vineyards. Vineyards were destroyed and many smaller operations went out of business. However, the remedy of grafting resistant American rootstock was well known, the Californian wine industry was able to rebound, utilizing the opportunity to expand the plantings of new grape varieties. By the turn of the 20th century nearly 300 grape varieties were being grown in the state, supplying its nearly 800 wineries. Worldwide recognition seemed imminent until January 16, 1919 when the 18th Amendment ushered in the beginning of Prohibition. Vineyards were ordered to be uprooted and cellars were destroyed; some vineyards and wineries were able to survive by converting to table grape or grape juice production.
A few more were able to stay in operation in order to continue to provide churches sacramental wine, an allowed exception to the Prohibition laws. However, most went out of business. By the time that Prohibition was repealed in 1933, only 140 wineries were still in operation, it took time for the Californian wine industry to recover from this setback. By the 1960s, California was known for its sweet port-style wines made from Carignan and Thompson Seedless grapes; however a new wave of winemakers soon emerged and helped usher in a renaissance period in California wine with a focus on new winemaking technologies and emphasizing quality. Several well-known wineries were founded in this decade including Robert Mondavi, Heitz Wine Cellars and David Bruce Winery; as the quality of Californian wine improved, the region started to receive more international attention. A watershed moment for the industry occurred in 1976 when British wine merchant Steven Spurrier invited several Californian wineries to participate in a blind tasting event in Paris.
It was to compare the best of California with the best of Bordeaux and Burgundy - two famous French wine regions. In an event known as The Judgment of Paris, Californian wines shocked the world by sweeping the wine competition in both the red and white wine categories. Throughout the wine world, perspectives about the potential of California wines started to change; the state's wine industry continued to grow as California emerged as one of the world's premier wine regions. In 2010, it was reported for the first time in 16 years; this was not due to a decrease in drinking wine as much as it was a decrease in customers' willingness to spend top dollar on wine. Jon Fredrikson, President of Gomberg, Fredrikson & Associates said that sales of $3 to $6 a bottle wine and $9 to $12 wine had seen growth, but the sales of wine over $20 had stagnated. In addition, most of this loss in market was occurring in overseas sales, as opposed to U. S. sales. California is a geologically diverse region and varies in the range of climates and terroirs that can be found.
Most of the state's wine regions are found between the Central Valley. The Pacific Ocean and large bays, like San Francisco Bay, serve as tempering influences to the wine regions nearby providing cool winds and fog that balance the heat and sunshine. While drought can be a vinicultural hazard, most areas of California receive sufficient amounts of rainfall with the annual rainfall of wine regions north of San Francisco between 24-45 inches and the more southern regions receiving 13-20
Straw wine, or raisin wine, is a wine made from grapes that have been dried to concentrate their juice. The result is suitable for warmer climates; the classic method dries clusters of grapes on mats of straw in the sun, but some regions dry them under cover, on roofs, or on modern racks, while some hang up the grapes or leave them to dry on the vine. The technique dates back to pre-Roman times, most production of these wines has been in Northern Italy and the French Alps; however producers in other areas are now starting to experiment with the method. Straw wines are sweet to sweet white wines, similar in density and sweetness to Sauternes and capable of long life; the low yields and labour-intensive production method means. Around Verona red grapes are dried, are fermented in two different ways to make a dry red wine and a sweet red wine. A dried grape wine known as the Cypriot Manna was described in 800 BC by the Greek poet Hesiod. Similar principles were used to make the medieval Cypriot wine Commandaria, still produced today.
Various Mediterranean raisin wines were described in the first century AD by Columella and Pliny the Elder. Pliny uses the Greek term for honey wine for the following raisin wine, "The grapes are left on the vine to dry in the sun... It is made by drying grapes in the sun, placing them for seven days in a closed place upon hurdles, some seven feet from the ground, care being taken to protect them at night from the dews: on the eighth day they are trodden out: this method, it is said, produces a liquor of exquisite bouquet and flavour; the liquor known as melitites is one of the sweet wines." Columella discusses the Passum wine made in ancient Carthage. The modern Italian name for this wine, echoes this ancient word, as does the French word used to describe the process of producing straw wines, passerillage; the closest thing to passum is Moscato Passito di Pantelleria from Zibibbo, a variety of the ancient muscat grape, produced on Pantelleria, an island in the Strait of Sicily opposite to where Carthage used to be.
Barossa Valley producer, Turkey Flat Vineyards has been experimenting with this style successfully since 2002 with their 100% Marsanne aptly named'The Last Straw'. Air-dried on racks for 6 weeks it is fermented in new oak & now bottle post-fermentation to retain freshness. Residual sugar sits at a comparatively low 59g/l Strohwein or Schilfwein is an Austrian wine term in the Prädikatswein category which designates a straw wine, a sweet dessert wine made from raisin-like dried grapes. Stroh is German for straw; the minimum must weight requirements for Strohwein or Schilfwein is 25 degrees KMW, the same as for Austrian Beerenauslese, these regulations are part of the Austrian wine law. The grapes are furthermore required to be dried for a minimum of three months, either by laying the grape bunches on mats of straw or reed, or by hanging the bunches up for drying by suspending them from pieces of string. However, if the grapes have reached a must weight of at least 30 ºKMW after a minimum of two months, the grapes are allowed to be pressed at this earlier time.
Strohwein and Schilfwein are treated as synonyms by the wine law, the choice between them therefore depends on local naming tradition rather than the specific material used for the drying mats for a specific batch of wine. The Strohwein Prädikat exists only in Austria, not in Germany; the raisin wine most seen in Croatia is Prošek, traditionally from the southern area of Dalmatia. It is made using dried wine grapes in the passito method. There are only a few commercial producers as it is a homemade affair. Slámové víno is the Czech term for straw wine that, under Czech wine law, is classified as a Predicate wine. Czech regulations require the harvested grapes to come from a single wine sub-region, the grapes must be dried for at least three months either on straw or reed mats or hung in a well-ventilated space, the must weight is required to reach at least 27° NM on the Normalizovaný moštomer scale. Straw wine in the Czech Republic is made from white grapes that are well-ripened and undamaged.
Vin de Paille is the French for'straw wine', made only in the ripest vintages. The best known example is made in the Cotes du Jura from a blend of Chardonnay and the red grape Poulsard. Vins de paille are made from Marsanne in Hermitage, from Riesling in Alsace. In Corrèze, it is called Vin Paillé. Traditionally the grapes are placed indoors on straw mats for up to three months, the final wine has 10-20% residual sugar, with flavours of peaches and apricots, it is an excellent accompaniment to foie gras. Some raisin wines are produced in Cyprus. Commandaria claims descent from the native Cypriot wine served at the wedding of King Richard the Lionheart, just after he conquered the island, produced by the Knights Templar at La Grande Commanderie in Cyprus after they purchased it from him, hence claims to be oldest named wine still in production. Commandaria is made from two indigenous grapes, the white Xynisteri and the red Mavro, an ancestor of the Négrette grape known as Pinot St-George in the US.
Vinsanto, the hallmark dessert wine of the island of Santorini, is made of the choicest Assyrtiko grapes, vinified after a few days of sundrying. It is barreled to mature for several years, as its capacity for aging is measured in decades; some varieties of the famed sweet wines of Samos Island are made of sundried Muscat Blanc à Petits
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus Vitis. Grapes can be eaten fresh as table grapes or they can be used for making wine, juice, grape seed extract, raisins and grape seed oil. Grapes are a non-climacteric type of fruit occurring in clusters; the cultivation of the domesticated grape began 6,000–8,000 years ago in the Near East. Yeast, one of the earliest domesticated microorganisms, occurs on the skins of grapes, leading to the discovery of alcoholic drinks such as wine; the earliest archeological evidence for a dominant position of wine-making in human culture dates from 8,000 years ago in Georgia. The oldest known winery was found in Armenia, dating to around 4000 BC. By the 9th century AD the city of Shiraz was known to produce some of the finest wines in the Middle East, thus it has been proposed that Syrah red wine is named after Shiraz, a city in Persia where the grape was used to make Shirazi wine. Ancient Egyptian hieroglyphics record the cultivation of purple grapes, history attests to the ancient Greeks and Romans growing purple grapes for both eating and wine production.
The growing of grapes would spread to other regions in Europe, as well as North Africa, in North America. In North America, native grapes belonging to various species of the genus Vitis proliferate in the wild across the continent, were a part of the diet of many Native Americans, but were considered by early European colonists to be unsuitable for wine. In the 19th century, Ephraim Bull of Concord, cultivated seeds from wild Vitis labrusca vines to create the Concord grape which would become an important agricultural crop in the United States. Grapes are a type of fruit that grow in clusters of 15 to 300, can be crimson, dark blue, green and pink. "White" grapes are green in color, are evolutionarily derived from the purple grape. Mutations in two regulatory genes of white grapes turn off production of anthocyanins, which are responsible for the color of purple grapes. Anthocyanins and other pigment chemicals of the larger family of polyphenols in purple grapes are responsible for the varying shades of purple in red wines.
Grapes are an ellipsoid shape resembling a prolate spheroid. Most grapes come from cultivars of Vitis vinifera, the European grapevine native to the Mediterranean and Central Asia. Minor amounts of fruit and wine come from American and Asian species such as: Vitis amurensis, the most important Asian species Vitis labrusca, the North American table and grape juice grapevines, sometimes used for wine, are native to the Eastern United States and Canada. Vitis mustangensis, found in Mississippi, Louisiana and Oklahoma Vitis riparia, a wild vine of North America, is sometimes used for winemaking and for jam, it is native to the entire Eastern U. S. and north to Quebec. Vitis rotundifolia used for jams and wine, are native to the Southeastern United States from Delaware to the Gulf of Mexico. According to the Food and Agriculture Organization, 75,866 square kilometers of the world are dedicated to grapes. 71% of world grape production is used for wine, 27% as fresh fruit, 2% as dried fruit. A portion of grape production goes to producing grape juice to be reconstituted for fruits canned "with no added sugar" and "100% natural".
The area dedicated to vineyards is increasing by about 2% per year. There are no reliable statistics, it is believed that the most planted variety is Sultana known as Thompson Seedless, with at least 3,600 km2 dedicated to it. The second most common variety is Airén. Other popular varieties include Cabernet Sauvignon, Sauvignon blanc, Cabernet Franc, Grenache, Tempranillo and Chardonnay. Commercially cultivated grapes can be classified as either table or wine grapes, based on their intended method of consumption: eaten raw or used to make wine. While all of them belong to the same species, Vitis vinifera and wine grapes have significant differences, brought about through selective breeding. Table grape cultivars tend to have large, seedless fruit with thin skin. Wine grapes are smaller seeded, have thick skins. Wine grapes tend to be sweet: they are harvested at the time when their juice is 24% sugar by weight. By comparison, commercially produced "100% grape juice", made from table grapes, is around 15% sugar by weight.
Seedless cultivars now make up the overwhelming majority of table grape plantings. Because grapevines are vegetatively propagated by cuttings, the lack of seeds does not present a problem for reproduction, it is an issue for breeders, who must either use a seeded variety as the female parent or rescue embryos early in development using tissue culture techniques. There are several sources of the seedlessness trait, all commercial cultivators get it from one of three sources: Thompson Seedless, Russian Seedless, Black Monukka, all being cultivars of Vitis vinifera. There are more than a dozen varieties of seedless grapes. Several, such as Einset Seedless, Benjamin Gunnels's Prime seedless grapes and Venus, have been cultivated for hardiness and quality in the cold climates of northeastern United States and southern Ontario. An offset to the improved eating quality of seedlessness is the loss of potential health benefits provided by the enriched phytochemical conten
Pollination is the transfer of pollen from a male part of a plant to a female part of a plant enabling fertilisation and the production of seeds, most by an animal or by wind. Pollinating agents are animals such as insects and bats. Pollination occurs within a species; when pollination occurs between species it can produce hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain has landed on the stigma, it develops a pollen tube which grows down the style until it reaches an ovary. Sperm cells from the pollen grain move along the pollen tube, enter an ovum cell through the micropyle and fertilise it, resulting in the production of a seed. A successful angiosperm pollen grain containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary, its two gametes travel down the tube to where the gametophyte containing the female gametes are held within the carpel. One nucleus fuses with the polar bodies to produce the endosperm tissues, the other with the ovule to produce the embryo Hence the term: "double fertilization".
In gymnosperms, the ovule is not contained in a carpel, but exposed on the surface of a dedicated support organ, such as the scale of a cone, so that the penetration of carpel tissue is unnecessary. Details of the process vary according to the division of gymnosperms in question. Two main modes of fertilization are found in gymnosperms. Cycads and Ginkgo have motile sperm that swim directly to the egg inside the ovule, whereas conifers and gnetophytes have sperm that are unable to swim but are conveyed to the egg along a pollen tube; the study of pollination brings together many disciplines, such as botany, horticulture and ecology. The pollination process as an interaction between flower and pollen vector was first addressed in the 18th century by Christian Konrad Sprengel, it is important in horticulture and agriculture, because fruiting is dependent on fertilization: the result of pollination. The study of pollination by insects is known as anthecology. Pollen germination has three stages; the pollen grain is dehydrated so that its mass is reduced enabling it to be more transported from flower to flower.
Germination only takes place after rehydration, ensuring that premature germination does not take place in the anther. Hydration allows the plasma membrane of the pollen grain to reform into its normal bilayer organization providing an effective osmotic membrane. Activation involves the development of actin filaments throughout the cytoplasm of the cell, which become concentrated at the point from which the pollen tube will emerge. Hydration and activation continue. In conifers, the reproductive structures are borne on cones; the cones are either pollen cones or ovulate cones, but some species are monoecious and others dioecious. A pollen cone contains hundreds of microsporangia carried on reproductive structures called sporophylls. Spore mother cells in the microsporangia divide by meiosis to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes; the four resulting cells consist of a large tube cell that forms the pollen tube, a generative cell that will produce two sperm by mitosis, two prothallial cells that degenerate.
These cells comprise a reduced microgametophyte, contained within the resistant wall of the pollen grain. The pollen grains are dispersed by the wind to the female, ovulate cone, made up of many overlapping scales, each protecting two ovules, each of which consists of a megasporangium wrapped in two layers of tissue, the integument and the cupule, that were derived from modified branches of ancestral gymnosperms; when a pollen grain lands close enough to the tip of an ovule, it is drawn in through the micropyle by means of a drop of liquid known as a pollination drop. The pollen enters a pollen chamber close to the nucellus, there it may wait for a year before it germinates and forms a pollen tube that grows through the wall of the megasporangium where fertilisation takes place. During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate; the surviving one develops as a megaspore and divides to form an immature female gametophyte. Two or three archegonia containing an egg develop inside the gametophyte.
Meanwhile, in the spring of the second year two sperm cells are produced by mitosis of the body cell of the male gametophyte. The pollen tube elongates and pierces and grows through the megasporangium wall and delivers the sperm cells to the female gametophyte inside. Fertilisation takes place when the nucleus of one of the sperm cells enters the egg cell in the megagametophyte’s archegonium. In flowering plants, the anthers of the flower produce microspores by meiosis; these undergo mitosis to form male gametophytes. Meanwhile, the ovules produce megaspores by meiosis, further division of these form the female gametophytes, which are strongly reduced, each consisting only of a few cells, one of, the egg; when a pollen grain adheres to the stigma of a carpel it germinates, developing a pollen tube that grows through the tissues of the style, entering the ovule through the micropyle. When the tube reaches the egg sac, two sperm cells pass through it into the female gametophyte and fertil