There are about 380,000 known species of plants, of which the majority, some 260,000, produce seeds. They range in size from single cells to the tallest trees. Green plants provide a substantial proportion of the world's molecular oxygen; the sugars they create supply the energy for most of Earth's ecosystems and other organisms, including animals, either consume plants directly or rely on organisms which do so. (Full article...)
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Cucurbita fruits come in an assortment of colors and sizes.
Cucurbita (Latin for 'gourd') is a genus of herbaceousfruits in the gourd family, Cucurbitaceae (also known as cucurbits or cucurbi), native to the Andes and Mesoamerica. Five edible species are grown and consumed for their flesh and seeds. They are variously known as squash, pumpkin, or gourd, depending on species, variety, and local parlance. Other kinds of gourd, also called bottle-gourds, are native to Africa and belong to the genus Lagenaria, which is in the same family and subfamily as Cucurbita, but in a different tribe. These other gourds are used as utensils or vessels, and their young fruits are eaten much like those of the Cucurbita species.
Most Cucurbita species are herbaceous vines that grow several meters in length and have tendrils, but non-vining "bush" cultivars of C. pepo and C. maxima have also been developed. The yellow or orange flowers on a Cucurbita plant are of two types: female and male. The female flowers produce the fruit and the male flowers produce pollen. Many North and Central American species are visited by specialist beepollinators, but other insects with more general feeding habits, such as honey bees, also visit. (Full article...)
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Acacia pycnantha, most commonly known as the golden wattle, is a tree of the family Fabaceae. It grows to a height of 8 metres (26 feet) and has phyllodes (flattened leaf stalks) instead of true leaves. The profuse fragrant, golden flowers appear in late winter and spring, followed by long seed pods. Explorer Thomas Mitchell collected the type specimen, from which George Bentham wrote the species description in 1842. The species is native to southeastern Australia as an understorey plant in eucalyptus forest. Plants are cross-pollinated by several species of honeyeater and thornbill, which visit nectaries on the phyllodes and brush against flowers, transferring pollen between them.
A. pycnantha has become a weed in areas of Australia, as well as in Africa and Eurasia. Its bark produces more tannin than any other wattle species, resulting in its commercial cultivation for production of this compound. It has been widely grown as an ornamental garden plant and for cut flower production. A. pycnantha was made the official floral emblem of Australia in 1988, and has been featured on the country's postal stamps. (Full article...)
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Inflorescence
Banksia speciosa, commonly known as the showy banksia, is a species of large shrub or small tree in the familyProteaceae. It is found on the south coast of Western Australia between Hopetoun (34° S 120° E) and Point Culver (33° S 124° E), growing on white or grey sand in shrubland. Reaching up to 8 m (26 ft) in height, it is a single-stemmed plant that has thin leaves with prominent triangular 'teeth' along each margin, which are 20–45 cm (7.9–17.7 in) long and 2–4 cm (0.8–1.6 in) wide. The prominent cream-yellow flower spikes known as inflorescences appear throughout the year. As they age they develop up to 20 follicles each that store seeds until opened by fire. Though widely occurring, the species is highly sensitive to dieback and large populations of plants have succumbed to the disease.
Collected and described by Robert Brown in the early 19th century, B. speciosa is classified in the seriesBanksia within the genus. Its closest relative is B. baxteri. B. speciosa plants are killed by bushfire, and regenerate from seed. The flowers attract nectar- and insect-feeding birds, particularly honeyeaters, and a variety of insects. In cultivation, B. speciosa grows well in a sunny location on well-drained soil in areas with dry summers. It cannot be grown in areas with humid summers, though it has been grafted onto Banksia serrata or B. integrifolia. (Full article...)
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A field of iceberg lettuces in California
Lettuce (Lactuca sativa) is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, sandwiches and wraps; it can also be grilled. One variety, celtuce (asparagus lettuce), is grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. , world production of lettuce and chicory was 27 million tonnes, 53percent of which came from China.
Lettuce was originally farmed by the ancient Egyptians, who transformed it from a plant whose seeds were used to obtain oil into an important food crop raised for its succulent leaves and oil-rich seeds. Lettuce spread to the Greeks and Romans; the latter gave it the name lactuca, from which the English lettuce is derived. By 50 AD, many types were described, and lettuce appeared often in medieval writings, including several herbals. The 16th through 18th centuries saw the development of many varieties in Europe, and by the mid-18th century, cultivars were described that can still be found in modern gardens. (Full article...)
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Banksia aculeata, commonly known as prickly banksia, is a species of plant of the family Proteaceae native to the Stirling Range in the southwest of Western Australia. A shrub up to 2 m (7 ft) tall, it has dense foliage and leaves with very prickly serrated margins. Its unusual pinkish, pendent (hanging) flower spikes, known as inflorescences, are generally hidden in the foliage and appear during the early summer. Although it was collected by the naturalist James Drummond in the 1840s, Banksia aculeata was not formally described until 1981, by Alex George in his monograph of the genus.
A rare plant, Banksia aculeata is found in gravelly soils in elevated areas. Native to a habitat burnt by periodic bushfires, it is killed by fire and regenerates from seed afterwards. In contrast to other Western Australian banksias, it appears to have some resistance to the soil-borne water mouldPhytophthora cinnamomi. (Full article...)
Banksia aemula, commonly known as the wallum banksia, is a shrub of the family Proteaceae. Found from Bundaberg south to Sydney on the Australian east coast, it is encountered as a shrub or a tree to 8 m (26 ft) in coastal heath on deep sandy soil, known as Wallum. It has wrinkled orange bark and shiny green serrated leaves, with green-yellow flower spikes, known as inflorescences, appearing in autumn. The flower spikes turn grey as they age and large grey follicles appear. Banksia aemula resprouts from its woody base, known as a lignotuber, after bushfires.
First described by the botanist Robert Brown in the early 19th century, it derives its specific name 'similar' from its resemblance to the closely related B. serrata. No varieties are recognised. It was known for many years in New South Wales as B. serratifolia, contrasting with the use of B. aemula elsewhere. However, the former name, originally coined by Richard Anthony Salisbury, proved invalid, and Banksia aemula has been universally adopted as the correct scientific name since 1981. A wide array of mammals, birds, and invertebrates visit the inflorescences and are instrumental in pollination; honeyeaters are particularly prominent visitors. Grown as a garden plant, it is less commonly seen in horticulture than its close relative B. serrata. (Full article...)
Banksia aquilonia, commonly known as the northern banksia and jingana, is a tree in the familyProteaceae and is endemic to north Queensland on Australia's northeastern coastline. With an average height of 8 m (26 ft), it has narrow glossy green leaves up to 20 cm (7.9 in) long and 6 to 10 cm (2.4 to 3.9 in) high pale yellow flower spikes, known as inflorescences, appearing in autumn. As the spikes age, their flowers fall off and they develop up to 50 follicles, each of which contains two seeds.
Banksia lemanniana, the yellow lantern banksia or Lemann's banksia, is a species of flowering plant in the familyProteaceae, native to Western Australia. It generally grows as an open woody shrub or small tree to 5 m (16 ft) high, with stiff serrated leaves and unusual hanging inflorescences. Flowering occurs over summer, the greenish buds developing into oval flower spikes before turning grey and developing the characteristic large woody follicles. It occurs within and just east of the Fitzgerald River National Park on the southern coast of the state. B. lemanniana is killed by bushfire and regenerates from seed.
Described by Swiss botanist Carl Meissner in 1856, Banksia lemanniana was named in honour of English botanist Charles Morgan Lemann. It is one of three or four related species all with pendent inflorescences, which is an unusual feature of banksias. No subspecies are recognised. Banksia lemanniana is classified as Not Threatened under the Wildlife Conservation Act of Western Australia. Unlike many Western Australian banksias, it appears to have some resistance to dieback from the soil-borne water mouldPhytophthora cinnamomi, and is one of the easier Western Australian species to grow in cultivation. (Full article...)
The tree grows rapidly, and is capable of reaching heights of 15 metres (50 ft) in 25 years. While the species rarely lives more than 50 years, some specimens exceed 100 years of age. Its suckering ability allows this tree to clone itself indefinitely. It is considered a noxious weed and vigorous invasive species, and one of the worst invasive plant species in Europe and North America. In 21st-century North America, the invasiveness of the species has been compounded by its role in the life cycle of the also destructive and invasive spotted lanternfly. (Full article...)
Banksia serrata, commonly known as the saw banksia, the old man banksia, the saw-tooth banksia or the red honeysuckle and as wiriyagan by the Cadigal people, is a species of woody shrub or tree of the genus Banksia, in the family Proteaceae. Native to the east coast of Australia, it is found from Queensland to Victoria with outlying populations on Tasmania and Flinders Island. Commonly growing as a gnarled tree up to 16 m (50 ft) in height, it can be much smaller in more exposed areas. This Banksia species has wrinkled grey bark, shiny dark green serrated leaves and large yellow or greyish-yellow flower spikes appearing over summer. The flower spikes, or inflorescences, turn grey as they age and pollinated flowers develop into large, grey, woody seed pods called follicles.
B. serrata is one of the four original Banksia species collected by Sir Joseph Banks in 1770, and one of four species published in 1782 as part of Carolus Linnaeus the Younger's original description of the genus. There are no recognised varieties, although it is closely related to Banksia aemula. Throughout its range, it grows exclusively in sandy soil, and is usually the dominant plant in scrubland or low woodland. B. serrata is pollinated by and provides food for a wide array of vertebrate and invertebrate animals in the autumn and winter months, and is an important source of food for honeyeaters. It is a common plant of parks and gardens. (Full article...)
The fruits are small, round, and yellow, and can ripen and turn red at any time of year, peaking in spring and summer. Like all figs, the fruit is in the form of a syconium, an inverted inflorescence with the flowers lining an internal cavity. F. rubiginosa is exclusively pollinated by the fig wasp species Pleistodontes imperialis, which may comprise four cryptospecies. The syconia are also home to another fourteen species of wasp, some of which induce galls while others parasitise the pollinator wasps and at least two species of nematode. Many species of bird, including pigeons, parrots, and various passerines, eat the fruit. Ranging along the Australian east coast from Queensland to Bega in southern New South Wales (including the Port Jackson area, leading to its alternative name), F. rubiginosa grows in rainforest margins and rocky outcrops. It is used as a shade tree in parks and public spaces, and when potted is well-suited for use as an indoor plant or in bonsai. (Full article...)
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The title page of the 1877 edition of Fertilisation of Orchids
Fertilisation of Orchids is a book by English naturalist Charles Darwin published on 15 May 1862 under the full explanatory title On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and On the Good Effects of Intercrossing. Darwin's previous book, On the Origin of Species, had briefly mentioned evolutionary interactions between insects and the plants they fertilised, and this new idea was explored in detail. Field studies and practical scientific investigations that were initially a recreation for Darwin—a relief from the drudgery of writing—developed into enjoyable and challenging experiments. Aided in his work by his family, friends, and a wide circle of correspondents across Britain and worldwide, Darwin tapped into the contemporary vogue for growing exotic orchids.
The book was his first detailed demonstration of the power of natural selection, and explained how complex ecological relationships resulted in the coevolution of orchids and insects. The view has been expressed that the book led directly or indirectly to all modern work on coevolution and the evolution of extreme specialisation. It influenced botanists, and revived interest in the neglected idea that insects played a part in pollinating flowers. It opened up the new study areas of pollination research and reproductive ecology, directly related to Darwin's ideas on evolution, and supported his view that natural selection led to a variety of forms through the important benefits achieved by cross-fertilisation. Although the general public showed less interest and sales of the book were low, it established Darwin as a leading botanist. Orchids was the first in a series of books on his innovative investigations into plants. (Full article...)
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McClintock in her laboratory, 1947
Barbara McClintock (June 16, 1902 – September 2, 1992) was an American scientist and cytogeneticist who was awarded the 1983 Nobel Prize in Physiology or Medicine. McClintock received her PhD in botany from Cornell University in 1927. There she started her career as the leader of the development of maize cytogenetics, the focus of her research for the rest of her life. From the late 1920s, McClintock studied chromosomes and how they change during reproduction in maize. She developed the technique for visualizing maize chromosomes and used microscopic analysis to demonstrate many fundamental genetic ideas. One of those ideas was the notion of genetic recombination by crossing-over during meiosis—a mechanism by which chromosomes exchange information. She produced the first genetic map for maize, linking regions of the chromosome to physical traits. She demonstrated the role of the telomere and centromere, regions of the chromosome that are important in the conservation of genetic information. She was recognized as among the best in the field, awarded prestigious fellowships, and elected a member of the National Academy of Sciences in 1944.
During the 1940s and 1950s, McClintock discovered transposons and used it to demonstrate that genes are responsible for turning physical characteristics on and off. She developed theories to explain the suppression and expression of genetic information from one generation of maize plants to the next. Due to skepticism of her research and its implications, she stopped publishing her data in 1953. (Full article...)
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Second-year plant starting to flower, with a dead stem of the previous year, behind left
Verbascum thapsus, the great mullein, greater mullein or common mullein, is a species of mullein native to Europe, northern Africa, and Asia, and introduced in the Americas and Australia.
It is a hairy biennial plant that can grow to 2 m tall or more. Its small, yellow flowers are densely grouped on a tall stem, which grows from a large rosette of leaves. It grows in a wide variety of habitats, but prefers well-lit, disturbed soils, where it can appear soon after the ground receives light, from long-lived seeds that persist in the soil seed bank. It is a common weedy plant that spreads by prolifically producing seeds, and has become invasive in temperate world regions. It is a minor problem for most agricultural crops, since it is not a competitive species, being intolerant of shade from other plants and unable to survive tilling. It also hosts many insects, some of which can be harmful to other plants. Although individuals are easy to remove by hand, populations are difficult to eliminate permanently. (Full article...)
Cotyledon from a Judas-tree (Cercis siliquastrum, a dicot) seedling A cotyledon (/ˌkɒtɪˈliːdən/; from Latincotyledon; from κοτυληδών (kotulēdṓn) "a cavity, small cup, any cup-shaped hollow", gen. κοτυληδόνος (kotulēdónos), from κοτύλη (kotýlē) 'cup, bowl') is a "seed leaf" - a significant part of the embryo within the seed of a plant, and is formally defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed." Botanists use the number of cotyledons present as one characteristic to classify the flowering plants (angiosperms): species with one cotyledon are called monocotyledonous ("monocots"); plants with two embryonic leaves are termed dicotyledonous ("dicots").
In the case of dicot seedlings whose cotyledons are photosynthetic, the cotyledons are functionally similar to leaves. However, true leaves and cotyledons are developmentally distinct. Cotyledons form during embryogenesis, along with the root and shoot meristems, and are therefore present in the seed prior to germination. True leaves, however, form post-embryonically (i.e. after germination) from the shoot apical meristem, which generates subsequent aerial portions of the plant. (Full article...)
Fruit tree propagation is usually carried out vegetatively (non-sexually) by grafting or budding a desired variety onto a suitable rootstock.
Perennial plants can be propagated either by sexual or vegetative means. Sexual reproduction begins when a male germ cell (pollen) from one flower fertilises a female germ cell (ovule, incipient seed) of the same species, initiating the development of a fruit containing seeds. Each seed, when germinated, can grow to become a new specimen tree. However, the new tree inherits characteristics of both its parents, and it will not grow true to the variety of either parent from which it came. That is, it will be a fresh individual with an unpredictable combination of characteristics of its own. Although this is desirable in terms of producing novel combinations from the richness of the gene pool of the two parent plants (such sexual recombination is the source of new cultivars), only rarely will the resulting new fruit tree be directly useful or attractive to the tastes of humankind. Most new plants will have characteristics that lie somewhere between those of the two parents. (Full article...)
The family has a cosmopolitan distribution. The enlarged Lamiaceae contain about 236 genera and have been stated to contain 6,900 to 7,200 species, but the World Checklist lists 7,534. The largest genera are Salvia (900), Scutellaria (360), Stachys (300), Plectranthus (300), Hyptis (280), Teucrium (250), Vitex (250), Thymus (220), and Nepeta (200). Clerodendrum was once a genus of over 400 species, but by 2010, it had been narrowed to about 150. (Full article...)
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A tropical plant community on Diego Garcia Plant ecology is a subdiscipline of ecology that studies the distribution and abundance of plants, the effects of environmental factors upon the abundance of plants, and the interactions among plants and between plants and other organisms. Examples of these are the distribution of temperate deciduous forests in North America, the effects of drought or flooding upon plant survival, and competition among desert plants for water, or effects of herds of grazing animals upon the composition of grasslands.
A global overview of the Earth's major vegetation types is provided by O.W. Archibold. He recognizes 11 major vegetation types: tropical forests, tropical savannas, arid regions (deserts), Mediterranean ecosystems, temperate forest ecosystems, temperate grasslands, coniferous forests, tundra (both polar and high mountain), terrestrial wetlands, freshwater ecosystems and coastal/marine systems. This breadth of topics shows the complexity of plant ecology, since it includes plants from floating single-celled algae up to large canopy forming trees. (Full article...)
Prunus is a genus of trees and shrubs in the flowering plant family Rosaceae that includes plums, cherries, peaches, nectarines, apricots, and almonds. The genus has a cosmopolitan distribution, being native to the North American temperate regions, the neotropics of South America, and temperate and tropical regions of Asia and Africa, There are about 340 accepted species . Many members of the genus are widely cultivated for their fruit and for decorative purposes. Prunus fruit are drupes, or stone fruits. The fleshy mesocarp surrounding the endocarp is edible while the endocarp itself forms a hard, inedible shell called the pyrena ("stone" or "pit"). This shell encloses the seed (or "kernel"), which is edible in some species (such as sweet almonds), but poisonous in many others (such as apricot kernels). Besides being eaten off the hand, most Prunus fruit are also commonly used in processing, such as jam production, canning, drying, and the seeds for roasting. (Full article...)
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A late Siluriansporangium, artificially colored. Green: A spore tetrad. Blue: A spore bearing a trilete mark – the Y-shaped scar. The spores are about 30–35 μm across.
The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats of unicellular archaeplastids evolved through endosymbiosis, through multicellular marine and freshwatergreen algae, to spore-bearing terrestrial bryophytes, lycopods and ferns, and eventually to the complex seed-bearing gymnosperms and angiosperms (flowering plants) of today. While many of the earliest groups continue to thrive, as exemplified by red and green algae in marine environments, more recently derived groups have displaced previously ecologically dominant ones; for example, the ascendance of flowering plants over gymnosperms in terrestrial environments.
There is evidence that cyanobacteria and multicellular thalloid eukaryotes lived in freshwater communities on land as early as 1 billion years ago, and that communities of complex, multicellular photosynthesizing organisms existed on land in the late Precambrian, around 850 million years ago. (Full article...)
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Ethylene chemical structure. Ethylene signaling pathway is a signal transduction in plant cells to regulate important growth and developmental processes. Acting as a plant hormone, the gas ethylene is responsible for promoting the germination of seeds, ripening of fruits, the opening of flowers, the abscission (or shedding) of leaves and stress responses. It is the simplest alkene gas and the first gaseous molecule discovered to function as a hormone.
Most of the understanding on ethylene signal transduction come from studies on Arabidopsis thaliana. Ethylene can bind to at least five different membrane gasoreceptors. Although structurally diverse, the ethylene gasoreceptors all exhibit similarity (homology) to two-component regulatory system in bacteria, indicating their common ancestry from bacterial ancestor. Ethylene binds to the gasoreceptors on the cell membrane of the endoplasmic reticulum. Although homodimers of the gasoreceptors are required for functional state, only one ethylene molecule binds to each dimer. (Full article...)
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Acclimatisation societies were voluntary associations, founded in the 19th and 20th centuries, that encouraged the introduction of non-native species in various places around the world, in the hope that they would acclimatise and adapt to their new environments. The societies formed during the colonial era, when Europeans began to settle in numbers in unfamiliar locations. One motivation for the activities of the acclimatisation societies was that introducing new species of plants and animals (mainly from Europe) would enrich the flora and fauna of target regions. The movement also sought to establish plants and animals that were familiar to Europeans, while also bringing exotic and useful foreign plants and animals to centres of European settlement.
The olive, botanical name Olea europaea, meaning 'European olive', is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as Olea europaea'Montra', dwarf olive, or little olive. The species is cultivated in all the countries of the Mediterranean, as well as in Australia, New Zealand, North and South America and South Africa. It is the type species for its genus, Olea. The tree and its fruit give their name to the Oleaceae plant family, which also includes species such as lilac, jasmine, forsythia, and the true ash tree.
The olive's fruit, also called an "olive", is of major agricultural importance in the Mediterranean region as the source of olive oil; it is one of the core ingredients in Middle Easternand Mediterranean cuisines. Thousands of cultivars of the olive tree are known. Olive cultivars may be used primarily for oil, eating, or both. Olives cultivated for consumption are generally referred to as "table olives". About 80% of all harvested olives are turned into oil, while about 20% are used as table olives. (Full article...)
The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, that the seed has two embryonic leaves or cotyledons. There are around 200,000 species within this group. The other group of flowering plants were called monocotyledons (or monocots), typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.
Largely from the 1990s onwards, molecular phylogenetic research confirmed what had already been suspected: that dicotyledons are not a group made up of all the descendants of a common ancestor (i.e., they are not a monophyletic group). Rather, a number of lineages, such as the magnoliids and groups now collectively known as the basal angiosperms, diverged earlier than the monocots did; in other words, monocots evolved from within the dicots, as traditionally defined. The traditional dicots are thus a paraphyletic group. (Full article...)
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A European honey bee pollinates a peach flower while collecting nectar. Pollination of fruit trees is required to produce seeds with surrounding fruit. It is the process of moving pollen from the anther to the stigma, either in the same flower or in another flower. Some tree species, including many fruit trees, do not produce fruit from self-pollination, so pollinizer trees are planted in orchards.
The pollination process requires a carrier for the pollen, which can be animal, wind, or human intervention (by hand-pollination or by using a pollen sprayer). Cross pollination produces seeds with a different genetic makeup from the parent plants; such seeds may be created deliberately as part of a selective breeding program for fruit trees with desired attributes. Trees that are cross-pollinated or pollinated via an insect pollinator produce more fruit than trees with flowers that just self-pollinate. In fruit trees, bees are an essential part of the pollination process for the formation of fruit. (Full article...)
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The sunflower was one of the plants that made up the Eastern Agricultural Complex. The Eastern Agricultural Complex in the woodlands of eastern North America was one of about 10 independent centers of plant domestication in the pre-historic world. Incipient agriculture dates back to about 5300 BCE. By about 1800 BCE the Native Americans of the woodlands were cultivating several species of food plants, thus beginning a transition from a hunter-gatherer economy to agriculture. After 200 BCE when maize from Mexico was introduced to the Eastern Woodlands, the Native Americans of the eastern United States and adjacent Canada slowly changed from growing local indigenous plants to a maize-based agricultural economy. The cultivation of local indigenous plants other than squash and sunflower declined and was eventually abandoned. The formerly domesticated plants returned to their wild forms.
In botany, a perennial plant or simply perennial is a plant that lives more than two years. The term (per- + -ennial, "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widely used to distinguish plants with little or no woody growth (secondary growth in girth) from trees and shrubs, which are also technically perennials. Notably, it is estimated that 94% of plant species fall under the category of perennials, underscoring the prevalence of plants with lifespans exceeding two years in the botanical world.
Perennials—especially small flowering plants—that grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock or other overwintering structure, are known as herbaceous perennials. However, depending on the rigours of the local climate (temperature, moisture, organic content in the soil, microorganisms), a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings, or from divisions. Tomato vines, for example, live several years in their natural tropical/subtropical habitat but are grown as annuals in temperate regions because their above-ground biomass does not survive the winter. (Full article...)
Vavilov's work was criticized by Trofim Lysenko, whose anti-Mendelian concepts of plant biology had won favor with Joseph Stalin. As a result, Vavilov was arrested and subsequently sentenced to death in July 1941. Although his sentence was commuted to twenty years' imprisonment, he died in prison in 1943. In 1955, his death sentence was retroactively pardoned under Nikita Khrushchev. By the late 1950s, his reputation was publicly rehabilitated, and he began to be hailed as a hero of Soviet science. (Full article...)
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North American beaver dam in Tierra del Fuego An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food web. Since the 20th century, invasive species have become a serious economic, social, and environmental threat worldwide.
Rapaza viridis is the first known mixotroph (an organism that combines photosynthesis and ingestion of food) and kleptoplastic species within the phylumEuglenozoa. It eats microalgae by engulfing them—a process called phagocytosis—and then uses the chloroplasts from these algae to perform photosynthesis, altering the chloroplasts' structure in the process. In particular, Rapaza viridis can only feed on Tetraselmis cells native to their original environment, and will reject any other prey. (Full article...)
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Manihot esculenta, commonly calledcassava, manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America, from Brazil, Paraguay and parts of the Andes. Although a perennial plant, cassava is extensively cultivated in tropical and subtropical regions as an annual crop for its edible starchy root tuber. Cassava is predominantly consumed in boiled form, but substantial quantities are processed to extract cassava starch, called tapioca, which is used for food, animal feed, and industrial purposes. The Brazilian farinha, and the related garri of West Africa, is an edible coarse flour obtained by grating cassava roots, pressing moisture off the obtained grated pulp, and finally drying it (and roasting in the case of both farinha and garri).
Cassava is the third-largest source of carbohydrates in food in the tropics, after rice and maize, making it an important staple; more than 500 million people depend on it. It offers the advantage of being exceptionally drought-tolerant, and able to grow productively on poor soil. The largest producer is Nigeria, while Thailand is the largest exporter of cassava starch. (Full article...)
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The Webster Sycamore (alternatively known as the Webster Springs Sycamore and the Big Sycamore Tree) was an American sycamore (Platanus occidentalis) in the U.S. state of West Virginia. Long recognized for its size, the Webster Sycamore was the largest living American sycamore tree in West Virginia until its felling in 2010. The tree stood approximately 4.5 miles (7.2 km) east of Webster Springs in Webster County, in a moist flood plain along the banks of the Back Fork Elk River, a tributary stream of the Elk River.
The Webster Sycamore reached a tree height measurement of 112 feet (34 m), a tree crown measurement of 90 feet (27 m), and a circumference of 25.75 feet (7.85 m) at breast height. In 1955, the American Forests Association declared the tree the largest of its species in the United States. It only held the title for three weeks, before the association identified a larger American sycamore in Maryland. Despite losing its national title, the sycamore remained the largest American sycamore in West Virginia. Following a 1963 survey of large trees in West Virginia, the Webster Sycamore was named the second-largest tree after a white oak (Quercus alba) in Randolph County. (Full article...)
The Flora Antarctica, or formally and correctly The Botany of the Antarctic Voyage of H.M. Discovery Ships Erebus and Terror in the years 1839–1843, under the Command of Captain Sir James Clark Ross, is a description of the many plants discovered on the Ross expedition, which visited islands off the coast of the Antarctic continent, with a summary of the expedition itself, written by the British botanistJoseph Dalton Hooker and published in parts between 1844 and 1859 by Reeve Brothers in London. Hooker sailed on HMS Erebus as assistant surgeon.
The botanical findings of the Ross expedition were published in four parts, the last two in two volumes each, making six volumes in all: (Full article...)
Hypericum aegypticum is a species of flowering plant of the St. John's wort family (Hypericaceae) which is native to the Eastern Mediterranean. It was described by Carl Linnaeus in the second volume of his Species Plantarum in 1753, who named it after Egypt despite it not being distributed there. The plant is commonly known as shrubby St. John's wort or Egyptian St. John's wort in English. Like other members of section Adenotrias, it is found among limestone rocks in coastal areas. While it has been evaluated as threatened on the island of Malta, the species has no legal protections.
The species is a shrub or shrublet that grows up to 2 meters (6.5 feet) tall with many branches, each having a single small flower with five yellow petals and many stamens. Its leaves lack hairs, and have densely patterned glands and large primary veins. The species is notable for its heterostyly, a trait which within the Hypericum genus is unique to section Adenotrias, and exhibits one of two heterostylous flower types called "pins" and "thrums". It has three subspecies, which vary in their distribution and phytochemical makeup. (Full article...)
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Various Cactaceae from Brockhaus' Konversations-Lexikon v. 2 1892
A cactus (pl.: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (/kæˈkteɪsiaɪ,-siːiː/), a family comprising about 127 genera with some 1,750 known species of the order Caryophyllales. The word cactus derives, through Latin, from the Ancient Greek word κάκτος (káktos), a name originally used by Theophrastus for a spiny plant whose identity is now not certain. Cacti occur in a wide range of shapes and sizes. They are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north, with the exception of Rhipsalis baccifera, which is also found in Africa and Sri Lanka. Cacti are adapted to live in very dry environments, including the Atacama Desert, one of the driest places on Earth. Because of this, cacti show many adaptations to conserve water. For example, almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. Most species of cacti have lost true leaves, retaining only spines, which are highly modified leaves. As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of true leaves, cacti's enlarged stems carry out photosynthesis.
Cactus spines are produced from specialized structures called areoles, a kind of highly reduced branch. Areoles are an identifying feature of cacti. As well as spines, areoles give rise to flowers, which are usually tubular and multipetaled. Many cacti have short growing seasons and long dormancies and are able to react quickly to any rainfall, helped by an extensive but relatively shallow root system that quickly absorbs any water reaching the ground surface. Cactus stems are often ribbed or fluted with a number of ribs which corresponds to a number in the Fibonacci numbers (2, 3, 5, 8, 13, 21, 34 etc.). This allows them to expand and contract easily for quick water absorption after rain, followed by retention over long drought periods. Like other succulent plants, most cacti employ a special mechanism called "crassulacean acid metabolism" (CAM) as part of photosynthesis. Transpiration, during which carbon dioxide enters the plant and water escapes, does not take place during the day at the same time as photosynthesis, but instead occurs at night. The plant stores the carbon dioxide it takes in as malic acid, retaining it until daylight returns, and only then using it in photosynthesis. Because transpiration takes place during the cooler, more humid night hours, water loss is significantly reduced. (Full article...)
E. reichenbachii is one of the smaller Echinocereus species. They reach 7.5 to 30 centimetres (3.0 to 11.8 in) tall and 4 to 10 centimetres (1.6 to 3.9 in) wide. Plants are solitary or clustered in as many as 12, with erect stems that have 10 to 19 ribs. The stems are dark green and often obscured by the spines, which range from tan, brown, black, or pink, and the tips are usually darker than the shaft. The areoles are elliptical or oval, with seven to 36 spines each. The purple or pink flowers bloom in early May to late June, growing to approximately 4.5 to 8 centimetres (1.8 to 3.1 in) by 5 to 10 centimetres (2.0 to 3.9 in). E. reichenbachii are cold and heat tolerant, and prefer dry, well-drained soils near rock outcroppings. (Full article...)
Wild species of cherry tree are widely distributed, mainly in the Northern Hemisphere. They are common in East Asia, especially in Japan, where they have been cultivated, producing many varieties. (Full article...)
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Einar Du Rietz in 1932
Gustaf Einar Du Rietz (25 April 1895 – 7 March 1967) was a Swedish botanist and lichenologist. His research interests included plant ecology, lichen taxonomy, and biogeography. He was a leading figure in the Uppsala school of phytosociology–the study of groups of species of plants that are usually found together–and is recognised for his role in advancing this field of science and for mentoring future lichenologists. He led the Swedish Australasian Botanical Expedition of 1926–27, a seven-month research tour of various locations. He was married to Greta Sernander, who was also a lichenologist. During the expedition, Du Rietz and his wife researched the vegetation in New Zealand, Australia, and Java, focusing on mountain lichens and their potential as bioindicators for environmental conditions. They collected around 3000 specimens, contributing significantly to the study of bipolar lichens and forest ecology, despite challenges in processing all the samples upon return to Sweden. Several species have been named in his honour. In 1949, Du Rietz was elected to the Royal Swedish Academy of Sciences and contributed significantly to nature conservation efforts in Sweden. (Full article...)
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Fossils of A. longicervia described in Wong et al. (2015)
The species was originally described as a pitcher plant with close affinities to extant members of the familySarraceniaceae. This would make it the earliest known carnivorous plant and the only known fossil record of Sarraceniaceae, or the New World pitcher plant family. Archaeamphora is also one of the three oldest known genera of angiosperms (flowering plants). Li (2005) wrote that "the existence of a so highly derived Angiosperm in the Early Cretaceous suggests that Angiosperms should have originated much earlier, maybe back to 280 mya as the molecular clock studies suggested". (Full article...)
Eucalyptus wandoo, commonly known as wandoo, dooto, warrnt or wornt and sometimes as white gum, is a small to medium-sized tree that is endemic to the southwest of Western Australia. It has smooth bark, lance-shaped adult leaves, flower buds in groups of nine to seventeen, white flowers and conical to cylindrical fruit. It is one of a number of similar Eucalyptus species known as wandoo.
... that ochrophyte algae have twice as many membranes around their chloroplasts as plants?
... that according to Lois N. Magner, Hildegard of Bingen's Physica is "probably the first book by a female author to discuss the elements and the therapeutic virtues of plants, animals, and metals"?
Image 6Echeveria glauca in a Connecticut greenhouse. Botany uses Latin names for identification; here, the specific name glauca means blue. (from Botany)
Image 7Thale cress, Arabidopsis thaliana, the first plant to have its genome sequenced, remains the most important model organism. (from Botany)
Image 15The evolution of syncarps. a: sporangia borne at tips of leaf b: Leaf curls up to protect sporangia c: leaf curls to form enclosed roll d: grouping of three rolls into a syncarp (from Evolutionary history of plants)
Image 16The trunk of early tree fern Psaronius, showing internal structure. The top of the plant would have been to the left of the image (from Evolutionary history of plants)
Image 19The Devonian marks the beginning of extensive land colonization by plants, which – through their effects on erosion and sedimentation – brought about significant climatic change. (from Evolutionary history of plants)
Image 241 An oat coleoptile with the sun overhead. Auxin (pink) is evenly distributed in its tip. 2 With the sun at an angle and only shining on one side of the shoot, auxin moves to the opposite side and stimulates cell elongation there. 3 and 4 Extra growth on that side causes the shoot to bend towards the sun. (from Botany)
Image 27Structure of a plant cell (from Plant cell)
Image 28A nineteenth-century illustration showing the morphology of the roots, stems, leaves and flowers of the rice plant Oryza sativa (from Botany)
Image 29A banded tube from the Late Silurian/Early Devonian. The bands are difficult to see on this specimen, as an opaque carbonaceous coating conceals much of the tube. Bands are just visible in places on the left half of the image. Scale bar: 20 μm (from Evolutionary history of plants)
Image 30Transverse section of a fossil stem of the Devonian vascular plant Rhynia gwynne-vaughani (from Botany)
Image 31The food we eat comes directly or indirectly from plants such as rice. (from Botany)
Image 32The fruit of Myristica fragrans, a species native to Indonesia, is the source of two valuable spices, the red aril (mace) enclosing the dark brown nutmeg. (from Botany)
Image 33The Linnaean Garden of Linnaeus' residence in Uppsala, Sweden, was planted according to his Systema sexuale. (from Botany)
Image 34Structure of Azadirachtin, a terpenoid produced by the Neem plant, which helps ward off microbes and insects. Many secondary metabolites have complex structures (from Evolutionary history of plants)
Image 35A late Siluriansporangium, artificially colored. Green: A spore tetrad. Blue: A spore bearing a trilete mark – the Y-shaped scar. The spores are about 30–35 μm across. (from Evolutionary history of plants)
Image 36Micropropagation of transgenic plants (from Botany)
Image 37The branching pattern of megaphyll veins may indicate their origin as webbed, dichotomising branches. (from Evolutionary history of plants)