Indeterminate growth
In biology and botany, indeterminate growth is growth, not terminated in contrast to determinate growth that stops once a genetically pre-determined structure has formed. Thus, a plant that grows and produces flowers and fruit until killed by frost or some other external factor is called indeterminate. For example, the term is applied to tomato varieties that grow in a rather gangly fashion, producing fruit throughout the growing season, in contrast to a determinate tomato plant, which grows in a more bushy shape and is most productive for a single, larger harvest either tapers off with minimal new growth or fruit, or dies. In reference to an inflorescence, an indeterminate type is one in which the first flowers to develop and open are from the buds at the base, followed progressively by buds nearer to the growing tip; the growth of the shoot is not impeded by the opening of the early flowers or development of fruits and its appearance is of growing and maturing flowers and fruit indefinitely.
In practice the continued growth of the terminal end peters out sooner or though without producing any definite terminal flower, in some species it may stop growing before any of the buds have opened. Not all plants produce indeterminate inflorescences however. In most species that produce a'determinate inflorescence in this way, all of the flower buds are formed before the first ones begin to open, all open more or less at the same time. In some species with determinate inflorescences however, the terminal flower blooms first, which stops the elongation of the main axis, but side buds develop lower down. One type of example is Dianthus. In zoology, indeterminate growth refers to the condition where animals grow when young, continue to grow after reaching adulthood although at a slower pace, it is common in fish, amphibians and many molluscs. The term refers to the pattern of hair growth sometimes seen in humans and a few domestic breeds, where hair continues to grow in length until it is cut.
Some mushrooms – notably Cantharellus californicus – exhibit indeterminate growth. Determinate cultivar
Epiphyte
An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, water or from debris accumulating around it. Epiphytes take part in nutrient cycles and add to both the diversity and biomass of the ecosystem in which they occur, like any other organism, they are an important source of food for many species. The older parts of a plant will have more epiphytes growing on them. Epiphytes differ from parasites in that epiphytes grow on other plants for physical support and do not negatively affect the host. An epiphytic organism, not a plant is sometimes called an epibiont. Epiphytes are found in the temperate zone or in the tropics. Epiphyte species make good houseplants due to their minimal soil requirements. Epiphytes provide a rich and diverse habitat for other organisms including animals, fungi and myxomycetes. Epiphyte is one of the subdivisions of the Raunkiær system; the term epiphytic derives from the Greek epi- and phyton. Epiphytic plants are sometimes called "air plants".
However, there are many aquatic species of algae. The best-known epiphytic plants include mosses and bromeliads such as Spanish moss, but epiphytes may be found in every major group of the plant kingdom. 89% of terrestrial epiphyte species are flowering plants. The second largest group are the leptosporangiate ferns, with about 2800 species. In fact, about one third of all ferns are epiphytes; the third largest group is clubmosses, with 190 species, followed by a handful of species in each of the spikemosses, other ferns and cycads. The first important monograph on epiphytic plant ecology was written by A. F. W. Schimper. Assemblages of large epiphytes occur most abundantly in moist tropical forests, but mosses and lichens occur as epiphytes in all biomes. In Europe there are no dedicated epiphytic plants using roots, but rich assemblages of mosses and lichens grow on trees in damp areas, the common polypody fern grows epiphytically along branches. Grass, small bushes or small trees may grow in suspended soils up trees.
Epiphytes however, can be categorized into holo-epiphytes or hemi-epiphytes. A holo-epiphyte is a plant that spends its whole life cycle without contact with the ground and a hemi-epiphyte is a plant that spends only half of its life without the ground before the roots can reach or make contact with the ground. Orchids are a common example of holo-epiphytes and Strangler Figs are an example of hemi-epiphytes. Epiphytes are not connected to the soil, must get nutrients from other sources, such as fog, dew and mist, or from nutrients being released from the ground rooted plants by decomposition or leaching, dinitrogen fixation. Epiphytic plants attached to their hosts high in the canopy have an advantage over herbs restricted to the ground where there is less light and herbivores may be more active. Epiphytic plants are important to certain animals that may live in their water reservoirs, such as some types of frogs and arthropods. Epiphytes can have a significant effect on the microenvironment of their host, of ecosystems where they are abundant, as they hold water in the canopy and decrease water input to the soil.
Some non-vascular epiphytes such as lichens and mosses are well known for their ability to take up water rapidly. The epiphytes create a cooler and moister environment in the host plant canopy greatly reducing water loss by the host through transpiration; the ecology of epiphytes in marine environments differs from those in terrestrial ecosystems. Epiphytes in marine systems are species of algae, fungi, bryozoans, protozoa, crustaceans and any other sessile organism that grows on the surface of a plant seagrasses or algae. Settlement of epiphytic species is influenced by a number of factors including light, currents and trophic interactions. Algae are the most common group of epiphytes in marine systems. Photosynthetic epiphytes account for a large amount of the photosynthesis in systems in which they occur; this is between 20 and 60% of the total primary production of the ecosystem. They are a general group of organisms and are diverse, providing food for a great number of fauna. Snail and nudibranch species are two common grazers of epiphytes.
Epiphyte species composition and the amount of epiphytes can be indicative of changes in the environment. Recent increases in epiphyte abundance have been linked to excessive nitrogen put into the environment from farm runoff and storm water. High abundance of epiphytes are considered detrimental to the plants that they grow on causing damage or death in seagrasses; this is. Epiphytes in marine systems are known to grow with fast generation times. Epiphyllum - a genus of epiphytic cacti Parasitic plant Epilith, an organism that grows in a rock Epibiont, an organism that grows on another life form Epiphytic bacteria Epiphytic fungus Epiphytes on a Scot's Pine in Gorbie Glen, Scotland
Brassica
Brassica is a genus of plants in the mustard family. The members of the genus are informally known as cruciferous vegetables, cabbages, or mustard plants. Crops from this genus are sometimes called cole crops—derived from the Latin caulis, denoting the stem or stalk of a plant; the genus Brassica is known for its important agricultural and horticultural crops and includes a number of weeds, both of wild taxa and escapees from cultivation. Brassica species and varieties used for food include broccoli, cabbage, choy sum, rutabaga and some seeds used in the production of canola oil and the condiment mustard. Over 30 wild species and hybrids are in cultivation, plus numerous cultivars and hybrids of cultivated origin. Most are seasonal plants. Brassica plants have been the subject of much scientific interest for their agricultural importance. Six particular species evolved by the combining of chromosomes from three earlier species, as described by the Triangle of U theory; the genus is native to the Mediterranean and temperate regions of Asia.
Many wild species grow as weeds in North America, South America, Australia. A dislike for cabbage or broccoli can result from the fact that these plants contain a compound similar to phenylthiocarbamide, either bitter or tasteless to people depending on their taste buds. All parts of some species or other have been developed for food, including the root, leaves, flowers and seeds; some forms with white or purple foliage or flowerheads are sometimes grown for ornament. Brassica species are sometimes used as food plants by the larvae of a number of Lepidoptera species—see List of Lepidoptera that feed on Brassica. Brassica vegetables are regarded for their nutritional value, they provide high amounts of vitamin C and soluble fiber and contain nutrients with anticancer properties: 3,3'-diindolylmethane and selenium. Boiling reduces the level of anticancer compounds, but steaming and stir frying do not result in significant loss. Steaming these vegetable for three to four minutes is recommended to maximize sulforaphane.
Brassica vegetables are rich in indole-3-carbinol, a chemical which boosts DNA repair in cells in vitro and appears to block the growth of cancer cells in vitro. They are a good source of carotenoids, with broccoli having high levels. Researchers at the University of California at Berkeley have discovered that 3,3'-diindolylmethane in Brassica vegetables is a potent modulator of the innate immune response system with potent antiviral and anticancer activity. However, it is an antiandrogen but is known to be antiandrogenic only in hormone-sensitive prostate cancer cells; these vegetables contain goitrogens, some of which suppress thyroid function. Goitrogens can induce goiter in the absence of normal iodine intake. There is some disagreement among botanists on the classification and status of Brassica species and subspecies; the following is an abbreviated list, with an emphasis on economically important species. B. balearica: Mallorca cabbage B. carinata: Abyssinian mustard or Abyssinian cabbage, used to produce biodiesel B. elongata: elongated mustard B. fruticulosa: Mediterranean cabbage B. hilarionis: St Hilarion cabbage B. juncea: Indian mustard and leaf mustards, Sarepta mustard B. napus: rapeseed, rutabaga, Siberian kale B. narinosa: broadbeaked mustard B. nigra: black mustard B. oleracea: kale, collard greens, cauliflower, kai-lan, Brussels sprouts, kohlrabi B. perviridis: tender green, mustard spinach B. rapa: Chinese cabbage, rapini, komatsuna B. rupestris: brown mustard B. tournefortii: Asian mustard B. alba or B. hirta —see Sinapis alba B. geniculata —see Hirschfeldia incana B. kaber —see Sinapis arvensis Bayer CropScience announced it had sequenced the entire genome of rapeseed and its constituent genomes present in B. rapa and B. oleracea in 2009.
The B. rapa genome was sequenced by the Multinational Brassica Genome Project in 2011. This represents the A genome component of the amphidiploid crop species B. napus and B. juncea. ‘Brassica’ is Pliny's name for several cabbage-like plants. Media related to Brassica at Wikimedia Commons Data related to Brassica at Wikispecies
Plant ecology
Plant ecology is a subdiscipline of ecology which studies the distribution and abundance of plants, the effects of environmental factors upon the abundance of plants, the interactions among 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, 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, Mediterranean ecosystems, temperate forest ecosystems, temperate grasslands, coniferous forests, 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. One feature that defines plants is photosynthesis.
Photosynthesis is the process of a chemical reactions to create glucose and oxgyen, vital for plant life. One of the most important aspects of plant ecology is the role plants have played in creating the oxygenated atmosphere of earth, an event that occurred some 2 billion years ago, it can be dated by the deposition of banded iron formations, distinctive sedimentary rocks with large amounts of iron oxide. At the same time, plants began removing carbon dioxide from the atmosphere, thereby initiating the process of controlling Earth's climate. A long term trend of the Earth has been toward increasing oxygen and decreasing carbon dioxide, many other events in the Earth's history, like the first movement of life onto land, are tied to this sequence of events. One of the early classic books on plant ecology was written by J. E. Weaver and F. E. Clements, it talks broadly about plant communities, the importance of forces like competition and processes like succession. Plant ecology can be divided by levels of organization including plant ecophysiology, plant population ecology, community ecology, ecosystem ecology, landscape ecology and biosphere ecology.
The study of plants and vegetation is complicated by their form. First, most plants are rooted in the soil, which makes it difficult to observe and measure nutrient uptake and species interactions. Second, plants reproduce vegetatively, asexually, in a way that makes it difficult to distinguish individual plants. Indeed, the concept of an individual is doubtful, since a tree may be regarded as a large collection of linked meristems. Hence, plant ecology and animal ecology have different styles of approach to problems that involve processes like reproduction and mutualism; some plant ecologists have placed considerable emphasis upon trying to treat plant populations as if they were animal populations, focusing on population ecology. Many other ecologists believe that while it is useful to draw upon population ecology to solve certain scientific problems, plants demand that ecologists work with multiple perspectives, appropriate to the problem, the scale and the situation. Plant ecology has its origin in the application of plant physiology to the questions raised by plant geographers.
Carl Ludwig Willdenow was one of the first to note that similar climates produced similar types of vegetation when they were located in different parts of the world. Willdenow's student, Alexander von Humboldt, used physiognomy to describe vegetation types and observed that the distribution vegetation types was based on environmental factors. Plant geographers who built upon Humboldt's work included Joakim Frederik Schouw, A. P. de Candolle, August Grisebach and Anton Kerner von Marilaun. Schouw's work, published in 1822, linked plant distributions to environmental factors and established the practice of naming plant associations by adding the suffix -etum to the name of the dominant species. Working from herbarium collections, De Candolle searched for general rules of plant distribution and settled on using temperature as well. Grisebach's two-volume work, Die Vegetation der Erde nach Ihrer Klimatischen Anordnung, published in 1872, saw plant geography reach its "ultimate form" as a descriptive field.
Starting in the 1870s, Swiss botanist Simon Schwendener, together with his students and colleagues, established the link between plant morphology and physiological adaptations, laying the groundwork for the first ecology textbooks, Eugenius Warming's Plantesamfund and Andreas Schimper's 1898 Pflanzengeographie auf Physiologischer Grundlage. Warming incorporated plant morphology, physiology taxonomy and biogeography into plant geography to create the field of plant ecology. Although more morphological than physiological, Schimper's has been considered the beginning of plant physiological ecology. Plant ecology was built around static ideas of plant distribution. Henry Chandler Cowles' studies of plant succession on the Lake Michigan sand dunes and Frederic Clements' 1916 monograph on the subject established it as a key element of plant ecology. Plant ecology developed within the wider discipline of ecology over the twentieth century. Inspired by Warming's Plantesamfund, Arthur Tansley set out to map British plant communities.
In 1904 he teamed up with William Gardner Smith and others involved in vegetation mapping to establish the Central Committee for the Survey and Study of British Vegetation shortened to British Vegetation Committee. In 1913, the British Vegetation Committee organised the British Ecological
Orchidaceae
The Orchidaceae are a diverse and widespread family of flowering plants, with blooms that are colourful and fragrant known as the orchid family. Along with the Asteraceae, they are one of the two largest families of flowering plants; the Orchidaceae have about 28,000 accepted species, distributed in about 763 genera. The determination of which family is larger is still under debate, because verified data on the members of such enormous families are continually in flux. Regardless, the number of orchid species nearly equals the number of bony fishes and is more than twice the number of bird species, about four times the number of mammal species; the family encompasses about 6–11% of all seed plants. The largest genera are Bulbophyllum, Epidendrum and Pleurothallis, it includes Vanilla–the genus of the vanilla plant, the type genus Orchis, many cultivated plants such as Phalaenopsis and Cattleya. Moreover, since the introduction of tropical species into cultivation in the 19th century, horticulturists have produced more than 100,000 hybrids and cultivars.
Orchids are distinguished from other plants, as they share some evident, shared derived characteristics, or synapomorphies. Among these are: bilateral symmetry of the flower, many resupinate flowers, a nearly always modified petal, fused stamens and carpels, small seeds. All orchids are perennial herbs, they can grow according to two patterns: Monopodial: The stem grows from a single bud, leaves are added from the apex each year and the stem grows longer accordingly. The stem of orchids with a monopodial growth can reach several metres in length, as in Vanda and Vanilla. Sympodial: Sympodial orchids have a front and a back; the plant produces a series of adjacent shoots, which grow to a certain size and stop growing and are replaced. Sympodial orchids grow laterally following the surface of their support; the growth continues by development of new leads, with their own leaves and roots, sprouting from or next to those of the previous year, as in Cattleya. While a new lead is developing, the rhizome may start its growth again from a so-called'eye', an undeveloped bud, thereby branching.
Sympodial orchids may have visible pseudobulbs joined by a rhizome, which creeps along the top or just beneath the soil. Terrestrial orchids may form corms or tubers; the root caps of terrestrial orchids are white. Some sympodial terrestrial orchids, such as Orchis and Ophrys, have two subterranean tuberous roots. One is used as a food reserve for wintry periods, provides for the development of the other one, from which visible growth develops. In warm and humid climates, many terrestrial orchids do not need pseudobulbs. Epiphytic orchids, those that grow upon a support, have modified aerial roots that can sometimes be a few meters long. In the older parts of the roots, a modified spongy epidermis, called velamen, has the function of absorbing humidity, it can have a silvery-grey, white or brown appearance. In some orchids, the velamen includes spongy and fibrous bodies near the passage cells, called tilosomes; the cells of the root epidermis grow at a right angle to the axis of the root to allow them to get a firm grasp on their support.
Nutrients for epiphytic orchids come from mineral dust, organic detritus, animal droppings and other substances collecting among on their supporting surfaces. The base of the stem of sympodial epiphytes, or in some species the entire stem, may be thickened to form a pseudobulb that contains nutrients and water for drier periods; the pseudobulb has a smooth surface with lengthwise grooves, can have different shapes conical or oblong. Its size is variable; some Dendrobium species have long, canelike pseudobulbs with short, rounded leaves over the whole length. With ageing, the pseudobulb becomes dormant. At this stage, it is called a backbulb. Backbulbs still hold nutrition for the plant, but a pseudobulb takes over, exploiting the last reserves accumulated in the backbulb, which dies off, too. A pseudobulb lives for about five years. Orchids without noticeable pseudobulbs are said to have growths, an individual component of a sympodial plant. Like most monocots, orchids have simple leaves with parallel veins, although some Vanilloideae have reticulate venation.
Leaves may be ovate, lanceolate, or orbiculate, variable in size on the individual plant. Their characteristics are diagnostic, they are alternate on the stem folded lengthwise along the centre, have no stipules. Orchid leaves have siliceous bodies called stegmata in the vascular bundle sheaths and are fibrous; the structure of the leaves corresponds to the specific habitat of the plant. Species that bask in sunlight, or grow on sites which can be very dry, have thick, leathery leaves and the laminae are covered by a waxy cuticle to retain their necessary water supply. Shade-loving species, on the other hand, have thin leaves; the leaves of most orchids are perennial, that is, they live for several years, while others those with plicate leaves as in Catasetum, shed them annually and de
Cyperaceae
The Cyperaceae are a family of graminoid, monocotyledonous flowering plants known as sedges, which superficially resemble the related rushes and the more distantly related grasses. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus Carex with over 2,000 species; these species are distributed, with the centers of diversity for the group occurring in tropical Asia and tropical South America. While sedges may be found growing in all environments, many are associated with wetlands, or with poor soils. Ecological communities dominated by sedges are known as sedgelands. Features distinguishing members of the sedge family from grasses or rushes are stems with triangular cross-sections and leaves that are spirally arranged in three ranks; some well-known sedges include the water chestnut and the papyrus sedge, from which the writing material papyrus was made. This family includes cotton-grass, spike-rush, nutsedge or nutgrass, white star sedge.
Cyperaceae at The Plant List Cyperaceae at The Families of Flowering Plants Cyperaceae at the Encyclopedia of Life Cyperaceae at the Angiosperm Phylogeny Website Cyperaceae at the Royal Botanic Gardens, Kew Cyperaceae at the online Flora of North America Cyperaceae at the online Flora of Michigan Cyperaceae at the online Flora of Northern Ireland Cyperaceae at the online Flora of Zimbabwe Cyperaceae at the online Flora of Western Australia Cyperaceae at the online Flora of New South Wales Cyperaceae at the online Flora of New Zealand Cyperaceae at Flowers in Israel
Xeronema callistemon
Xeronema callistemon is a species of flowering plant endemic to the Poor Knights Islands and Taranga Island in the north of New Zealand. It has a common name Poor Knights lily; the plant is listed as vulnerable in the 1997 IUCN Red List of Plants, but as of October 2010 is not listed in the IUCN Red List of Threatened Species. The common name of the plant originates from the Poor Knights Islands; the islands, in turn, were so named because of their similarity in shape to the Poor Knights Pudding – a bread-based dish popular at the time of their discovery by Europeans. The botanical species name means "with a beautiful stamen", referring to the prominent red stamens of the plant's flowers; the green stalks of Xeronema callistemon start growing vertically sheathed by overlapping leaves. As the flower emerges, the stalk turn sideways, growing a red flower raceme with prominent red stamens tipped with orange pollen and resembles a giant bottlebrush or toothbrush; the individual flower tepals are 10–15 mm long, the stamens up to 4 centimetres tall, the length of the brush is between 18 and 25 cm and can reach 45 cm.
The plant itself is about 1 m tall and 1–4 m wide. Xeronema callistemon grows on rhyolite sea cliffs and rocky outcrops and sometimes in forest, it is pollinated by birds and butterflies. If its seed falls on a nearby tree, such as Metrosideros excelsa it may grow as an epiphyte on it; the species has no obvious natural enemies and is listed as vulnerable because it grows only on two islands. These islands are protected by the New Zealand Government as nature reserves and have a limited access. However, the plant is becoming popular for cultivation in private gardens. A related species, Xeronema moorei, is found on the islands of New Caledonia, 1500 km to the northwest. Plants grow from fresh falling seeds. Although they germinate it might take 10–15 years for them to grow into the flowering size, they flower between September and December, peaking in October
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