Semelparity and iteroparity
Semelparity and iteroparity are two classes of possible reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime; some botanists use the parallel terms polycarpy. In semelparous species, death after reproduction is part of an overall strategy that includes putting all available resources into maximizing reproduction, at the expense of future life. In any iteroparous population there will be some individuals who die between their first and second reproductive episodes, but unless this is part of a syndrome of programmed death after reproduction, this would not be called semelparity; this distinction is related to the difference between annual and perennial plants. An annual is a plant that completes its life cycle in a single season, is semelparous. Perennials live for more than one season and are iteroparous.
Semelparity and iteroparity are not speaking, alternative strategies, but extremes along a continuum of possible modes of reproduction. Many organisms considered to be semelparous can, under certain conditions, separate their single bout of reproduction into two or more episodes; the word semelparity was coined by evolutionary biologist Lamont Cole, comes from the Latin semel'once, a single time' and pario'to beget'. This differs from iteroparity in that iteroparous species are able to have multiple reproductive cycles and therefore can mate more than once in their lifetime. Semelparity is known as "big bang" reproduction, since the single reproductive event of semelparous organisms is large as well as fatal. A classic example of a semelparous organism is Pacific salmon, which lives for many years in the ocean before swimming to the freshwater stream of its birth and dying. Other semelparous animals include many insects, including some species of butterflies and mayflies, many arachnids, some molluscs such as some species of squid and octopus.
Semelparity occurs in smelt and capelin, but is rare in vertebrates other than bony fish. In amphibians, it is known only among some Hyla frogs including the gladiator frog. Annual plants, including all grain crops and most domestic vegetables, are semelparous. Long-lived semelparous plants include century plant, Lobelia telekii, some species of bamboo; this form of lifestyle is consistent with r-selected strategies as many offspring are produced and there is low parental input, as one or both parents die after mating. All of the male’s energy is diverting into mating and the immune system is repressed. High levels of corticosteroids are sustained over long periods of time; this triggers immune and inflammatory system failure and gastrointestinal hemorrhage, which leads to death. The term iteroparity comes from the Latin itero, to repeat, pario, to beget. An example of an iteroparous organism is a human—humans are biologically capable of having offspring many times over the course of their lives.
Iteroparous vertebrates include all birds, most reptiles all mammals, most fish. Among invertebrates, most mollusca and many insects are iteroparous. Most perennial plants are iteroparous, it is a biological precept that within its lifetime an organism has a limited amount of energy/resources available to it, must always partition it among various functions such as collecting food and finding a mate. Of relevance here is the trade-off between fecundity and survivorship in its life history strategy; these trade-offs come into play in the evolution of semelparity. It has been demonstrated that semelparous species produce more offspring in their single fatal reproductive episode than do related iteroparous species in any one of theirs. However, the opportunity to reproduce more than once in a lifetime, with greater care for the development of offspring produced, can offset this numerical benefit. One class of models that tries to explain the differential evolution of semelparity and iteroparity examines the shape of the trade-off between offspring produced and offspring forgone.
In economic terms, offspring produced is equivalent to a benefit function, while offspring forgone is comparable to a cost function. The reproductive effort of an organism—the proportion of energy that it puts into reproducing, as opposed to growth or survivorship—occurs at the point where the distance between offspring produced and offspring forgone is the greatest; the accompanying graph shows the offspring-produced and offspring-forgone curves for an iteroparous organism: In the first graph, the marginal cost of offspring produced is decreasing and the marginal cost of offspring forgone is increasing. In this situation, the organism only devotes a portion of its resources to reproduction, uses the rest of its resources on growth and survivorship so that it can reproduce again in the future. However, it is possible for the marginal cost of offspring produced to increase, for the marginal cost of offspring forgone to decrease; when this is the case, it is favorable for the organism to reproduce a single time.
The organism devotes all of its resources to that one episode of reproduction, so it
The Arecaceae are a botanical family of perennial plants. Their growth form can be climbers, shrubs and stemless plants, all known as palms; those having a tree form are colloquially called palm trees. They are flowering a family in the monocot order Arecales. 181 genera with around 2600 species are known, most of them restricted to tropical and subtropical climates. Most palms are distinguished by their large, evergreen leaves, known as fronds, arranged at the top of an unbranched stem. However, palms exhibit an enormous diversity in physical characteristics and inhabit nearly every type of habitat within their range, from rainforests to deserts. Palms are among the most extensively cultivated plant families, they have been important to humans throughout much of history. Many common products and foods are derived from palms. In contemporary times, palms are widely used in landscaping, making them one of the most economically important plants. In many historical cultures, because of their importance as food, palms were symbols for such ideas as victory and fertility.
For inhabitants of cooler climates today, palms symbolize the vacations. Whether as shrubs, trees, or vines, palms have two methods of growth: solitary or clustered; the common representation is that of a solitary shoot ending in a crown of leaves. This monopodial character may be exhibited by prostrate and trunk-forming members; some common palms restricted to solitary growth include Roystonea. Palms may instead grow in sparse though dense clusters; the trunk develops an axillary bud at a leaf node near the base, from which a new shoot emerges. The new shoot, in turn, produces a clustering habit results. Sympodial genera include many of the rattans and Rhapis. Several palm genera have both solitary and clustering members. Palms which are solitary may grow in clusters and vice versa; these aberrations suggest. Palms have large, evergreen leaves that are either palmately or pinnately compound and spirally arranged at the top of the stem; the leaves have a tubular sheath at the base that splits open on one side at maturity.
The inflorescence is a spadix or spike surrounded by one or more bracts or spathes that become woody at maturity. The flowers are small and white, radially symmetric, can be either uni- or bisexual; the sepals and petals number three each, may be distinct or joined at the base. The stamens number six, with filaments that may be separate, attached to each other, or attached to the pistil at the base; the fruit is a single-seeded drupe but some genera may contain two or more seeds in each fruit. Like all monocots, palms do not have the ability to increase the width of a stem via the same kind of vascular cambium found in non-monocot woody plants; this explains the cylindrical shape of the trunk, seen in palms, unlike in ring-forming trees. However, many palms, like some other monocots, do have secondary growth, although because it does not arise from a single vascular cambium producing xylem inwards and phloem outwards, it is called "anomalous secondary growth"; the Arecaceae are notable among monocots for their height and for the size of their seeds and inflorescences.
Ceroxylon quindiuense, Colombia's national tree, is the tallest monocot in the world, reaching up to 60 m tall. The coco de mer has the largest seeds of 40 -- 50 cm in diameter and weighing 15 -- 30 kg each. Raffia palms have the largest leaves of any plant, up to 25 m long and 3 m wide; the Corypha species have the largest inflorescence of any plant, up to 7.5 m tall and containing millions of small flowers. Calamus stems. Most palms are native to subtropical climates. Palms can be found in a variety of different habitats, their diversity is highest in lowland forests. South America, the Caribbean, areas of the south Pacific and southern Asia are regions of concentration. Colombia may have the highest number of palm species in one country. There are some palms that are native to desert areas such as the Arabian peninsula and parts of northwestern Mexico. Only about 130 palm species grow beyond the tropics in humid lowland subtropical climates, in highlands in southern Asia, along the rim lands of the Mediterranean Sea.
The northernmost native palm is Chamaerops humilis, which reaches 44°N latitude along the coast of southern France. In the southern hemisphere, the southernmost palm is the Rhopalostylis sapida, which reaches 44°S on the Chatham Islands where an oceanic climate prevails. Cultivation of palms is possible north of subtropical climates, some higher latitude locals such as Ireland, Scotland and the Pacific Northwest feature a few palms in protected locations. Palms inhabit a variety of ecosystems. More than two-thirds of palm species live in humid moist forests, where some species grow tall enough to form part of the canopy and shorter ones form part of the understory; some species form pure stands in areas with poor drainage or regular flooding, including Raphia hookeri, common in coastal freshwater swamps in West Africa. Other palms live in tropical mountain habitats above 1000 m, such as those in the genus Ceroxylon native to the Andes. Palms may live in grasslands and scrublands associated with a water source, in desert oases such as the date palm.
A few palms are adapted to basic lime soils, while others are ada
Alphonse Pyramus de Candolle
Alphonse Louis Pierre Pyrame de Candolle was a French-Swiss botanist, the son of the Swiss botanist Augustin Pyramus de Candolle. De Candolle first devoted himself to the study of law, but drifted to botany and succeeded to his father's chair at the University of Geneva, he published a number of botanical works, including continuations of the Prodromus in collaboration with his son, Anne Casimir Pyrame de Candolle. Among his other contributions is the formulation, based on his father's work for the Prodromus, of the first Laws of Botanical Nomenclature, adopted by the International Botanical Congress in 1867, was the prototype of the current ICN, he was elected a foreign member of the Royal Swedish Academy of Sciences in 1859 and was awarded the Linnean Medal of the Linnean Society of London in 1889. He was elected a foreign member of the Royal Netherlands Academy of Arts and Sciences in 1878, he is known for a study of the religious affiliations of foreign members of the French and British Academies of Science during the Scientific Revolution that demonstrated that in both academies Protestants were more represented than Catholics by comparison with catchment populations.
This observation continues to be used as a demonstration that Protestants were more inclined to be scientifically active during the Scientific Revolution than Roman Catholics. In 1855 de Candolle published Géographie botanique raisonnée This was a ground-breaking book that for the first time brought together the large mass of data being collected by the expeditions of the time; the natural sciences had become specialized yet this book synthesized them to explain living organisms within their environment and why plants were distributed the way they were, all upon a geologic scale. This book had a significant impact upon Harvard botanist Asa Gray. de Candolle, Alphonse. Géographie botanique raisonnée. Paris: V. Masson. Candolle, Alphonse de - Lois de la nomenclature botanique adoptées par le Congrès international de botanique tenu à Paris en août 1867... Genève et Bale: H. Georg. Baillière et fils, 1867. 64 p. Candolle, Alphonse de - Histoire des Sciences et des Savants depuis deux Siècles. Geneva, 1873.
Candolle, Alphonse de.. Darwin considéré au point de vue des causes. Genève: H. Georg. de Candolle, Alphonse. Origin of Cultivated Plants. New York: Appleton. Retrieved 19 February 2015. Fancher, R E. "Alphonse de Candolle, Francis Galton, the early history of the nature-nurture controversy". Journal of the History of the Behavioral Sciences. 19: 341–52. Doi:10.1002/1520-669619:4<341::aid-jhbs2300190403>3.0.co. PMID 11608560. de Morsier, G.. "". Gesnerus. 29: 129–60. PMID 4570878. Works available at Botanicus
Strobilanthes is a genus of about 350 species of flowering plants in the family Acanthaceae native to tropical Asia and Madagascar, but with a few species extending north into temperate regions of Asia. Many species are cultivated for their two-lipped, hooded flowers in shades of blue, pink and purple. Most require protection in frost-prone areas. Strobilanthes atropurpurea is a temperate species, native to eastern Siberia. Strobilanthes dyeriana is a tropical plant native to Myanmar, it is grown for its dark green foliage with bright, metallic-purple stripes radiating outward from the central leaf vein. In proper conditions, it will produce pale purple flowers. Persian Shield grows best outdoors in USDA zones 9 and 10, although it can survive in other zones as a houseplant given sufficient temperature, soil moisture and humidity, it has gained the Royal Horticultural Society's Award of Garden Merit. Strobilanthes species are used as food plants by the larvae of some Lepidoptera species including Endoclita malabaracus, recorded on S. callosus.
There is a database conflict about the status of Pachystrobilus involucratus, with the Catalogue of Life placing the species in this genus. EFloras search results: Strobilanthes Data related to Strobilanthes at Wikispecies Media related to Strobilanthes at Wikimedia Commons
Argyroxiphium is a small genus of plants in the sunflower family, Asteraceae. Its members are known by the common names of silversword or greensword due to their long, narrow leaves and the silvery hairs on some species, it belongs to a larger radiation of over 50 species, including the physically different genera Dubautia and Wilkesia. This grouping is referred to as the silversword alliance; these perennials are endemic to Hawaiʻi, occurring only on the islands of Maui and Hawaiʻi in an localized distribution. They are found above 1,500 m in elevation in alpine deserts or bogs, indicating an adaptation to low-nutrient soils; the Kaʻū or Mauna Loa silversword is the most adaptable: it can be found in rocky lava flows and open forest. They consist of rosette-forming epigeal dwarf shrubs, they may consist of a short-branched rosette, or spreading with runners. The flower heads consist of a ring of pistillate ray florets around 30 to 600 disk florets; the corolla varies in color from purplish to wine yellow, while the anthers are dark.
A rosette will grow from 5 -- 20 years before flowering. For those with a single rosette, this means the death of the plant; because they require cross-pollination by insects, many plants must flower at the same time in close proximity or they will fail to set seed. A significant population must exist for enough to flower each year for pollination to occur. Despite appearances, they are closely related to the genus Dubautia. Although some Dubautia are radically different from silverswords, those found in wet forests and alpine deserts grade into the form of silverswords. Hybrids between Argyroxiphium sandwicense and Dubautia menziesii are common in Haleakalā Crater. Although the two species are quite distinct, the hybrids span the entire range of variation between them. Silverswords and greenswords are sensitive to disturbance, their shallow root systems are crushed in the boggy soil or loose volcanic cinders they grow in. The succulent leaves are eaten by goats in the dry summits, pigs disturb the fragile bog vegetation.
All species are restricted in range, those that are protected are vulnerable to catastrophic events. The East Maui greensword is extinct, but in 1989 plants were discovered that appear to be hybrids between it and the Haleakalā Silversword; the Mauna Kea and Mauna Loa silverswords both have small populations, but are being cultivated and outplanted in protected areas. The largest population of Mauna Loa silverswords is in Kahuku, acquired by Hawaii Volcanoes National Park. Accepted speciesArgyroxiphium caliginis C. N. Forbes – ʻEke silversword Argyroxiphium grayanum O. Deg. – greensword Argyroxiphium × kai D. D. Keck Argyroxiphium kauense O. Deg. & I. Deg. – Mauna Loa or Kaʻū silversword Argyroxiphium sandwicense DC. – silversword Argyroxiphium sandwicense ssp. sandwicense DC. – Mauna Kea silversword Argyroxiphium sandwicense ssp. macrocephalum Meyrat – Haleakalā silversword Argyroxiphium virescens Hillebr. – East Maui greensword includednow in Dubautia A. gymnoxiphium - Dubautia gymnoxiphium Kaʻahele Hawaiʻi Native Plants Hawaiian silversword alliance, University of Hawii Botany US Department of Agriculture plants profile
Tachigali is a flowering plant genus in the legume family that contains 54 species. Species include: Tachigali multijuga Benth. Tachigali myrmecophila Tachigali paniculata Aubl. – Carvoeiro Tachigali paraensis Barneby Tachigali tessmannii Tachigali versicolor Standl. & L. O. Williams – "suicide tree" Van Der Werff, H.. "A Synopsis of the Genus Tachigali in Northern South America1". Annals of the Missouri Botanical Garden. 95: 618–661. Doi:10.3417/2007159
Poaceae or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses referred to collectively as grass. Poaceae includes the cereal grasses and the grasses of natural grassland and cultivated lawns and pasture. Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks; the lower part of each leaf encloses the stem. With around 780 genera and around 12,000 species, Poaceae are the fifth-largest plant family, following the Asteraceae, Orchidaceae and Rubiaceae. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica. Grasses are an important part of the vegetation in many other habitats, including wetlands and tundra; the Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize, rice and millet as well as forage, building materials and fuel.
Though they are called "grasses", seagrasses and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales; the name Poaceae was given by John Hendley Barnhart in 1895, based on the tribe Poeae described in 1814 by Robert Brown, the type genus Poa described in 1753 by Carl Linnaeus. The term is derived from the Ancient Greek πόα. Grasses include some of the most versatile plant life-forms, they became widespread toward the end of the Cretaceous period, fossilized dinosaur dung have been found containing phytoliths of a variety that include grasses that are related to modern rice and bamboo. Grasses have adapted to conditions in lush rain forests, dry deserts, cold mountains and intertidal habitats, are the most widespread plant type. A cladogram shows subfamilies and approximate species numbers in brackets: Before 2005, fossil findings indicated that grasses evolved around 55 million years ago.
Recent findings of grass-like phytoliths in Cretaceous dinosaur coprolites have pushed this date back to 66 million years ago. In 2011, revised dating of the origins of the rice tribe Oryzeae suggested a date as early as 107 to 129 Mya. Wu, You & Li described grass microfossils extracted from a specimen of the hadrosauroid dinosaur Equijubus normani from the Early Cretaceous Zhonggou Formation; the authors noted that India became separated from Antarctica, therefore all other continents at the beginning of late Aptian, so the presence of grasses in both India and China during the Cretaceous indicates that the ancestor of Indian grasses must have existed before late Aptian. Wu, You & Li considered the Barremian origin for grasses to be probableThe relationships among the three subfamilies Bambusoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more related to each other than to Oryzoideae; this separation occurred within the short time span of about 4 million years.
According to Lester Charles King the spread of grasses in the Late Cenozoic would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a free face were common. King argued that this was the result of more acting surface wash caused by carpets of grass which in turn would have resulted in more soil creep. Grasses may be annual or perennial herbs with the following characteristics: The stems of grasses, called culms, are cylindrical and are hollow, plugged at the nodes, where the leaves are attached. Grass leaves are nearly always alternate and distichous, have parallel veins; each leaf is differentiated into a lower sheath hugging a blade with entire margins. The leaf blades of many grasses are hardened with silica phytoliths, which discourage grazing animals. A membranous appendage or fringe of hairs called the ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath. Flowers of Poaceae are characteristically arranged in each having one or more florets.
The spikelets are further grouped into spikes. The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two bracts at called glumes, followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea; the flowers are hermaphroditic—maize being an important exception—and anemophilous or wind-pollinated, although insects play a role. The perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea; this complex structure can be seen in the image on the right. The fruit of grasses is a caryopsis. A tiller is a leafy shoot other than the first shoot produced from the seed. Grass blades grow at the base of the blade and not from elongated stem tips; this low growth point evolved in response to grazing animals and allows grasses to be grazed or mown without severe damage to the plant. Three general classifications of growth habit present in g