Purshia is a small genus of 5-8 species of flowering plants in the family Rosaceae, native to western North America, where they grow in dry climates from southeast British Columbia in Canada south throughout the western United States to northern Mexico. The classification of Purshia within the Rosaceae has been unclear; the genus was placed in the subfamily Rosoideae, but is now placed in subfamily Dryadoideae. They are deciduous or evergreen shrubs reaching 0.3–5 m tall. The leaves are small, 1–3 cm long three- to five-lobed, with revolute margins; the flowers are 1 -- 2 cm diameter, with five yellow stamens. The fruit is a cluster of dry, leathery achenes 2–6 cm long; the roots have root nodules. The evergreen species were treated separately in the genus Cowania in the past. Purshia ericifolia — Heath cliffrose. Texas. Purshia glandulosa — Desert bitterbrush. Nevada, Arizona. Purshia mexicana — Mexican cliffrose. Mexico, Arizona. Purshia pinkavae — Pinkava's cliffrose. Arizona. Purshia plicata — Antelope bush.
Mexico. Purshia stansburyana — Stansbury cliffrose. Idaho south to California and New Mexico. Purshia subintegra. Arizona. Purshia tridentata — Antelope bitterbrush. British Columbia south to California and New Mexico. Jepson Flora Project: Purshia — Media related to Purshia at Wikimedia Commons
The rose subfamily Rosoideae consists of more than 850 species, including many shrubs, perennial herbs, fruit plants such as strawberries and brambles. Only a few are annual herbs; the circumscription of the Rosoideae is still not wholly certain.
Nitrogen fixation is a process by which nitrogen in the air is converted into ammonia or related nitrogenous compounds. Atmospheric nitrogen, is molecular dinitrogen, a nonreactive molecule, metabolically useless to all but a few microorganisms. Biological nitrogen fixation converts N2 into ammonia, metabolized by most organisms. Nitrogen fixation is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins, nucleoside triphosphates and nucleic acids; as part of the nitrogen cycle, it is essential for the manufacture of fertilizer. It is indirectly, relevant to the manufacture of all chemical compounds that contain nitrogen, which includes explosives, most pharmaceuticals, dyes. Nitrogen fixation is carried out in the soil by a wide range of microorganisms termed diazotrophs that include bacteria such as Azotobacter, archaea; some nitrogen-fixing bacteria have symbiotic relationships with some plant groups legumes.
Looser non-symbiotic relationships between diazotrophs and plants are referred to as associative, as seen in nitrogen fixation on rice roots. Nitrogen fixation occurs between some termites and fungi, it occurs in the air by means of NOx production by lightning. All biological nitrogen fixation is effected by enzymes called nitrogenases; these enzymes contain iron with a second metal molybdenum but sometimes vanadium. Nitrogen can be fixed by lightning converting nitrogen and oxygen into NO x. NO x may react with water to make nitrous acid or nitric acid, which seeps into the soil, where it makes nitrate, of use to growing plants. Nitrogen in the atmosphere is stable and nonreactive due to there being a triple bond between atoms in the N2 molecule. Lightning produces enough energy and heat to break this bond allowing the nitrogen atoms to react with oxygen forming NOx; this itself cannot be used by plants, but as this molecule cools it reacts with more oxygen to form NO2. This molecule in turn reacts with water to produce HNO3, usable by plants.
Biological nitrogen fixation was discovered by the German agronomist Hermann Hellriegel and Dutch microbiologist Martinus Beijerinck. Biological nitrogen fixation occurs when atmospheric nitrogen is converted to ammonia by an enzyme called a nitrogenase; the overall reaction for BNF is: N2 + 16ATP + 8e- + 8H+ -> 2NH3 + H2 + 16ADP + 16PiThe process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent of H2. The conversion of N2 into ammonia occurs at a metal cluster called FeMoco, an abbreviation for the iron-molybdenum cofactor; the mechanism proceeds via a series of protonation and reduction steps wherein the FeMoco active site hydrogenates the N2 substrate. In free-living diazotrophs, the nitrogenase-generated ammonia is assimilated into glutamate through the glutamine synthetase/glutamate synthase pathway; the microbial nif genes required for nitrogen fixation are distributed in diverse environments. Nitrogenases are degraded by oxygen.
For this reason, many bacteria cease production of the enzyme in the presence of oxygen. Many nitrogen-fixing organisms exist only in anaerobic conditions, respiring to draw down oxygen levels, or binding the oxygen with a protein such as leghemoglobin. Diazotrophs are widespread within domain Bacteria including cyanobacteria, as well as green sulfur bacteria, Azotobacteraceae and Frankia. Several obligately anaerobic bacteria fix nitrogen including many Clostridium spp; some Archaea fix nitrogen, including several methanogenic taxa, which are significant contributors to nitrogen fixation in oxygen-deficient soils. Cyanobacteria inhabit nearly all illuminated environments on Earth and play key roles in the carbon and nitrogen cycle of the biosphere. In general, cyanobacteria can use various inorganic and organic sources of combined nitrogen, like nitrate, ammonium, urea, or some amino acids. Several cyanobacterial strains are capable of diazotrophic growth, an ability that may have been present in their last common ancestor in the Archean eon.
Nitrogen fixation by cyanobacteria in coral reefs can fix twice as much nitrogen as on land—around 1.8 kg of nitrogen is fixed per hectare per day. The colonial marine cyanobacterium Trichodesmium is thought to fix nitrogen on such a scale that it accounts for half of the nitrogen fixation in marine systems globally. Plants that contribute to nitrogen fixation include those of the legume family – Fabaceae – with taxa such as kudzu, soybeans, lupines and rooibos, they contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released; the great majority of legumes have this association. In many traditional and organic farming practices, fields are rotated through various types of crops, which include one consisting or of clover or buckwheat referred to as "green manure"; the efficiency of nitrogen fixation in soil is dependent on many factors, including the legume as well as air and soil conditions.
For example, nitrogen fixation by red clover can range from 50 - 200 lb./acre depending on these variables. Inga alley farming relies on the leguminous genus Inga, a small tropical, tough-leaved, nitrogen
Augustin Pyramus de Candolle
Augustin Pyramus de Candolle spelled Augustin Pyrame de Candolle was a Swiss botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at an herbarium. Within a couple of years de Candolle had established a new genus, he went on to document hundreds of plant families and create a new natural plant classification system. Although de Candolle's main focus was botany, he contributed to related fields such as phytogeography, paleontology, medical botany, economic botany. Candolle originated the idea of "Nature's war", which influenced Charles Darwin and the principle of natural selection. De Candolle recognized that multiple species may develop similar characteristics that did not appear in a common evolutionary ancestor. During his work with plants, de Candolle noticed that plant leaf movements follow a near-24-hour cycle in constant light, suggesting that an internal biological clock exists. Though many scientists doubted de Candolle's findings, experiments over a century demonstrated that ″the internal biological clock″ indeed exists.
Candolle's descendants continued his work on plant classification. Alphonse de Candolle and Casimir Pyrame de Candolle contributed to the Prodromus Systematis Naturalis Regni Vegetabilis, a catalog of plants begun by Augustin Pyramus de Candolle. Augustin Pyramus de Candolle was born on 4 February 1778 in Geneva, Switzerland, to Augustin de Candolle, a former official, his wife, Louise Eléonore Brière, his family descended from one of the ancient families of Provence in France, but relocated to Geneva at the end of the 16th century to escape religious persecution. At age seven de Candolle contracted of a severe case of hydrocephalus, which affected his childhood, he is said to have had great aptitude for learning, distinguishing himself in school with his rapid acquisition of knowledge in classical and general literature and his ability to write fine poetry. In 1794, he began his scientific studies at the Collège Calvin, where he studied under Jean Pierre Étienne Vaucher, who inspired de Candolle to make botanical science the chief pursuit of his life.
He spent four years at the Geneva Academy, studying science and law according to his father's wishes. In 1798, he moved to Paris, his botanical career formally began with the help of René Louiche Desfontaines, who recommended de Candolle for work in the herbarium of Charles Louis L'Héritier de Brutelle during the summer of 1798. The position elevated de Candolle's reputation and led to valuable instruction from Desfontaines himself. De Candolle established his first genus, Senebiera, in 1799.de Candolle's first books, Plantarum historia succulentarum and Astragalogia, brought him to the notice of Georges Cuvier and Jean-Baptiste Lamarck. de Candolle, with Cuvier's approval, acted as deputy at the Collège de France in 1802. Lamarck entrusted him with the publication of the third edition of the Flore française, in the introduction entitled Principes élémentaires de botanique, de Candolle proposed a natural method of plant classification as opposed to the artificial Linnaean method; the premise of de Candolle's method is.
In 1804, de Candolle published his Essai sur les propriétés médicales des plantes and was granted a doctor of medicine degree by the medical faculty of Paris. Two years he published Synopsis plantarum in flora Gallica descriptarum. de Candolle spent the next six summers making a botanical and agricultural survey of France at the request of the French government, published in 1813. In 1807 he was appointed professor of botany in the medical faculty of the University of Montpellier, where he would become the first chair of botany in 1810, his teaching at the University of Montpellier consisted of field classes attended by 200–300 students, starting at 5:00 am and finishing at 7:00 pm. While in Montpellier, de Candolle published his Théorie élémentaire de la botanique, which introduced a new classification system and the word taxonomy. Candolle moved back to Geneva in 1816 and in the following year was invited by the government of the Canton of Geneva to fill the newly created chair of natural history.
De Candolle spent the rest of his life in an attempt to elaborate and complete his natural system of botanical classification. De Candolle published initial work in his Regni vegetabillis systema naturale, but after two volumes he realized he could not complete the project on such a large scale, he began his less extensive Prodromus Systematis Naturalis Regni Vegetabilis in 1824. However, he was able to finish two-thirds of the whole. So, he was able to characterize over one hundred families of plants, helping to lay the empirical basis of general botany. Although de Candolle's main focus was botany, throughout his career he dabbled in fields related to botany, such as phytogeography, paleontology, medical botany, economic botany. In 1827 he was elected an associated member of the Royal Institute of the Netherlands. Augustin de Candolle was the first of four generations of botanists in the de Candolle dynasty, his son, Alphonse de Candolle, whom he fathered with his wife, Mademoiselle Torras succeeded to his father's chair in botany and continued the Prodromus.
Casimir Pyrame de Candolle, Augustin de Candolle's grandson contributed to the Prodromus through his detailed, extensive research and characterization of the Piperaceae family of plants. Augustin de Candolle's great-grandson, Richard Émile Augustin de Candolle
The rosids are members of a large clade of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms. The clade is divided into 16 to 20 orders, depending upon circumscription and classification; these orders, in turn, together comprise about 140 families. Fossil rosids are known from the Cretaceous period. Molecular clock estimates indicate that the rosids originated in the Aptian or Albian stages of the Cretaceous, between 125 and 99.6 million years ago. The name is based upon the name "Rosidae", understood to be a subclass. In 1967, Armen Takhtajan showed that the correct basis for the name "Rosidae" is a description of a group of plants published in 1830 by Friedrich Gottlieb Bartling; the clade was renamed "Rosidae" and has been variously delimited by different authors. The name "rosids" is informal and not assumed to have any particular taxonomic rank like the names authorized by the ICBN; the rosids are monophyletic based upon evidence found by molecular phylogenetic analysis.
Three different definitions of the rosids were used. Some authors included the orders Vitales in the rosids. Others excluded both of these orders; the circumscription used in this article is that of the APG IV classification, which includes Vitales, but excludes Saxifragales. The rosids and Saxifragales form the superrosids clade; this is one of three groups that compose the Pentapetalae, the others being Dilleniales and the superasterids. The rosids consist of two groups: the eurosids; the eurosids, in turn, are divided into two groups: malvids. The rosids consist of 17 orders. In addition to Vitales, there are 8 orders in malvids; some of the orders have only been recognized. These are Vitales, Crossosomatales and Huerteales; the phylogeny of Rosids shown below is adapted from the Angiosperm Phylogeny Group website. The nitrogen-fixing clade contains a high number of actinorhizal plants. Not all plants in this clade are actinorhizal, however. Media related to Rosids at Wikimedia Commons
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
The Dryadoideae subfamily of the Rosaceae consists of four genera, all of which share root nodules that host the nitrogen-fixing bacterium Frankia. They are subshrubs, shrubs, or small trees with a base chromosome number of 9, whose fruits are either an achene or an aggregate of achenes; the subfamily has at various times been separated as a tribe or subtribe. Media related to Dryadoideae at Wikimedia Commons Data related to Dryadoideae at Wikispecies