Jump to content

Geranium: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Sarr X (talk | contribs)
203 edits
No edit summary
Undid revision 630450439 by Sarr X (talk) Vandalism
Line 1: Line 1:
{{About|the botanical genus called ''Geranium''|the summer bedding plants often called "geranium"|Pelargonium|other uses}}
{{distinguish|Geranium}}
{{infobox germanium}}
{{distinguish|germanium}}
{{taxobox
{{pp-move-indef}}
|image = Geranium February 2008-1.jpg
'''Germanium''' is a [[chemical element]] with symbol '''Ge''' and [[atomic number]] 32. It is a lustrous, hard, grayish-white [[metalloid]] in the [[carbon group]], chemically similar to its group neighbors [[tin]] and [[silicon]]. Purified germanium is a [[semiconductor]], with an appearance most similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with [[oxygen]] in nature. Unlike silicon, it is too reactive to be found naturally on Earth in the free (native) state.
|image_caption = ''[[Geranium dissectum]]''
|regnum = [[Plant]]ae
|unranked_divisio = [[Angiosperms]]
|unranked_classis = [[Eudicot]]s
|unranked_ordo = [[Rosids]]
|ordo = [[Geraniales]]
|familia = [[Geraniaceae]]
|genus = '''''Geranium'''''
|genus_authority = [[Carolus Linnaeus|L.]]
|subdivision_ranks = Species
|subdivision = [[List of cranesbill species|See list.]]
|}}


'''''Geranium''''' is a [[genus]] of 422 [[species]] of flowering [[Annual plant|annual]], [[Biennial plant|biennial]], and [[Perennial plant|perennial]] [[plant]]s that are commonly known as the '''cranesbills'''. They are found throughout the [[temperateness|temperate]] regions of the world and the mountains of the tropics, but mostly in the eastern part of the [[Mediterranean region]]. The long, palmately cleft [[Leaf|leaves]] are broadly circular in form. The flowers have five petals and are coloured white, pink, purple or blue, often with distinctive veining. Geraniums will grow in any soil as long as it is not waterlogged. [[Plant propagation|Propagation]] is by semiripe cuttings in summer, by seed, or by division in autumn or spring.
Because very few minerals contain it in high concentration, germanium was discovered comparatively late in the history of chemistry. Germanium ranks near fiftieth [[Abundance of elements in Earth's crust|in relative abundance of the elements in the Earth's crust]]. In 1869, [[Dmitri Mendeleev]] [[Mendeleev's predicted elements|predicted]] its existence and some of its properties based on its position on his [[periodic table]] and called the element '''[[Mendeleev's predicted elements#Ekasilicon and germanium|ekasilicon]]'''. Nearly two decades later, in 1886, [[Clemens Winkler]] found the new element along with [[silver]] and [[sulfur]], in a rare mineral called [[argyrodite]]. Although the new element somewhat resembled [[arsenic]] and [[antimony]] in appearance, its combining ratios in the new element's compounds agreed with Mendeleev's predictions for a relative of silicon. Winkler named the element after his country, [[German Empire|Germany]]. Today, germanium is mined primarily from [[sphalerite]] (the primary ore of zinc), though germanium is also recovered commercially from [[silver]], [[lead]], and [[copper]] [[ore]]s.


The genus name is derived from the [[Greek language|Greek]] {{lang|grc|γέρανος}} (''géranos'') or {{lang|grc|γερανός}} (''geranós'') ‘crane’. The English name ‘cranesbill’ derives from the appearance of the [[fruit capsule]] of some of the species. Species in the ''Geranium'' genus have a distinctive mechanism for [[seed dispersal]]. This consists of a beak-like column which springs open when ripe and casts the seeds some distance. The fruit capsule consists of five cells, each containing one seed, joined to a column produced from the centre of the old flower. The common name ‘cranesbill’ comes from the shape of the unsprung column, which in some species is long and looks like the bill of a [[Crane (bird)|crane]]. However, many species in this genus do not have a long beak-like column.
Germanium "metal" (isolated germanium) is used as a [[semiconductor]] in [[transistor]]s and various other electronic devices. Historically the first decade of semiconductor electronics was based entirely on germanium. Today, however, its production for use in semiconductor electronics is a small fraction (2%) of that of ultra-high purity silicon, which has largely replaced it. Presently, germanium's major end uses are in [[fibre-optic]] systems, [[infrared vision|infrared optics]] and in [[solar cell]] applications. Germanium compounds are also used for [[polymerization]] catalysts and have most recently found use in the production of [[nanowire]]s. This element forms a large number of [[organometallic]] compounds, such as [[tetraethylgermane]], which are useful in [[organometallic chemistry]].


Geraniums are eaten by the [[larva]]e of some [[Lepidoptera]] species including [[brown-tail]] and [[mouse moth]].
Germanium is not thought to be an essential element for any living organism. Some complexed organic germanium compounds are being investigated as possible pharmaceuticals, though none have yet proven successful. Similar to silicon and aluminum, natural germanium compounds tend to be insoluble in water, and thus have little oral [[toxicity]]. However, synthetic soluble germanium salts are [[nephrotoxic]], and synthetic chemically reactive germanium compounds with [[halogen]]s and [[hydrogen]] are irritants and toxins.
<br style="clear:left;" />


The species ''[[Geranium viscosissimum]]'' (sticky geranium) is considered to be [[protocarnivorous]].
== History ==
{{see also|History of the transistor}}
<!--[[File:medeleeff by repin.jpg|thumb|Dmitri Mendeleev|alt=An old man with a gray-white beard sitting by the table, holding an old open book in his laps. He wears a red-blue gown and black square hat. There are two thick old books on the table.]]
[[File:Winkler Clemens.jpg|thumb|[[Clemens Winkler]]|alt=Photo of a bust of a middle-aged man in a suit with a white short beard and gray moustache.]] THESE PHOTOS are hard to arrange due to the infobox; they are not essential for Germanium-->
In his report on ''The Periodic Law of the Chemical Elements'', in 1869, the [[Russia]]n chemist Dmitri Ivanovich Mendeleev predicted the existence of several unknown [[chemical element]]s, including one that would fill a gap in the [[group 14 element|carbon family]] in his Periodic Table of the Elements, located between [[silicon]] and [[tin]].<ref>{{cite journal| first = Masanori|last = Kaji |title = D. I. Mendeleev's concept of chemical elements and ''The Principles of Chemistry''|journal=Bulletin for the History of Chemistry|volume=27|issue=1|pages=4–16|year=2002|url=http://www.scs.uiuc.edu/~mainzv/HIST/awards/OPA%20Papers/2005-Kaji.pdf| format=PDF|accessdate = 2008-08-20}}</ref> Because of its position in his Periodic Table, Mendeleev called it ''ekasilicon (Es)'', and he estimated its [[atomic weight]] as about 72.0.<!-- Mendeleev studied several minerals in an unsuccessful search for this new element.<ref name="vdk">{{cite web| title = Elementymology & Elements Multidict: Germanium|first = Peter|last = van der Krogt|url = http://elements.vanderkrogt.net/element.php?sym=Ge| accessdate = 2008-08-20}}</ref> -->


==Confusion with pelargoniums==
In mid-1885, at a mine near [[Freiberg, Saxony]], a new [[mineral]] was discovered and named ''[[argyrodite]]'', because of its high [[silver]] content.{{#tag:ref|From Greek, ''argyrodite'' means ''silver-containing''.<ref>{{cite report|url=http://www.handbookofmineralogy.org/pdfs/argyrodite.pdf|publisher=''Mineral Data Publishing''| format=PDF|title=Argyrodite—{{chem|Ag|8|GeS|6}}|accessdate=2008-09-01}}</ref>|group=n}} The chemist [[Clemens Winkler]] analyzed this new mineral, which proved to be a combination of silver, sulfur, and a new element. Winkler was able to isolate this new element and found it somewhat similar to [[antimony]], in 1886.<ref name="Winkle2"/><ref name="isolation">{{cite journal|journal = Berichte der deutschen chemischen Gesellschaft|volume = 19|issue = 1|pages = 210–211|title = Germanium, Ge, a New Nonmetal Element|language=German|first = Clemens|last = Winkler|authorlink = Clemens Winkler|year = 1887|doi = 10.1002/cber.18860190156|url = http://gallica.bnf.fr/ark:/12148/bpt6k90705g/f212.chemindefer|format=}} {{Wayback |date=20081207033757 |url=http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Disc-of-Germanium.html |title=English translation}}</ref> Before Winkler published his results on the new element, he decided that he would name his element ''neptunium'', since the recent discovery of planet [[Neptune]] in 1846 had been preceded by mathematical predictions of its existence.{{#tag:ref|Just as the existence of the new element had been predicted, the existence of the planet [[Neptune]] had been predicted in about 1843 by the two mathematicians [[John Couch Adams]] and [[Urbain Le Verrier]], using the calculation methods of [[celestial mechanics]]. They did this in attempts to explain the fact that the planet [[Uranus]], upon very close observation, appeared to be being pulled slightly out of position in the sky.<ref>{{cite journal|first=J. C.|last=Adams|bibcode=1846MNRAS...7..149A|title=Explanation of the observed irregularities in the motion of Uranus, on the hypothesis of disturbance by a more distant planet|journal=[[Monthly Notices of the Royal Astronomical Society]]|volume=7|page=149|date=November 13, 1846|publisher=Blackwell Publishing}}</ref> [[James Challis]] started searching for it in July 1846, and he sighted this planet on September 23, 1846.<ref>{{cite journal|first=Rev. J.|last=Challis|bibcode=1846MNRAS...7..145C|title=Account of observations at the Cambridge observatory for detecting the planet exterior to Uranus|journal=Monthly Notices of the Royal Astronomical Society|volume=7|pages=145–149|date=November 13, 1846|publisher=Blackwell Publishing}}</ref>|group=n}} However, the name "neptunium" had already been given to another proposed chemical element (though not the element that today bears the name [[neptunium]], which was discovered in 1940),{{#tag:ref|R. Hermann published claims in 1877 of his discovery of a new element beneath [[tantalum]] in the periodic table, which he named ''neptunium'', after the Greek god of the oceans and seas.<ref>{{cite journal| title=Scientific Miscellany| journal= The Galaxy |volume= 24| issue= 1|date=July 1877|page= 131| isbn=0-665-50166-8| first =Robert|last = Sears|publisher=Siebert &amp; Lilley| location=Columbus, O[hio]| oclc=16890343 243523661 77121148}}</ref><ref>{{cite journal|title=Editor's Scientific Record| journal=Harper's new monthly magazine| volume= 55|issue=325|date=June 1877 |pages= 152–153 |url = http://cdl.library.cornell.edu/cgi-bin/moa/moa-cgi?notisid=ABK4014-0055-21}}</ref> However this [[metal]] was later recognized to be an [[alloy]] of the elements [[niobium]] and tantalum.<ref>{{cite web| title = Elementymology & Elements Multidict: Niobium| first = Peter|last =van der Krogt|url = http://elements.vanderkrogt.net/element.php?sym=Nb| accessdate = 2008-08-20}}</ref> The name "[[neptunium]]" was much later given to the synthetic element one step past [[uranium]] in the Periodic Table, which was discovered by [[nuclear physics]] researchers in 1940.<ref>{{cite book |title=Nobel Lectures, Chemistry 1942–1962 |publisher=Elsevier |year=1964 |chapter=The Nobel Prize in Chemistry 1951: presentation speech| first =A.|last =Westgren|url =http://nobelprize.org/nobel_prizes/chemistry/laureates/1951/press.html}}</ref>|group=n}} so instead, Winkler named the new element ''germanium'' (from the [[Latin]] word, ''Germania'', for [[Germany]]) in honor of his homeland.<ref name="isolation" /> Argyrodite proved empirically to be Ag<sub>8</sub>GeS<sub>6</sub>.
[[File:Geranium sanguineum02.jpg|thumb|right|Showing the "bill" and seed dispersal mechanism of ''Geranium pratense'']]
Confusingly, "geranium" is also the [[common name]] of members of the genus ''[[Pelargonium]]'' (sometimes known as 'storksbill'), which are also in the [[Geraniaceae]] [[family (biology)|family]]. These are generally half-[[hardiness (plants)|hardy]] plants which are either grown from seed every year, or offered as [[bedding (horticulture)|bedding]] in spring and discarded after flowering. [[Linnaeus]] originally included all the species in one genus, ''Geranium'', but they were later separated into two genera by [[Charles L’Héritier]] in 1789. Other former members of the genus are now classified in genus ''[[Erodium]]'', including the plants known as filarees in North America.


The term "hardy geranium" is often applied to geraniums to distinguish them from the pelargoniums. However, not all geranium species are winter-hardy (see below).
Because this new element showed some similarities with the elements [[arsenic]] and antimony, its proper place in the periodic table was under consideration, but its similarities with Dmitri Mendeleev's predicted element "ekasilicon" confirmed that it belonged in this place on the periodic table.<ref name="isolation" /><ref>{{cite journal|journal = The Manufacturer and Builder|url = http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fmanu%2Fmanu0018%2F&tif=00187.TIF|year = 1887| title = Germanium, a New Non-Metallic Element|page =181| accessdate = 2008-08-20}}</ref> With further material from 500&nbsp;kg of ore from the mines in Saxony, Winkler confirmed the chemical properties of the new element in 1887.<ref name="Winkle2">{{cite journal|first = Clemens|last = Winkler|authorlink = Clemens Winkler|journal = J. Prak. Chemie|volume = 36|issue = 1|year = 1887 |pages = 177–209|title = Mittheilungen über des Germanium. Zweite Abhandlung |doi = 10.1002/prac.18870360119|url = http://gallica.bnf.fr/ark:/12148/bpt6k90799n/f183.table| accessdate = 2008-08-20| language=German}}</ref><ref name="isolation"/><ref>{{cite journal|first = O.|last = Brunck|title = Obituary: Clemens Winkler|journal = Berichte der deutschen chemischen Gesellschaft|volume= 39|issue = 4|year = 1886|pages=4491–4548|doi = 10.1002/cber.190603904164|language=German}}</ref> He also determined an atomic weight of 72.32 by analyzing pure [[germanium tetrachloride]] ({{chem|GeCl|4}}), while [[Lecoq de Boisbaudran]] deduced 72.3 by a comparison of the lines in the spark [[spectrum]] of the element.<ref>{{cite journal|title = Sur le poids atomique du germanium|first = M. Lecoq|last = de Boisbaudran|journal = Comptes rendus|year = 1886|volume = 103 |page = 452|url = http://gallica.bnf.fr/ark:/12148/bpt6k3059r/f454.table|accessdate = 2008-08-20| language=French}}</ref>


===Structure===
Winkler was able to prepare several new compounds of germanium, including its [[fluoride]]s, [[chloride]]s, [[sulfide]]s, [[germanium dioxide]], and [[tetraethylgermane]] (Ge(C<sub>2</sub>H<sub>5</sub>)<sub>4</sub>), the first organogermane.<ref name="Winkle2" /> The physical data from these compounds — which corresponded well with Mendeleev's predictions — made the discovery an important confirmation of Mendeleev's idea of element [[Periodic table|periodicity]]. Here is a comparison between the prediction and Winkler's data:<ref name="Winkle2" />
The shape of the flowers offers one way of distinguishing between the two genera ''Geranium'' and ''Pelargonium''. ''Geranium'' flowers have five very similar petals, and are thus radially symmetrical ([[actinomorphic]]), whereas pelargonium flowers have two upper petals which are different from the three lower petals, so the flowers have a single plane of symmetry ([[zygomorphic]]).


==Cultivation==
<div style="float: center; margin: 5px;">
<!-- repetitive :''See also the [[List of cranesbill species]]''.-->
{| class="wikitable"
|-
! Property !! Ekasilicon !! Germanium
|-
| atomic mass || 72.64 || 72.59
|-
| density (g/cm<sup>3</sup>) || 5.5 || 5.35
|-
| melting point (°C) || high || 947
|-
| color || gray || gray
|-
| oxide type || [[refractory]] dioxide || refractory dioxide
|-
| oxide density (g/cm<sup>3</sup>) || 4.7 || 4.7
|-
| oxide activity || feebly basic || feebly basic
|-
| chloride boiling point (°C) || under 100 || 86 (GeCl<sub>4</sub>)
|-
| chloride density (g/cm<sup>3</sup>) || 1.9 || 1.9
|}</div>
Until the late 1930s, germanium was thought to be a poorly conducting [[metal]].<ref name="DOE">{{cite web|title=Germanium: From Its Discovery to SiGe Devices|author= Haller, E. E| work=Department of Materials Science and Engineering, University of California, Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, |url=http://www.osti.gov/bridge/servlets/purl/922705-bthJo6/922705.PDF| format=PDF| accessdate=2008-08-22}}</ref> Germanium did not become economically significant until after 1945, when its properties as a semiconductor were recognized as being useful in [[electronics]]. During [[World War II]], small amounts of germanium had begun to be used in some special [[electronics|electronic devices]], mostly [[diode]]s.<ref>{{cite news| author = W. K.|url = http://select.nytimes.com/gst/abstract.html?res=F30715FE3F5B157A93C2A8178ED85F478585F9|publisher = NY Times| title = Germanium for Electronic Devices| accessdate=2008-08-22 | date=1953-05-10}}</ref><ref>{{cite web|url = http://www.computerhistory.org/semiconductor/timeline/1941-semiconductor.html|title = 1941 – Semiconductor diode rectifiers serve in WW II|publisher = Computer History Museum| accessdate=2008-08-22}}</ref> Its first major use was the point-contact [[Schottky diode]]s for [[radar]] pulse detection during the War.<ref name="DOE" /> The first [[silicon-germanium]] alloys were obtained in 1955.<ref>{{cite web|url = http://www.sp.phy.cam.ac.uk/~SiGe/Silicon%20Germanium%20(SiGe)%20History.html|title = SiGe History|publisher = [[University of Cambridge]]| accessdate=2008-08-22}}</ref> Before 1945, only a few hundred kilograms of germanium were produced in smelters each year, but by the end of the 1950s, the annual worldwide production had reached 40 [[metric ton]]s.<ref name="acs">{{cite news|url=http://pubs.acs.org/cen/80th/print/germanium.html| year=2003| title=Germanium| first = Bethany|last = Halford| work= Chemical & Engineering News |publisher= American Chemical Society| accessdate=2008-08-22}}</ref>


A number of geranium species are cultivated for horticultural use and for pharmaceutical products.
The development of the germanium [[transistor]] in 1948<ref>{{cite journal|journal = Physical Reviews|volume = 74|issue = 2|pages = 230–231|title = The Transistor, A Semi-Conductor Triode |first = J.|last = Bardeen|author2=Brattain, W. H.| year = 1948|doi = 10.1103/PhysRev.74.230|bibcode = 1948PhRv...74..230B }}</ref> opened the door to countless applications of [[solid state (electronics)|solid state electronics]].<ref>{{cite web|title = Electronics History 4 – Transistors|url = http://www.greatachievements.org/?id=3967|publisher = National Academy of Engineering|accessdate=2008-08-22}}</ref> From 1950 through the early 1970s, this area provided an increasing market for germanium, but then high-purity silicon began replacing germanium in transistors, diodes, and [[rectifier]]s.<ref name="usgs">{{cite journal|title=Germanium—Statistics and Information| author=U.S. Geological Survey|year=2008|journal=U.S. Geological Survey, Mineral Commodity Summaries|url=http://minerals.usgs.gov/minerals/pubs/commodity/germanium/ |quote=Select 2008| accessdate=2008-08-28}}</ref> For example, the company that became [[Fairchild Semiconductor]] was founded in 1957 with the express purpose of producing silicon transistors. Silicon has superior electrical properties, but it requires much greater purity, which could not be commercially achieved in the early years of [[solid-state electronics|semiconductor electronics]].<ref>{{cite journal|journal=IEEE Transactions on Electron Devices|volume = ED-23|issue = 7|date=July 1976|title = Single Crystals of Germanium and Silicon-Basic to the Transistor and Integrated Circuit|first = Gordon K.|last = Teal |pages = 621–639|doi=10.1109/T-ED.1976.18464}}</ref>
Some of the more commonly grown species include:
{|
|- valign=top
|
*''[[Geranium cinereum]]''
*''[[Geranium clarkei]]'' (Clark's geranium)
*''[[Geranium dalmaticum]]''
*''[[Geranium endressii]]'' (Endres's cranesbill)
*''[[Geranium fremontii]]'' (Fremont's geranium)
*''[[Geranium himalayense]]'', often sold under ''Geranium grandiflorum''
*''[[Geranium ibericum]]'' (Caucasus geranium),
*''[[Geranium macrorrhizum]]'' (bigroot cranesbill or bigroot geranium)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*''[[Geranium maculatum]]'' (wild geranium)
*''[[Geranium maderense]]'' (giant herb robert)
|
*''[[Geranium × magnificum]]'' (showy geranium)
*''[[Geranium phaeum]]''
*''[[Geranium platypetalum]]'' (broad-petaled geranium)
*''[[Geranium pratense]]'' (meadow cranesbill)
*''[[Geranium psilostemon]]'' (Armenian cranesbill)
*''[[Geranium renardii]]'' (Renard geranium)
*''[[Geranium sanguineum]]'' (bloody cranesbill)
*''[[Geranium subcaulescens]]'' (grey cranesbill)
*''[[Geranium sylvaticum]]'' (wood cranesbill)
|}
All the above species are perennials and generally winter-hardy plants, grown for their attractive flowers and foliage. They are long-lived and most have a mounding habit, with palmately lobed foliage. Some species have spreading rhizomes. They are normally grown in part shade to full sun, in well-draining but moisture retentive soils, rich in [[humus]].<ref name=Phillips1993>{{Citation | last1 = Phillips | first1 = Ellen | last2 = Colston Burrell | first2 = C. | year = 1993 | title = Rodale's illustrated encyclopedia of perennials | pages = 373–76 | isbn = 0-87596-570-9 | publisher = Rodale Press| location = Emmaus, Pa.}}</ref> Other perennial species grown for their flowers and foliage include: ''[[Geranium argenteum|G. argenteum]]'', ''G. eriostemon'', ''G. farreri'', ''[[Geranium nodosum|G. nodosum]]'', ''G. procurrens'', ''G. pylzowianum'', ''[[Geranium renardii|G. renardii]]'', ''G. traversii'', ''G. tuberosum'', ''G. versicolor'', ''[[Geranium wallichianum|G. wallichianum]]'' and ''G. wlassovianum''. Some of these are not winter-hardy in cold areas and are grown in specialized gardens like rock gardens.<ref name=Jelitto1990>{{Citation| last1 = Jelitto | first1 = Leo| last2 = Schacht | first2 = Wilhelm| last3 = Epp | first3 = Translated by Michael E.| last4 = John Philip Baumgardt | first4 = Technical Editor | year = 1990| title = Hardy herbaceous perennials| volume = 1| pages = 260–64| isbn = 0-88192-159-9| publisher = Timber Press| location = Portland, Or. }}</ref> ''Geranium'' 'Johnson's Blue' is a hybrid between ''G. himalayense'' (southwestern China), with ''G. pratense'' (European meadow cranesbill).<ref>{{cite web|url=http://www.paghat.com/cranesbilljohnsons.html |title=Paghat's Garden |publisher=Paghat.com |date= |accessdate=2013-09-17}}</ref>


The following hybrid [[cultivars]] have gained the [[Royal Horticultural Society]]'s [[Award of Garden Merit]] (other cultivars are dealt with under their species name - see above).
Meanwhile, the demand for germanium for use in [[fiber optics]] communication networks, infrared [[night vision]] systems, and [[polymerization]] [[catalysts]] increased dramatically.<ref name="acs" /> These end uses represented 85% of worldwide germanium consumption in 2000.<ref name="usgs" /> The US government even designated germanium as a strategic and critical material, calling for a 146&nbsp;[[Short ton|ton]] (132&nbsp;[[Tonne|t]]) supply in the national defense stockpile in 1987.<ref name="acs" />
{|

|- valign=top
Germanium differs from silicon in that the supply for germanium is limited by the availability of exploitable sources, while the supply of silicon is only limited by production capacity since silicon comes from ordinary sand or [[quartz]]. As a result, while silicon could be bought in 1998 for less than $10 per kg,<ref name="acs" /> the price of 1&nbsp;kg of germanium was then almost $800.<ref name="acs" />
|

*'Ann Folkard'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=857 |title=RHS Plant Selector Geranium 'Ann Folkard' AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
== Characteristics ==
*'Dilys'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=5747 |title=RHS Plant Selector Geranium 'Dilys' AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
Under [[standard conditions]] germanium is a brittle, silvery-white, semi-metallic element.<ref name="nbb"/> This form constitutes an [[allotrope]] technically known as ''α-germanium'', which has a metallic luster and a [[diamond cubic|diamond cubic crystal structure]], the same as [[diamond]].<ref name="usgs" /> At pressures above 120 [[bar (unit)|kbar]], a different allotrope known as ''β-germanium'' forms, which has the same structure as β-[[tin]].<ref name="HollemanAF"/> Along with silicon, [[gallium]], [[bismuth]], [[antimony]], and [[water]], it is one of the few substances that expands as it solidifies (i.e. [[freezing|freezes]]) from its molten state.<ref name="HollemanAF"/>
*'Johnson's Blue'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=861 |title=RHS Plant Selector Geranium 'Johnson's Blue' / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>

*'Mavis Simpson'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=6057 |title=RHS Plant Selector Geranium 'Mavis Simpson' AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
Germanium is a [[semiconductor]]. [[Zone refining]] techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 10<sup>10</sup>,<ref name="lanl">{{cite web|url=http://periodic.lanl.gov/32.shtml|publisher=Los Alamos National Laboratory|title=Germanium|accessdate=2008-08-28}}</ref> making it one of the purest materials ever obtained.<ref>{{cite book |title=The Primordial Universe: 28 June – 23 July 1999 |editor=Binetruy, B |author=Chardin, B. |chapter=Dark Matter: Direct Detection |publisher=Springer |year=2001 |isbn=3-540-41046-5 |page=308}}</ref> The first metallic material discovered (in 2005) to become a [[superconductor]] in the presence of an extremely strong [[electromagnetic field]] was an [[Uranium rhodium germanium|alloy of germanium with uranium and rhodium]].<ref>{{cite journal|doi = 10.1126/science.1115498|date=August 2005|last =Lévy| first= F.|coauthors = Sheikin, I.; Grenier, B.; Huxley, Ad.|title=Magnetic field-induced superconductivity in the ferromagnet URhGe|volume=309|issue=5739|pages=1343–1346|pmid=16123293|journal=Science|bibcode = 2005Sci...309.1343L }}</ref>
|

*'Orion'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=6349 |title=RHS Plant Selector Geranium 'Orion' AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
Pure germanium is known to spontaneously extrude very long [[screw dislocation]]s. They are one of the primary reasons for the failure of older diodes and transistors made from germanium; depending on what they eventually touch, they may lead to an [[electrical short]].
*'Rozanne'<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=4832 |title=RHS Plant Selector Geranium ROZANNE 'Gerwat' PBR AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>

*'A. T. Johnson' (''G.'' × ''oxonianum'')<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/plant?plantid=872 |title=RHS Plant Selector Geranium × oxonianum 'A.T. Johnson' AGM / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
=== Chemistry ===
*'Wargrave pink' (''G.'' × ''oxonianum'')<ref>{{cite web|url=http://apps.rhs.org.uk/plantselector/searchbynameresults?nm=geranium+agm&op=0&pn=4 |title=RHS Plant Selector Results / RHS Gardening |publisher=Apps.rhs.org.uk |date= |accessdate=2013-09-17}}</ref>
{{category see also|Germanium compounds}}
Elemental germanium oxidizes slowly to [[germanium dioxide|GeO<sub>2</sub>]] at 250&nbsp;°C.<ref>{{cite journal|doi=10.1016/S0169-4332(98)00251-7|title=KRXPS study of the oxidation of Ge(001) surface|year=1998|author=Tabet, N|journal=Applied Surface Science|volume=134|issue=1–4|page=275|bibcode = 1998ApSS..134..275T|last2=Salim|first2=Mushtaq A. }}</ref> Germanium is insoluble in dilute [[acids]] and [[alkalis]] but dissolves slowly in concentrated [[sulfuric acid]] and reacts violently with molten alkalis to produce [[germanate]]s ({{chem|[GeO|3|]|2−}}). Germanium occurs mostly in the [[oxidation state]] +4 although many compounds are known with the oxidation state of +2.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> Other oxidation states are rare, such as +3 found in compounds such as Ge<sub>2</sub>Cl<sub>6</sub>, and +3 and +1 observed on the surface of oxides,<ref>{{cite journal|doi=10.1016/S0368-2048(98)00451-4|title=XPS study of the growth kinetics of thin films obtained by thermal oxidation of germanium substrates|first3=A.L|last3=Al-Oteibi|first2=M.A|year=1999|last2=Salim|author=Tabet, N|journal=Journal of Electron Spectroscopy and Related Phenomena|volume=101–103|page=233}}</ref> or negative oxidation states in [[germane]]s, such as −4 in {{chem|GeH|4}}. Germanium cluster anions ([[Zintl phase|Zintl]] ions) such as Ge<sub>4</sub><sup>2−</sup>, Ge<sub>9</sub><sup>4−</sup>, Ge<sub>9</sub><sup>2−</sup>, [(Ge<sub>9</sub>)<sub>2</sub>]<sup>6−</sup> have been prepared by the extraction from alloys containing alkali metals and germanium in liquid ammonia in the presence of [[ethylenediamine]] or a [[cryptand]].<ref name = "Greenwood"/><ref>{{cite journal|title=Oxidative Coupling of Deltahedral [Ge<sub>9</sub>]<sup>4−</sup> Zintl Ions|first1 = Li|last1 = Xu|last2=Sevov| first2=Slavi C.|journal=J. Am. Chem. Soc.|year = 1999|volume = 121| issue = 39|pages = 9245–9246|doi = 10.1021/ja992269s}}</ref> The oxidation states of the element in these ions are not integers—similar to the [[ozonide]]s O<sub>3</sub><sup>−</sup>.

Two [[oxide]]s of germanium are known: [[germanium dioxide]] ({{chem|GeO|2}}, germania) and [[germanium monoxide]], ({{chem|GeO}}).<ref name="HollemanAF">{{cite book|last = Holleman|first = A. F.|coauthors = Wiberg, E.; Wiberg, N.|title=Lehrbuch der Anorganischen Chemie, 102nd ed|publisher=de Gruyter|year=2007|isbn=978-3-11-017770-1|oclc = 145623740 180963521 219549154}}</ref> The dioxide, GeO<sub>2</sub> can be obtained by roasting [[germanium disulfide]] ({{chem|GeS|2}}), and is a white powder that is only slightly soluble in water but reacts with alkalis to form germanates.<ref name="HollemanAF"/> The monoxide, germanous oxide, can be obtained by the high temperature reaction of GeO<sub>2</sub> with Ge metal.<ref name="HollemanAF"/> The dioxide (and the related oxides and germanates) exhibits the unusual property of having a high refractive index for visible light, but transparency to [[infrared]] light.<ref>{{cite journal|doi = 10.1111/j.1151-2916.2002.tb00594.x|title = Infrared Transparent Germanate Glass-Ceramics|first = Shyam S.|last = Bayya|coauthors = Sanghera, Jasbinder S.; Aggarwal, Ishwar D.; Wojcik, Joshua A.|journal = Journal of the American Ceramic Society|volume = 85|issue = 12|pages= 3114–3116|year = 2002}}</ref><ref>{{cite journal|doi = 10.1007/BF00614256|title = Infrared reflectance and transmission spectra of germanium dioxide and its hydrolysis products|year = 1975 |last = Drugoveiko|first = O. P.|journal = Journal of Applied Spectroscopy|volume = 22|issue = 2|page = 191|last2 = Evstrop'ev|first2 = K. K.|last3 = Kondrat'eva|first3 = B. S.|last4 = Petrov|first4 = Yu. A.|last5 = Shevyakov|first5 = A. M.|bibcode=1975JApSp..22..191D}}</ref> [[Bismuth germanate]], Bi<sub>4</sub>Ge<sub>3</sub>O<sub>12</sub>, (BGO) is used as a [[scintillator]].<ref name="BGO">{{cite journal|title = A Bismuth Germanate-Avalanche Photodiode Module Designed for Use in High Resolution Positron Emission Tomography|last = Lightstone|first = A. W.|coauthors = McIntyre, R. J.; Lecomte, R.; Schmitt, D.|journal = IEEE Transactions on Nuclear Science| year = 1986|volume =33|issue= 1|pages = 456–459|doi =10.1109/TNS.1986.4337142|bibcode = 1986ITNS...33..456L }}</ref>

[[Binary compound]]s with other [[chalcogen]]s are also known, such as the di[[sulfide]] ({{chem|GeS|2}}), di[[selenide]] ({{chem|GeSe|2}}), and the monosulfide (GeS), selenide (GeSe), and [[Telluride (chemistry)|telluride]] (GeTe).<ref name = "Greenwood"/> GeS<sub>2</sub> forms as a white precipitate when hydrogen sulfide is passed through strongly acid solutions containing Ge(IV).<ref name = "Greenwood"/> The disulfide is appreciably soluble in water and in solutions of caustic alkalis or alkaline sulfides. Nevertheless, it is not soluble in acidic water, which allowed Winkler to discover the element.<ref>{{cite journal|first =Otto H.|last = Johnson|title = Germanium and its Inorganic Compounds|journal = Chem. Rev.|year = 1952|volume= 3|issue =3| page=431|doi = 10.1021/cr60160a002}}</ref> By heating the disulfide in a current of [[hydrogen]], the monosulfide (GeS) is formed, which sublimes in thin plates of a dark color and metallic luster, and is soluble in solutions of the caustic alkalis.<ref name="HollemanAF"/> Upon melting with [[alkali metal compound|alkaline carbonates]] and [[sulfur]], germanium compounds form salts known as thiogermanates.<ref>{{cite journal|doi=10.1039/a703634e|title=First synthesis of mesostructured thiogermanates|year=1997|last = Fröba|first = Michael |journal=Chemical Communications|issue=18|page=1729|last2=Oberender|first2=Nadine}}</ref>

[[File:Germane-2D-dimensions.png|upright|left|thumb|Germane is similar to [[methane]].|alt=Skeletal chemical structure of a tetrahedral molecule with germanium atom in its center bonded to four hydrogen atoms. The Ge-H distance is 152.51 picometers.]]
Four tetra[[halides]] are known. Under normal conditions GeI<sub>4</sub> is a solid, GeF<sub>4</sub> a gas and the others volatile liquids. For example, [[germanium tetrachloride]], GeCl<sub>4</sub>, is obtained as a colorless fuming liquid boiling at 83.1&nbsp;°C by heating the metal with chlorine.<ref name="HollemanAF"/> All the tetrahalides are readily hydrolyzed to hydrated germanium dioxide.<ref name="HollemanAF"/> GeCl<sub>4</sub> is used in the production of organogermanium compounds.<ref name = "Greenwood"/> All four dihalides are known and in contrast to the tetrahalides are polymeric solids.<ref name = "Greenwood"/> Additionally Ge<sub>2</sub>Cl<sub>6</sub> and some higher compounds of formula Ge<sub>''n''</sub>Cl<sub>2''n''+2</sub> are known.<ref name="HollemanAF"/> The unusual compound Ge<sub>6</sub>Cl<sub>16</sub> has been prepared that contains the Ge<sub>5</sub>Cl<sub>12</sub> unit with a [[neopentane]] structure.<ref>{{cite journal|title = The Crystal Structure and Raman Spectrum of Ge<sub>5</sub>Cl<sub>12</sub>·GeCl<sub>4</sub> and the Vibrational Spectrum of Ge<sub>2</sub>Cl<sub>6</sub>| last = Beattie|first = I.R.|coauthors = Jones, P.J.; Reid, G.; Webster, M.;|journal = Inorg. Chem.|volume = 37|issue =23|pages = 6032–6034|year = 1998|doi =10.1021/ic9807341|pmid = 11670739}}</ref>

[[Germane]] (GeH<sub>4</sub>) is a compound similar in structure to [[methane]]. Polygermanes—compounds that are similar to [[alkane]]s—with formula Ge<sub>''n''</sub>H<sub>2''n''+2</sub> containing up to five germanium atoms are known.<ref name = "Greenwood"/> The germanes are less volatile and less reactive than their corresponding silicon analogues.<ref name = "Greenwood"/> GeH<sub>4</sub> reacts with alkali metals in liquid ammonia to form white crystalline MGeH<sub>3</sub> which contain the GeH<sub>3</sub><sup>−</sup> [[anion]].<ref name = "Greenwood"/> The germanium hydrohalides with one, two and three halogen atoms are colorless reactive liquids.<ref name = "Greenwood"/>

[[File:NucleophilicAdditionWithOrganogermanium.png|right|thumb|[[Nucleophile|Nucleophilic]] addition with an organogermanium compound.|alt=Skeletal chemical structures outlining an additive chemical reaction including an organogermanium compound.]]
The first [[organogermanium compound]] was synthesized by Winkler in 1887; the reaction of germanium tetrachloride with [[diethylzinc]] yielded [[tetraethylgermane]] ({{chem|Ge(C|2|H|5|)|4}}).<ref name="Winkle2" /> Organogermanes of the type R<sub>4</sub>Ge (where R is an [[alkyl]]) such as [[tetramethylgermane]] ({{chem|Ge(CH|3|)|4}}) and tetraethylgermane are accessed through the cheapest available germanium precursor [[germanium tetrachloride]] and alkyl nucleophiles. Organic germanium hydrides such as [[isobutylgermane]] ({{chem|(CH|3|)|2|CHCH|2|GeH|3}}) were found to be less hazardous and may be used as a liquid substitute for toxic [[germane]] gas in [[semiconductor]] applications. Many germanium [[reactive intermediate]]s are known: [[-yl|germyl]] [[free radical]]s, germylenes (similar to [[carbene]]s), and germynes (similar to [[carbyne]]s).<ref>{{cite journal|title = Reactive intermediates in organogermanium chemistry|first = Jacques|last = Satge|journal = Pure & Appl. Chem.|volume = 56|issue = 1|pages = 137–150|year =1984|doi = 10.1351/pac198456010137}}</ref><ref>{{cite journal|title = Organogermanium Chemistry| first = Denis|last = Quane|author2=Bottei, Rudolph S.|journal = Chemical Reviews|volume = 63|issue = 4|pages = 403–442|year =1963|doi = 10.1021/cr60224a004}}</ref> The organogermanium compound [[Propagermanium|2-carboxyethylgermasesquioxane]] was first reported in the 1970s, and for a while was used as a dietary supplement and thought to possibly have anti-tumor qualities.<ref name="toxic" />

Using a ligand called Eind (1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl) germanium is able to form a double bond with oxygen (germanone).<ref>{{cite news|last=Broadwith|first=Phillip|title=Germanium-oxygen double bond takes centre stage|url=http://www.rsc.org/chemistryworld/News/2012/March/germanone-germanium-oxygen-double-bond-created.asp|accessdate=2014-05-15|newspaper=Chemistry World|date=25 March 2012}}</ref>

=== Isotopes ===
{{main|Isotopes of germanium}}
Germanium has five naturally occurring [[isotope]]s, {{SimpleNuclide2|Germanium|70}}, {{SimpleNuclide2|Germanium|72}}, {{SimpleNuclide2|Germanium|73}}, {{SimpleNuclide2|Germanium|74}}, {{SimpleNuclide2|Germanium|76}}. Of these, {{SimpleNuclide2|Germanium|76}} is very slightly radioactive, decaying by [[double beta decay]] with a [[half-life]] of {{val|1.78|e=21|u=years}}. {{SimpleNuclide2|Germanium|74}} is the most common isotope, having a [[natural abundance]] of approximately 36%. {{SimpleNuclide2|Germanium|76}} is the least common with a natural abundance of approximately 7%.<ref name="nubase">{{cite journal| last = Audi|first = G.| title = Nubase2003 Evaluation of Nuclear and Decay Properties| journal = Nuclear Physics A| volume = 729| issue = 1| pages = 3–128| publisher = Atomic Mass Data Center| year = 2003| doi=10.1016/j.nuclphysa.2003.11.001| bibcode=2003NuPhA.729....3A| last2 = Bersillon| first2 = O.| last3 = Blachot| first3 = J.| last4 = Wapstra| first4 = A.H.}}</ref> When bombarded with alpha particles, the isotope {{SimpleNuclide2|Germanium|72}} will generate stable {{SimpleNuclide2|Selenium|77|link=yes}}, releasing high energy electrons in the process.<ref name="72Ge" /> Because of this, it is used in combination with radon for [[Atomic battery|nuclear batteries]].<ref name="72Ge">Perreault, Bruce A. [http://www.google.com/patents/US7800286 "Alpha Fusion Electrical Energy Valve"], US Patent 7800286, issued September 21, 2010. {{Wayback |date=20071012103442 |url=http://www.nuenergy.org/disclosures/AlphaFusionPatent_05-04-2007.pdf |title=PDF copy}}.</ref>

At least 27 [[radioisotope]]s have also been synthesized ranging in atomic mass from 58 to 89. The most stable of these is {{SimpleNuclide2|Germanium|68}}, decaying by [[electron capture]] with a half-life of {{val|270.95|u=days}}. The least stable is {{SimpleNuclide2|Germanium|60}} with a half-life of {{val|30|ul=ms}}. While most of germanium's radioisotopes decay by [[beta decay]], {{SimpleNuclide2|Germanium|61}} and {{SimpleNuclide2|Germanium|64}} decay by [[Positron emission|{{SubatomicParticle|beta+}}]] delayed [[proton emission]].<ref name="nubase"/> {{SimpleNuclide2|Germanium|84}} through {{SimpleNuclide2|Germanium|87}} isotopes also exhibit minor [[Beta decay|{{SubatomicParticle|beta-}}]] delayed [[neutron emission]] decay paths.<ref name="nubase"/>

=== Occurrence ===
{{category see also|Germanium minerals}}

Germanium is created through [[stellar nucleosynthesis]], mostly by the [[s-process]] in [[asymptotic giant branch]] stars. The s-process is a slow [[neutron]] capture of lighter elements inside pulsating [[red giant]] stars.<ref name="sterling">{{cite journal|journal = The Astrophysical Journal Letters|volume = 578|issue = 1|pages = L55–L58|year = 2002|doi = 10.1086/344473|title = Discovery of Enhanced Germanium Abundances in Planetary Nebulae with the Far Ultraviolet Spectroscopic Explorer|first = N. C.|last = Sterling|coauthors = Dinerstein, Harriet L.; Bowers, Charles W.|bibcode=2002ApJ...578L..55S|arxiv = astro-ph/0208516 }}</ref> Germanium has been detected in the atmosphere of Jupiter<ref>{{cite journal| title= The tropospheric gas composition of Jupiter's north equatorial belt /NH<sub>3</sub>, PH<sub>3</sub>, CH<sub>3</sub>D, GeH<sub>4</sub>, H<sub>2</sub>O/ and the Jovian D/H isotopic ratio| last = Kunde| first = V.|author2=Hanel, R. |author3=Maguire, W. |author4=Gautier, D. |author5=Baluteau, J. P. |author6=Marten, A. |author7=Chedin, A. |author8=Husson, N. |author9= Scott, N. |displayauthors=9 |journal = Astrophysical Journal| volume= 263|year= 1982|pages= 443–467|doi=10.1086/160516| bibcode=1982ApJ...263..443K}}</ref> and in some of the most distant stars.<ref>{{cite journal| journal=Nature|volume=423|issue= 29|date=2003-05-01| pmid=12721614| doi=10.1038/423029a|title=Astronomy: Elements of surprise| last = Cowan|first = John| page=29|bibcode = 2003Natur.423...29C }}</ref> Its abundance [[Earth#Chemical composition|in the Earth's crust]] is approximately 1.6&nbsp;[[Parts per million|ppm]].<ref name="Holl">{{cite journal| doi = 10.1016/j.oregeorev.2005.07.034|title = Metallogenesis of germanium—A review|first = R.|last = Höll|coauthors = Kling, M.; Schroll, E.| journal = Ore Geology Reviews|volume = 30|issue = 3–4|year = 2007| pages = 145–180}}</ref> There are only a few minerals like [[argyrodite]], [[briartite]], [[germanite]], and [[renierite]] that contain appreciable amounts of germanium, but no mineable deposits exist for any of them.<ref name="usgs" /><ref>{{cite web|url=http://web.archive.org/web/20070612043415/http://www.resourceinvestor.com/pebble.asp?relid=31285|publisher=Resource Investor.com|accessdate=2008-09-09|title=Byproducts II: Another Germanium Rush? |first=Jack|last = Lifton|date=2007-04-26}}</ref><!--Ore found in the Pend Orielle Mine near [[Detroit]] has exceptionally high amounts of germanium.<ref>http://periodictable.com/Elements/032/index.html</ref><ref>{{Cite doi | 10.2307/30056827 }}</ref>--> Some zinc-copper-lead ore bodies contain enough germanium that it can be extracted from the final ore concentrate.<ref name="Holl" />
An unusual enrichment process causes a high content of germanium in some coal seams, which was discovered by [[Victor Moritz Goldschmidt]] during a broad survey for germanium deposits.<ref name="Gold1">{{cite journal|journal = Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse|title = Ueber das Vorkommen des Germaniums in Steinkohlen und Steinkohlenprodukten|last = Goldschmidt| first = V. M.|pages = 141–167| year = 1930|url =http://resolver.sub.uni-goettingen.de/purl?GDZPPN002508303}}</ref><ref name="Gold2">{{cite journal|journal = Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse|title = Zur Geochemie des Germaniums|last = Goldschmidt| first = V. M.|author2=Peters, Cl.|pages = 141–167|url =http://resolver.sub.uni-goettingen.de/purl?GDZPPN002509180|year = 1933}}</ref> The highest concentration ever found was in the [[Hartley, Northumberland|Hartley]] coal ash with up to 1.6% of germanium.<ref name="Gold1" /><ref name="Gold2" /> The coal deposits near [[Xilinhaote]], [[Inner Mongolia]], contain an estimated 1600&nbsp;[[tonne]]s of germanium.<ref name="Holl" />

== Production ==
[[File:Renierit.JPG|left|thumb|[[Renierite]]|alt=A brown block of irregular shape and surface, about 6 cm in size.]]
About 118&nbsp;[[tonne]]s of germanium was produced in 2011 worldwide, mostly in China (80 t), Russia (5 t) and United States (3 t).<ref name="usgs" /> Germanium is recovered as a by-product from [[sphalerite]] [[zinc]] ores where it is concentrated in amounts of up to 0.3%,<ref>{{cite journal|doi=10.1016/0016-7037(85)90241-8|title=Germanium geochemistry and mineralogy|year=1985|author=Bernstein, L|journal=Geochimica et Cosmochimica Acta|volume=49|issue=11|page=2409|bibcode = 1985GeCoA..49.2409B }}</ref> especially from sediment-hosted, massive [[zinc|Zn]]–[[lead|Pb]]–[[copper|Cu]](–[[barium|Ba]]) deposits and carbonate-hosted Zn–Pb deposits. Figures for worldwide Ge reserves are not available, but in the US it is estimated at 450&nbsp;tonnes.<ref name="usgs" /> In 2007 35% of the demand was met by recycled germanium.<ref name="Holl" />

While it is produced mainly from [[sphalerite]], it is also found in [[silver]], [[lead]], and [[copper]] ores. Another source of germanium is [[fly ash]] of coal power plants which use coal from certain coal deposits with a large concentration of germanium. Russia and China used this as a source for germanium.<ref name="Naumov">{{cite journal|first = A. V.|last = Naumov|title = World market of germanium and its prospects|journal = Russian Journal of Non-Ferrous Metals|volume = 48|issue = 4|year = 2007|doi = 10.3103/S1067821207040049|pages =265–272}}</ref> Russia's deposits are located in the far east of the country on [[Sakhalin]] Island. The coal mines northeast of [[Vladivostok]] have also been used as a germanium source. The deposits in China are mainly located in the [[lignite]] mines near [[Lincang]], [[Yunnan]]; coal mines near [[Xilinhaote]], [[Inner Mongolia]] are also used.<ref name="Holl" />

<div style="float: right; margin: 5px;">
{|class="wikitable"
!Year !! Cost<br />([[United States dollar|$]]/kg)<ref><!--two sources in one here?-->{{cite journal |title = USGS Minerals Information |journal = U.S. Geological Survey Mineral Commodity Summaries| url=http://minerals.usgs.gov/minerals/pubs/commodity/germanium/index.html#mcs | publisher=U.S. Geological Survey| at = [http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220303.pdf January 2003], [http://minerals.usgs.gov/minerals/pubs/commodity/germanium/germamcs04.pdf January 2004], [http://minerals.usgs.gov/minerals/pubs/commodity/germanium/germamcs05.pdf January 2005], [http://minerals.usgs.gov/minerals/pubs/commodity/germanium/germamcs06.pdf January 2006], [http://minerals.usgs.gov/minerals/pubs/commodity/germanium/germamcs07.pdf January 2007],[http://minerals.usgs.gov/minerals/pubs/commodity/germanium/mcs-2010-germa.pdf January 2010] |isbn = 0-85934-039-2 |author = R.N. Soar |oclc = 16437701 |year = 1977}}</ref>
|-
|1999 || 1,400
|-
|2000 || 1,250
|-
|2001 || 890
|-
|2002 || 620
|-
|2003 || 380
|-
|2004 || 600
|-
|2005 || 660
|-
|2006 || 880
|-
|2007 || 1,240
|-
|2008 || 1,490
|-
|2009 || 950
|}
|}
</div>
The ore concentrates are mostly [[sulfide|sulfidic]]; they are converted to the [[oxide]]s by heating under air, in a process known as [[Roasting (metallurgy)|roasting]]:


==Gallery==
: GeS<sub>2</sub> + 3 O<sub>2</sub> → GeO<sub>2</sub> + 2 SO<sub>2</sub>
<gallery>

File:Illustration Geranium phaeum0.jpg|''[[Geranium phaeum]]'' - from Thomé ''Flora von Deutschland, Österreich und der Schweiz'' 1885
Part of the germanium ends up in the dust produced during this process, while the rest is converted to germanates which are leached together with the zinc from the cinder by sulfuric acid. After neutralization only the zinc stays in solution and the precipitate contains the germanium and other metals. After reducing the amount of zinc in the precipitate by the [[Waelz process]], the residing Waelz oxide is leached a second time. The [[germanium dioxide|dioxide]] is obtained as precipitate and converted with [[chlorine]] gas or hydrochloric acid to [[germanium tetrachloride]], which has a low boiling point and can be distilled off:<ref name="Naumov" />
File:geranium_platypetalum1.jpg|''[[Geranium platypetalum]]''

File:Geranium_sanguineum0.jpg|''[[Geranium sanguineum]]''
: GeO<sub>2</sub> + 4 HCl → GeCl<sub>4</sub> + 2 H<sub>2</sub>O
File:Geranium pratense (Meadow Cranesbill).jpg|''[[Geranium pratense]]'' (meadow cranesbill)
: GeO<sub>2</sub> + 2 Cl<sub>2</sub> → GeCl<sub>4</sub> + O<sub>2</sub>
File:Geranium-robertianum(Samen).jpg|''[[Geranium robertianum]]'' (herb robert)

File:GeraniumMaderense.jpg|''[[Geranium maderense]]''
Germanium tetrachloride is either hydrolyzed to the oxide (GeO<sub>2</sub>) or purified by fractional distillation and then hydrolyzed.<ref name="Naumov" />
File:wildgeranium.jpg|''[[Geranium maculatum]]''
The highly pure GeO<sub>2</sub> is now suitable for the production of germanium glass. The pure germanium oxide is reduced by the reaction with hydrogen to obtain germanium suitable for the infrared optics or semiconductor industry:
File:Starr 980718-1820 Geranium arboreum.jpg|[[Geranium arboreum]]

</gallery>
: GeO<sub>2</sub> + 2 H<sub>2</sub> → Ge + 2 H<sub>2</sub>O

The germanium for steel production and other industrial processes is normally reduced using carbon:<ref name="Moska">{{cite journal|journal = Minerals Engineering|year = 2004|pages = 393–402|doi = 10.1016/j.mineng.2003.11.014|title = Review of germanium processing worldwide|issue = 3|author = Moskalyk, R. R.|volume = 17}}</ref>

: GeO<sub>2</sub> + C → Ge + CO<sub>2</sub>

== Applications ==
[[File:Singlemode fibre structure.svg|thumb|right|A typical single-mode optical fiber. Germanium oxide is a [[dopant]] of the core silica (Item 1).<br />
1. Core 8&nbsp;µm<br />
2. Cladding 125&nbsp;µm<br />
3. Buffer 250&nbsp;µm<br />
4. Jacket 400&nbsp;µm|alt=A drawing of four concentric cylinders.]]
The major end uses for germanium in 2007, worldwide, were estimated to be: 35% for [[fiber-optic]] systems, 30% [[Infrared vision|infrared optics]], 15% for [[polymerization]] catalysts, and 15% for electronics and solar electric applications.<ref name="usgs" /> The remaining 5% went into other uses such as phosphors, metallurgy, and chemotherapy.<ref name="usgs" />

=== Optics ===
The most notable physical characteristics of [[Germanium dioxide|germania]] (GeO<sub>2</sub>) are its high [[refractive index|index of refraction]] and its low [[Dispersion (optics)|optical dispersion]]. These make it especially useful for [[wide-angle camera lens]]es, [[microscopy]], and for the core part of [[optical fiber]]s.<ref>{{cite journal|title=Infrared Detector Arrays for Astronomy|journal=Annual Review of Astronomy and Astrophysics|year = 2007 |doi = 10.1146/annurev.astro.44.051905.092436 |last = Rieke|first = G.H.| volume = 45|issue=1|page = 77|bibcode=2007ARA&A..45...77R}}</ref><ref name="Brown">{{cite web| url =http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220400.pdf|title = Germanium| first = Robert D.|last = Brown, Jr.| publisher = U.S. Geological Survey |format=PDF|year = 2000|accessdate = 2008-09-22}}</ref> It also replaced [[titanium dioxide|titania]] as the silica [[dopant]] for silica fiber, eliminating the need for subsequent heat treatment, which made the fibers brittle.<ref>{{cite web|url = http://www.sri.com/policy/csted/reports/sandt/techin2/chp3.html|title = Chapter III: Optical Fiber For Communications|publisher = Stanford Research Institute|accessdate = 2008-08-22}}{{dead link|date=April 2013}}</ref> At the end of 2002 the fiber optics industry accounted for 60% of the annual germanium use in the United States, but this use accounts for less than 10% of world wide consumption.<ref name="Brown" /> [[GeSbTe]] is a [[phase change material]] used for its optic properties, such as in [[DVD-RW|rewritable DVDs]].<ref>{{cite web|url=http://www.osta.org/technology/pdf/dvdqa.pdf|archiveurl=http://web.archive.org/web/20090419202545/http://www.osta.org/technology/pdf/dvdqa.pdf|archivedate=2009-04-19|title=Understanding Recordable & Rewritable DVD First Edition |format=PDF |accessdate=2008-09-22| publisher = Optical Storage Technology Association (OSTA)}}</ref>

Because germanium is transparent in the infrared it is a very important [[infrared]] optical material, that can be readily cut and polished into lenses and windows. It is especially used as the front optic in [[Thermographic camera|thermal imaging cameras]] working in the 8 to 14&nbsp;[[micrometre|micron]] [[wavelength]] range for passive thermal imaging and for hot-spot detection in military, [[night vision]] system in cars, and fire fighting applications.<ref name="Moska" /> It is therefore used in infrared [[spectroscope]]s and other optical equipment which require extremely sensitive [[Infrared photography|infrared detectors]].<ref name="Brown" /> The material has a very high [[refractive index]] (4.0) and so needs to be anti-reflection coated. Particularly, a very hard special antireflection coating of [[diamond-like carbon]] (DLC), refractive index 2.0, is a good match and produces a diamond-hard surface that can withstand much environmental rough treatment.<ref>{{cite journal|first = Alan H.|last =Lettington|doi = 10.1016/S0008-6223(98)00062-1|title = Applications of diamond-like carbon thin films|volume = 36|issue = 5–6|year = 1998|pages =555–560|journal = Carbon}}</ref><ref>{{cite journal|first = Michael N.|last = Gardos|author2=Bonnie L. Soriano |author3=Steven H. Propst |title = Study on correlating rain erosion resistance with sliding abrasion resistance of DLC on germanium|journal = Proc. SPIE|volume = 1325|page = 99|year = 1990|doi = 10.1117/12.22449|issue = Mechanical Properties|series = SPIE Proceedings|editor1-last = Feldman|editor1-first = Albert|editor2-last = Holly|editor2-first = Sandor}}</ref>

=== Electronics ===
[[Silicon-germanium]] alloys are rapidly becoming an important semiconductor material, for use in high-speed integrated circuits. Circuits utilizing the properties of Si-SiGe junctions can be much faster than those using silicon alone.<ref>{{cite journal|doi=10.1109/TED.2003.810484|title=SiGe HBT and BiCMOS technologies for optical transmission and wireless communication systems|year=2003 |last=Washio|first= K.|journal=IEEE Transactions on Electron Devices|volume=50|issue=3|page=656|bibcode = 2003ITED...50..656W }}</ref> Silicon-germanium is beginning to replace [[gallium arsenide]] (GaAs) in wireless communications devices.<ref name="usgs" /> The SiGe chips, with high-speed properties, can be made with low-cost, well-established production techniques of the [[silicon chip]] industry.<ref name="usgs" />

The recent rise in energy cost has improved the economics of [[solar panel]]s, a potential major new use of germanium.<ref name="usgs" /> Germanium is the substrate of the wafers for high-efficiency [[multijunction photovoltaic cell]]s for space applications.

Because germanium and [[gallium arsenide]] have very similar lattice constants, germanium substrates can be used to make gallium arsenide [[solar cell]]s.<ref>{{cite journal|doi=10.1002/pip.446|title=Space and terrestrial photovoltaics: synergy and diversity|year=2002|last=Bailey| first= Sheila G.|journal=Progress in Photovoltaics Research and Applications|volume=10|issue=6|page=399|last2=Raffaelle|first2=Ryne|last3=Emery|first3=Keith}}</ref> The [[Mars Exploration Rover]]s and several satellites use triple junction gallium arsenide on germanium cells.<ref>{{cite journal|doi = 10.1016/S0094-5765(02)00287-4| title = The performance of gallium arsenide/germanium solar cells at the Martian surface|year = 2004|first = D.|last = Crisp|coauthors = Pathare, A.; Ewell, R. C.| journal = Acta Astronautica |volume = 54|issue = 2|pages = 83–101|bibcode = 2004AcAau..54...83C }}</ref>

Germanium-on-insulator substrates are seen as a potential replacement for silicon on miniaturized chips.<ref name="usgs" /> Other uses in electronics include [[phosphor]]s in [[fluorescent lamp]]s,<ref name="lanl" /> and germanium-base solid-state light-emitting diodes (LEDs).<ref name="usgs" /> Germanium transistors are still used in some [[effects pedal]]s by musicians who wish to reproduce the distinctive tonal character of the [[Distortion (music)|"fuzz"-tone]] from the early [[rock and roll]] era, most notably the [[Fuzz Face|Dallas Arbiter Fuzz Face]].<ref>{{cite journal|author = Szweda, Roy|year = 2005|title = Germanium phoenix|journal = [[III-Vs Review]]|volume = 18|issue = 7|page = 55|doi = 10.1016/S0961-1290(05)71310-7}}</ref>

=== Other uses ===
[[File:Pet Flasche.JPG|thumb|upright|A [[polyethylene terephthalate|PET]] [[bottle]]|alt=Photo of a standard transparent plastic bottle.]]
Germanium dioxide is also used in [[catalyst]]s for [[polymerization]] in the production of [[polyethylene terephthalate]] (PET).<ref name="Thiele">{{cite journal|last = Thiele|first = Ulrich K.|year = 2001|title = The Current Status of Catalysis and Catalyst Development for the Industrial Process of Poly(ethylene terephthalate) Polycondensation|journal = International Journal of Polymeric Materials|volume = 50|issue = 3|pages = 387–394 |doi = 10.1080/00914030108035115}}</ref> The high brilliance of the produced polyester is especially used for PET bottles marketed in [[Japan]].<ref name="Thiele" /> However, in the United States, no germanium is used for polymerization catalysts.<ref name="usgs" /> Due to the similarity between silica (SiO<sub>2</sub>) and germanium dioxide (GeO<sub>2</sub>), the silica stationary phase in some [[gas chromatography]] columns can be replaced by GeO<sub>2</sub>.<ref>{{cite journal|title = Germania-Based, Sol-Gel Hybrid Organic-Inorganic Coatings for Capillary Microextraction and Gas Chromatography|last= Fang| first=Li|author2=Kulkarni, Sameer |author3=Alhooshani, Khalid |author4= Malik, Abdul |journal = Anal. Chem.|volume = 79|issue = 24|pages = 9441–9451|year = 2007|doi = 10.1021/ac071056f|pmid = 17994707}}</ref>

In recent years germanium has seen increasing use in precious metal alloys. In [[sterling silver]] alloys, for instance, it has been found to reduce [[firescale]], increase tarnish resistance, and increase the alloy's response to precipitation hardening. A tarnish-proof sterling silver alloy, trademarked [[Argentium sterling silver|Argentium]], contains 1.2% germanium.<ref name="usgs" />

High purity germanium single crystal detectors can precisely identify radiation sources—for example in airport security.<ref>{{cite web|title = Performance of Light-Weight, Battery-Operated, High Purity Germanium Detectors for Field Use|first = Ronald|last = Keyser|coauthors = Twomey, Timothy; Upp, Daniel|url = http://www.ortec-online.com/papers/inmm_2003_keyser.pdf |format=PDF| accessdate = 2008-09-06|publisher = Oak Ridge Technical Enterprise Corporation (ORTEC)|archiveurl = http://web.archive.org/web/20071026162911/http://www.ortec-online.com/papers/inmm_2003_keyser.pdf |archivedate = October 26, 2007|deadurl=yes}}</ref> Germanium is useful for [[Crystal monochromator|monochromators]] for [[beamline]]s used in [[single crystal]] [[neutron scattering]] and [[Synchrotron light|synchrotron X-ray]] diffraction. The reflectivity has advantages over silicon in neutron and [[High energy X-rays|high energy X-ray]] applications.<ref>{{cite journal |doi=10.1142/S0218301396000062 |year=1996 |author=Ahmed, F. U. |journal=International Journal of Modern Physics E |volume=5 |issue=1 |page=131|title = Optimization of Germanium for Neutron Diffractometers|bibcode = 1996IJMPE...5..131A |last2=Yunus |first2=S.M. |last3=Kamal |first3=I. |last4=Begum |first4=S. |last5=Khan |first5=Aysha A. |last6=Ahsan |first6=M.H. |last7=Ahmad |first7=A.A.Z. }}</ref> Crystals of high purity germanium are used in [[Germanium detector|detectors]] for [[gamma spectroscopy]] and the search for [[dark matter]].<ref>{{cite journal |doi=10.1016/j.nuclphysa.2005.02.155 |title=Astrophysical constraints from gamma-ray spectroscopy |year=2006 |last=Diehl|first= R. |journal=Nuclear Physics A |volume=777 |page=70 |last2=Prantzos |first2=N |last3=Vonballmoos |first3=P|arxiv = astro-ph/0502324 |bibcode = 2006NuPhA.777...70D }}</ref> The slightly radioactive Germanium 76, which decays only through double-beta decay, is used to study that process (for example, in the ongoing [[MAJORANA|MAJORANA demonstrator]] experiment).

=== Inorganic germanium and health hazard ===
Inorganic germanium and organic germanium are different chemical compounds of germanium and their properties are different. Inorganic germanium will accumulate inside the body and will impose health hazards after consumed. Organic germanium is reported to be potentially beneficial for health.<ref name="Gerber 1997 141–146">{{cite journal|first = G.B.|last = Gerber|author2=Léonard, A.| year = 1997|title = Mutagenicity, carcinogenicity and teratogenicity of germanium compounds|journal = Regulatory Toxicology and Pharmacology|volume = 387|issue = 3|pages = 141–146|doi = 10.1016/S1383-5742(97)00034-3}}</ref>

Germanium is not thought to be essential to the health of plants or animals. Germanium in the environment has little or no health impact. This is primarily because it usually occurs only as a trace element in ores and [[carbon]]aceous materials, and is used in very small quantities that are not likely to be ingested, in its various industrial and electronic applications.<ref name="usgs" /> For similar reasons, germanium in end-uses has little impact on the environment as a biohazard. Some reactive intermediate compounds of germanium are poisonous (see precautions, below).<ref name="Brown Jr">{{cite report|url=http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220798.pdf|format=PDF|publisher=US Geological Surveys|accessdate=2008-09-09| title = Commodity Survey:Germanium|first = Robert D.|last = Brown Jr.}}</ref>

As early as 1922, doctors in the United States used the inorganic form of germanium to treat patients with [[anemia]].<ref name="Brown Jr"/> It was used in other forms of treatments, such as a purported immune system booster, but its efficiency has been dubious. Its role in [[cancer treatment]]s has been debated, with the American Cancer Society contending that no anticancer effects have been demonstrated.<ref name="Germanium">{{cite web|url = http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Germanium.asp|title = Germanium|publisher = American Cancer Society| accessdate = 2008-08-31}}</ref><ref>{{cite journal|first = Milan|last = Slavik|coauthors = Blanc, Oscar; Davis, Joan|title = Spirogermanium: A new investigational drug of novel structure and lack of bone marrow toxicity|journal = Investigational New Drugs|volume = 1|issue = 3|year = 1983|doi = 10.1007/BF00208894|pages = 225–234|pmid = 6678870}}</ref> [[U.S. Food and Drug Administration]] research has concluded that inorganic germanium, when used as a [[nutritional supplement]], "presents potential human [[health hazard]]".<ref name="toxic">{{cite journal|last = Tao|first = S. H.|author2=Bolger, P. M.|date=June 1997|title = Hazard Assessment of Germanium Supplements|journal = [[Regulatory Toxicology and Pharmacology]]|volume = 25|issue = 3|pages = 211–219|doi = 10.1006/rtph.1997.1098|pmid = 9237323}}</ref>

Certain germanium compounds are available in low dose in the U.S. as nonprescription dietary "supplements" in oral capsules or tablets. Other germanium compounds have been administered by alternative medical practitioners as non-FDA-allowed injectable solutions. Soluble inorganic forms of germanium used at first, notably the citrate-lactate salt, led to a number of cases of [[renal]] dysfunction, [[hepatic steatosis]] and peripheral [[neuropathy]] in individuals using them on a chronic basis. Plasma and urine germanium concentrations in these individuals, several of whom died, were several orders of magnitude greater than [[endogenous]] levels. A more recent organic form, beta-carboxyethylgermanium sesquioxide ([[propagermanium]]), has not exhibited the same spectrum of toxic effects.<ref>{{cite book|author=Baselt, R. |title=Disposition of Toxic Drugs and Chemicals in Man|edition=8|publisher=Biomedical Publications|place=Foster City, CA|year=2008|pages=693–694}}</ref>

Certain compounds of germanium have low toxicity to [[mammal]]s, but have toxic effects against certain [[bacterium|bacteria]].<ref name="nbb">{{cite book| last = Emsley| first = John| title = Nature's Building Blocks| publisher = Oxford University Press| year = 2001| location = Oxford| pages = 506–510| isbn = 0-19-850341-5}}</ref>

== Precautions for chemically reactive germanium compounds ==
Some of germanium's artificially-produced compounds are quite reactive and present an immediate hazard to human health on exposure. For example, [[Germanium tetrachloride|germanium chloride]] and [[germane]] (GeH<sub>4</sub>) are a liquid and gas, respectively, that can be very irritating to the eyes, skin, lungs, and throat.<ref name="Gerber 1997 141–146"/>


== See also ==
== See also ==
{{wikispecies|Geranium}}
* [[Transistor]]
{{commons|Geranium}}
* [[Vitrain]]
* [[List of cranesbill species]]
{{Subject bar
* ''[[Pelargonium graveolens]]'', from which ''Geranium'' essential oil is distilled
|portal=Chemistry
|book1=Germanium
|book2=Period 4 elements
|book3=Carbon group
|book4=Chemical elements (sorted&nbsp;alphabetically)
|book5=Chemical elements (sorted by number)
|commons=y
|wikt=y
|wikt-search=germanium
}}

== Footnotes ==
{{Reflist|group=n}}

== References ==
{{Reflist|30em}}


==References==
== External links ==
{{Reflist}}
* [http://www.periodicvideos.com/videos/032.htm Germanium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [http://www.rjb.csic.es/Geranium/publication/geranium_n_america_perennials.pdf Genus ''Geranium'' in North America: the Perennials]


==External links==
{{compact periodic table}}
* [http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=29104 ITIS list of Geranium species]
{{Chemical elements named after places}}
* [http://www.geranium.es/ Geranium Taxonomic Information System]
{{Germanium compounds}}
* [http://www.conoce3000.com/html/espaniol/Galeria.php?Album=10 Photograph of some Geranium]
{{featured article}}


[[Category:Germanium| ]]
[[Category:Flowers]]
[[Category:Chemical elements]]
[[Category:Geranium| ]]
[[Category:Infrared sensor materials]]
[[Category:Garden plants]]
[[Category:Metalloids]]
[[Category:Optical materials]]
[[Category:Semiconductor materials]]

Revision as of 01:10, 21 October 2014

This article is about the botanical genus called Geranium. For the summer bedding plants often called "geranium", see Pelargonium. For other uses, see Geranium (disambiguation).
Not to be confused with germanium.

Geranium
Geranium dissectum
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Rosids
Order:
Geraniales
Family:
Geraniaceae
Genus:
Geranium

Species

See list.

Geranium is a genus of 422 species of flowering annual, biennial, and perennial plants that are commonly known as the cranesbills. They are found throughout the temperate regions of the world and the mountains of the tropics, but mostly in the eastern part of the Mediterranean region. The long, palmately cleft leaves are broadly circular in form. The flowers have five petals and are coloured white, pink, purple or blue, often with distinctive veining. Geraniums will grow in any soil as long as it is not waterlogged. Propagation is by semiripe cuttings in summer, by seed, or by division in autumn or spring.

The genus name is derived from the Greek γέρανος (géranos) or γερανός (geranós) ‘crane’. The English name ‘cranesbill’ derives from the appearance of the fruit capsule of some of the species. Species in the Geranium genus have a distinctive mechanism for seed dispersal. This consists of a beak-like column which springs open when ripe and casts the seeds some distance. The fruit capsule consists of five cells, each containing one seed, joined to a column produced from the centre of the old flower. The common name ‘cranesbill’ comes from the shape of the unsprung column, which in some species is long and looks like the bill of a crane. However, many species in this genus do not have a long beak-like column.

Geraniums are eaten by the larvae of some Lepidoptera species including brown-tail and mouse moth.

The species Geranium viscosissimum (sticky geranium) is considered to be protocarnivorous.

Confusion with pelargoniums

Showing the "bill" and seed dispersal mechanism of Geranium pratense

Confusingly, "geranium" is also the common name of members of the genus Pelargonium (sometimes known as 'storksbill'), which are also in the Geraniaceae family. These are generally half-hardy plants which are either grown from seed every year, or offered as bedding in spring and discarded after flowering. Linnaeus originally included all the species in one genus, Geranium, but they were later separated into two genera by Charles L’Héritier in 1789. Other former members of the genus are now classified in genus Erodium, including the plants known as filarees in North America.

The term "hardy geranium" is often applied to geraniums to distinguish them from the pelargoniums. However, not all geranium species are winter-hardy (see below).

Structure

The shape of the flowers offers one way of distinguishing between the two genera Geranium and Pelargonium. Geranium flowers have five very similar petals, and are thus radially symmetrical (actinomorphic), whereas pelargonium flowers have two upper petals which are different from the three lower petals, so the flowers have a single plane of symmetry (zygomorphic).

Cultivation

A number of geranium species are cultivated for horticultural use and for pharmaceutical products. Some of the more commonly grown species include:

All the above species are perennials and generally winter-hardy plants, grown for their attractive flowers and foliage. They are long-lived and most have a mounding habit, with palmately lobed foliage. Some species have spreading rhizomes. They are normally grown in part shade to full sun, in well-draining but moisture retentive soils, rich in humus.[1] Other perennial species grown for their flowers and foliage include: G. argenteum, G. eriostemon, G. farreri, G. nodosum, G. procurrens, G. pylzowianum, G. renardii, G. traversii, G. tuberosum, G. versicolor, G. wallichianum and G. wlassovianum. Some of these are not winter-hardy in cold areas and are grown in specialized gardens like rock gardens.[2] Geranium 'Johnson's Blue' is a hybrid between G. himalayense (southwestern China), with G. pratense (European meadow cranesbill).[3]

The following hybrid cultivars have gained the Royal Horticultural Society's Award of Garden Merit (other cultivars are dealt with under their species name - see above).

  • 'Ann Folkard'[4]
  • 'Dilys'[5]
  • 'Johnson's Blue'[6]
  • 'Mavis Simpson'[7]
  • 'Orion'[8]
  • 'Rozanne'[9]
  • 'A. T. Johnson' (G. × oxonianum)[10]
  • 'Wargrave pink' (G. × oxonianum)[11]

See also

Wikispecies has information related to Geranium.
Wikimedia Commons has media related to Geranium.

References

  1. ^ Phillips, Ellen; Colston Burrell, C. (1993), Rodale's illustrated encyclopedia of perennials, Emmaus, Pa.: Rodale Press, pp. 373–76, ISBN 0-87596-570-9
  2. ^ Jelitto, Leo; Schacht, Wilhelm; Epp, Translated by Michael E.; John Philip Baumgardt, Technical Editor (1990), Hardy herbaceous perennials, vol. 1, Portland, Or.: Timber Press, pp. 260–64, ISBN 0-88192-159-9 {{citation}}: |first4= has generic name (help)
  3. ^ "Paghat's Garden". Paghat.com. Retrieved 2013-09-17.
  4. ^ "RHS Plant Selector Geranium 'Ann Folkard' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  5. ^ "RHS Plant Selector Geranium 'Dilys' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  6. ^ "RHS Plant Selector Geranium 'Johnson's Blue' / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  7. ^ "RHS Plant Selector Geranium 'Mavis Simpson' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  8. ^ "RHS Plant Selector Geranium 'Orion' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  9. ^ "RHS Plant Selector Geranium ROZANNE 'Gerwat' PBR AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  10. ^ "RHS Plant Selector Geranium × oxonianum 'A.T. Johnson' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
  11. ^ "RHS Plant Selector Results / RHS Gardening". Apps.rhs.org.uk. Retrieved 2013-09-17.
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Geranium&oldid=630453853"