Difference between revisions of "Peridiscaceae"

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{{taxobox
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#redirect [[:Category:Peridiscaceae]]
|name = Peridiscaceae
 
|regnum = [[Plant]]ae
 
|unranked_divisio = [[Angiosperms]]
 
|unranked_classis = [[Eudicots]]
 
|unranked_ordo = [[Core eudicots]]
 
|ordo = [[Saxifragales]]
 
|familia = '''Peridiscaceae'''
 
|familia_authority = [[João Geraldo Kuhlmann|Kuhlm.]]<ref name=APGIII2009>{{Cite journal |last=Angiosperm Phylogeny Group |year=2009 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III |journal=Botanical Journal of the Linnean Society |volume=161 |issue=2 |pages=105–121 |url=http://onlinelibrary.wiley.com/doi/10.1046/j.1095-8339.2003.t01-1-00158.x/pdf | format= PDF |accessdate=2013-07-06 |doi=10.1111/j.1095-8339.2009.00996.x }}</ref>
 
|subdivision_ranks = [[Genus|Genera]]
 
|subdivision =
 
*''[[Medusandra]]'' <small>[[John Patrick Micklethwait Brenan|Brenan]]</small>
 
*''[[Peridiscus]]'' <small>[[George Bentham|Benth.]]</small>
 
*''[[Soyauxia]]'' <small>[[Daniel Oliver|Oliv.]]</small>
 
*''[[Whittonia]]'' <small>[[Noel Yvri Sandwith|Sandwith]]</small>
 
}}
 
 
 
'''Peridiscaceae''' is a [[Family (biology)|family]] of [[flowering plant]]s in the [[Order (biology)|order]] [[Saxifragales]].<ref name="peridiscaceae">Peter F. Stevens. 2001 onwards. "Peridiscaceae". At: Angiosperm Phylogeny Website At: Missouri Botanical Garden Website. (see ''External links'' below).</ref> Four [[genera]] comprise this family: ''[[Medusandra]], [[Soyauxia]], [[Peridiscus]]'', and ''[[Whittonia]]''.,<ref name="wurdack2009">Kenneth J. Wurdack and Charles C. Davis. 2009. "Malpighiales phylogenetics: Gaining ground on one of the most recalcitrant clades in the angiosperm tree of life." ''American Journal of Botany'' '''96'''(8):1551-1570.</ref> with a total of 12 known species.<ref name="Christenhusz-Byng2016">{{cite journal |author1=Christenhusz, M. J. M. |author2=Byng, J. W.  |lastauthoramp=yes | year = 2016 | title = The number of known plants species in the world and its annual increase | journal = Phytotaxa | volume = 261 | pages = 201–217 | url = http://biotaxa.org/Phytotaxa/article/download/phytotaxa.261.3.1/20598 | doi = 10.11646/phytotaxa.261.3.1 | issue = 3 | publisher = Magnolia Press }}</ref> It has a [[disjunct distribution]], with ''Peridiscus'' occurring in [[Venezuela]] and northern [[Brazil]], ''Whittonia'' in [[Guyana]],<ref name="bayer2007">Clemens Bayer. 2007. "Peridiscaceae" pages 297-300. In:  Klaus Kubitski (editor). ''The Families and Genera of Vascular Plants'' volume IX. Springer-Verlag: Berlin;Heidelberg, Germany. {{ISBN|978-3-540-32214-6}}</ref> ''Medusandra'' in [[Cameroon]], and ''Soyauxia'' in [[Tropics|tropical]] [[West Africa]].<ref name="heywood2007">Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. (2007). {{ISBN|1-55407-206-9}}</ref> ''Whittonia'' is possibly [[extinct]], being known from only one [[Biological specimen|specimen]] collected below [[Kaieteur Falls]] in Guyana. An attempt to rediscover it in 2006 was not successful.<ref name="wurdack2009"/>
 
 
 
The largest genus is ''Soyauxia'', with about seven species. ''Medusandra'' has two species. ''Peridiscus'' and ''Whittonia'' each contain one species. The Peridiscaceae are small [[tree]]s or erect [[shrub]]s of wet tropical [[forest]]s.
 
 
 
It was not until 2009 that all four of the genera were united into a single family.<ref name="wurdack2009"/> ''Peridiscus'' and ''Whittonia'' are clearly close relatives. This pair, and the other two genera have long been considered anomalous, being variously classified by different authors.
 
 
 
== Description ==
 
The following description was created by combining descriptions of ''Medusandra'' and ''Peridiscus'' by [[John Hutchinson (botanist)|John Hutchinson]] <ref name="hutchinson1973">John Hutchinson. ''The Families of Flowering Plants, Third Edition (1973)''. Oxford University Press: London.</ref>  with descriptions of ''Soyauxia'', ''Peridiscus'', and ''Whittonia'' by Clemens Bayer.<ref name="bayer2007"/>
 
 
 
Peridiscaceae are small [[tree]]s or erect [[shrub]]s. The leaves are [[Stipule|stipulate]], [[Leaf#Arrangement on the stem|alternate]], and [[Leaf#Divisions of the lamina (blade)|simple]], with margins that are [[Leaf shape|entire]] or remotely [[Leaf#Margins (edge)|crenulate]] (''Medusandra''). The [[Petiole (botany)|petiole]] is [[Pulvinus|pulvinate]], at its [[Glossary of botanical terms#A|apex]], sometimes obscurely so. The stipules are in the [[Glossary of botanical terms#A|axil]]s of the leaves, sometimes enclosing an axillary [[bud]].
 
 
 
The [[inflorescence]] is a cluster of axillary [[raceme]]s or [[Raceme|spike]]s, the clusters often being reduced to a pair of racemes or to a single raceme. The [[flower]]s are bisexual and [[Floral symmetry|actinomorphic]]. The [[sepal]]s are 4 to 7 in number, and [[Glossary of botanical terms#F|free]], that is, separate from each other. ''Medusandra'' and ''Soyauxia'' have five [[petal]]s. ''Peridiscus'' and ''Whittonia'' have none.
 
 
 
''Medusandra'' lacks a [[nectar]]y disk and has five [[stamen]]s, inserted opposite the petals, and alternating with five long, hairy [[staminode]]s. In the others, the stamens are [[Glossary of botanical terms#N|numerous]] and arranged in a ring around the nectary disk. The [[anther]]s are tetra[[theca]]l in ''Medusandra'' and ''Soyauxia''; bithecal in ''Peridiscus'' and ''Whittonia''.
 
 
 
The [[perianth]] parts are attached below the [[Ovary (plants)|ovary]]. The ovary is therefore [[superior ovary|superior]], but appears half-inferior in ''Peridiscus'' because the ovary is embedded in the large, fleshy disk. The [[gynoecium]] consists of three or four [[carpel]]s, united to form a [[Locule|unilocular]] ovary. The [[Placentation#Placentation in plants|placentation]] is apical, with two [[ovule]]s at the apex of each carpel. The ovary has a central column in ''Medusandra'' and ''Soyauxia''. Each carpel bears a [[Glossary of botanical terms#S|stylulus]] and these are well separated at the apex of the ovary.
 
 
 
The [[fruit]] is one-[[seed]]ed; a [[Capsule (fruit)|capsule]] in ''Medusandra'' and ''Soyauxia''; a [[drupe]] in ''Peridiscus'' and ''Whittonia''.
 
 
 
== History ==
 
[[George Bentham]] established the genus ''Peridiscus'' in 1862, naming its only species ''Peridiscus lucidus''. He placed it in a group which he called "Tribus Flacourtieae" and which later would be known as the family [[Flacourtiaceae]].<ref name="bentham&hooker">George Bentham and Joseph Dalton Hooker. 1862. ''Genera Plantarum'' volume 1, part 1, page 127. A. Black, William Pamplin, Lovell Reeve & Co., Williams & Norgate: London, England. (see ''External links'' below).</ref> Bentham wrote no [[etymology]] for this name, but it is generally believed that the name refers to the fact that the stamens are attached along the outer edge of the nectary disk.<ref name="quattrocchipage2010">Umberto Quattrocchi. 2000. ''CRC World Dictionary of Plant Names''. volume III, page 2010. CRC Press: Baton Rouge, New York, London, Washington DC. {{ISBN|978-0-8493-2673-8}}. (see ''External links'' below)</ref>
 
 
 
[[Daniel Oliver]] established the genus ''Soyauxia'' in 1880 for ''[[Soyauxia gabonensis]]'', placing it in the family [[Passifloraceae]].<ref name="hooker1880">Joseph Dalton Hooker. 1880. ''Hooker's Icones Plantarum'' volume XIV (volume IV of the third series):page 73 and plate 1393. (see ''External links'' below).</ref> He named it for the [[Germans|German]] botanist and plant collector [[Hermann Soyaux]],<ref name="quattrocchipage2521">Umberto Quattrocchi. 2000. ''CRC World Dictionary of Plant Names''. volume IV, page 2521. CRC Press: Baton Rouge, New York, London, Washington DC. {{ISBN|978-0-8493-2677-6}}.</ref> saying "Mons. Soyaux, now settled in the Gaboon, well deserves that his name should be associated with one of his interesting discoveries in that region".<ref name="hooker1880"/>
 
 
 
The family Flacourtiaceae was, as [[Hermann Otto Sleumer|Hermann Sleumer]] said, a fiction,<ref name="miller1975">Regis B. Miller (1975). "Systematic anatomy of the xylem and comments on the relationships of Flacourtiaceae". ''Journal of the Arnold Arboretum'' '''56'''(1):79.</ref><ref name="chase2002">Mark W. Chase, Sue Zmarzty, M. Dolores Lledó, Kenneth J. Wurdack, Susan M. Swensen, and Michael F. Fay. 2002. "When in doubt, put it in Flacourtiaceae: a molecular phylogenetic analysis based on plastid ''rbcL'' DNA sequences." ''Kew Bulletin'' '''57'''(1):141-181.</ref>  and ''Peridiscus'' was, from the outset, one of its most doubtful members.<ref name="bayer2007"/><ref name="hutchinson1973"/> Recognizing its distinctiveness, [[João Geraldo Kuhlmann|João Kuhlmann]] [[Segregate (taxonomy)|segregated]] it into its own family in 1947.<ref name="kuhlmann1947">João G. Kuhlmann. 1947. "Peridiscaceae (Kuhlmann)". ''Arquivos do Serviço Florestal'' 3(1):3-7.</ref>
 
 
 
In 1952, [[John Patrick Micklethwait Brenan|John Brenan]] named and described ''Medusandra'', erecting a new family, [[Medusandraceae]] to accommodate it.<ref name="brenan1952">John P.M. Brenan. 1952. "Plants of the Cambridge Expedition, 1947-1948: II. A new order of flowering plants from the British Cameroons". ''Kew Bulletin'' '''7''':227-236.</ref> In 1953, Brenan transferred ''Soyauxia'' from Passifloraceae to Medusandraceae,<ref name="brenan1953">John P.M. Brenan. 1953. "''Soyauxia'', a second genus of Medusandraceae". ''Kew Bulletin'' '''8''':507-511.</ref> but few others agreed with his classification. In 1954, [[John Hutchinson (botanist)|John Hutchinson]] and [[John McEwen Dalziel]] followed Brenan's treatment in the second edition of their ''Flora of West Tropical Africa''. Hutchinson, however, soon recanted, explaining in some detail why he thought that ''Medusandra'' and ''Soyauxia'' were not related.<ref name="hutchinson1973"/>
 
 
 
In 1962, Noel Y. Sandwith named and described ''Whittonia''.<ref name="sandwith1962">Noel Y. Sandwith. 1962. "Contributions to the flora of tropical America: LXIX. A new genus of Peridiscaceae". ''Kew Bulletin'' '''15''':467-471.</ref> In an accompanying article, Charles Russell Metcalfe discussed its close relationship to ''Peridiscus''. For four decades thereafter, Peridiscaceae was viewed as a family of uncertain taxonomic position, containing two genera.
 
 
 
In the year 2000, a [[DNA sequence]] for the [[RuBisCO|''rbcL'']] [[gene]] of ''Whittonia'' was produced and used in a [[molecular phylogenetic]] study of the [[eudicots]].<ref name="savolainen2000">Vincent Savolainen, Michael F. Fay, Dirk C. Albach, Anders Backlund, Michelle van der Bank, Kenneth M. Cameron, S.A. Johnson, M. Dolores Lledo, Jean-Christophe Pintaud, Martyn P. Powell, Mary Clare Sheahan, [[Douglas E. Soltis]], [[Pamela S. Soltis]], Peter Weston, W. Mark Whitten, Kenneth J. Wurdack and [[Mark W. Chase]]. 2000. "Phylogeny of the eudicots: a nearly complete familial analysis based on ''rbcL'' gene sequences". ''Kew Bulletin'' '''55'''(2):257-309.</ref> This study placed Peridiscaceae in a [[clade]] with [[Elatinaceae]] and [[Malpighiaceae]], a very surprising and unexpected result. On the basis of this [[phylogeny]], the [[Angiosperm Phylogeny Group]] placed Peridiscaceae in [[Malpighiales]] when they published the [[APG II system]] of [[History of plant systematics|plant classification]] in 2003.<ref name="apgii">The Angiosperm Phylogeny Group. 2003. "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II". ''Botanical Journal of the Linnean Society'' '''141'''(4):399-436.</ref> It was soon found that the ''rbcL'' sequence for ''Whittonia'' was a [[Fusion protein|chimera]], formed by [[DNA]] from unidentified plants that had contaminated the [[Sample (material)|sample]].<ref name="davis2004">{{cite journal|author1=Davis, C. C.  |author2=Chase, M. W. |authorlink2=Mark Wayne Chase |lastauthoramp=yes |year = 2004|title = Elatinaceae are sister to Malpighiaceae; Peridiscaceae belong to Saxifragales.|journal = American Journal of Botany|volume = 91|pages = 262–273 | url = http://www.amjbot.org/cgi/reprint/91/2/262 | format = [[PDF]]| accessdate = 2007-07-01|doi = 10.3732/ajb.91.2.262 | issue=2 | pmid=21653382}}</ref> No subsequent attempt to extract DNA from ''Whittonia'' has been made.
 
 
 
In 2004, using DNA from ''Peridiscus'', it was shown that Elatinaceae and Malpighiaceae are indeed [[Cladistics#Subtrees are clades|sister]] families and that Peridiscaceae belong to Saxifragales.<ref name="davis2004"/> ''Medusandra'' and ''Soyauxia'', meanwhile, were listed in APG II in an appendix entitled "TAXA OF UNCERTAIN POSITION".<ref name="apgii"/>
 
 
 
DNA from ''Soyauxia'' was eventually obtained, and in 2007, it was shown that ''Soyauxia'' is most closely related to ''Peridiscus'' and, presumably, ''Whittonia''.<ref name="soltis2007">[[Douglas E. Soltis]], Joshua W. Clayton, Charles C. Davis, Matthew A. Gitzendanner, Martin Cheek, Vincent Savolainen, André M. Amorim, and [[Pamela S. Soltis]]. 2007. "Monophyly and relationships of the enigmatic family Peridiscaceae". ''Taxon'' '''56'''(1):65-73.</ref> Since this result has a good [[Plant morphology|morphological]] basis, ''Soyauxia'' was duly transferred to Peridiscaceae. This study also found strong statistical support for the inclusion of Peridiscaceae in Saxifragales, but no strong support for any particular position within that order.<ref name="soltis2007"/>
 
 
 
In 2008, in a study employing a large amount of [[chloroplast]] DNA data, as well as some [[mitochondrial]] and [[Cell nucleus|nuclear]] DNA, it was shown that Peridiscaceae is sister to the rest of Saxifragales.<ref name="jian2008">Shuguang Jian, [[Pamela S. Soltis]], Matthew A. Gitzendanner, Michael J. Moore, Ruiqi Li, Tory A. Hendry, Yin-Long Qiu, Amit Dhingra, Charles D. Bell, and [[Douglas E. Soltis]]. 2008. "Resolving an Ancient, Rapid Radiation in Saxifragales". ''Systematic Biology'' '''57'''(1):38-57.</ref>
 
 
 
It had been suspected that ''Medusandra'' might belong somewhere in Malpighiales, but a phylogeny of that order, generated in 2009, placed ''Medusandra'' in Saxifragales. The authors had included ''Medusandra'' and a few other members of Saxifragales in their [[Outgroup (cladistics)|outgroup]], finding strong support for a clade of [''Medusandra'' + (''Soyauxia'' + ''Peridiscus'')].<ref name="wurdack2009"/> When the [[APG III system]] was published in October 2009, Peridiscaceae was [[Circumscription (taxonomy)|expanded]] to include ''Medusandra'' and ''Soyauxia''.<ref name=APGIII2009/> John Brenan, 57 years before, had been prescient in his perception of a relationship between ''Medusandra'' and ''Soyauxia''.
 
 
 
== Phylogeny ==
 
The [[phylogeny]] is diagrammed as a [[phylogenetic tree]] below. The relationships shown are from Wurdack and Davis (2009) <ref name="wurdack2009"/> except for the position of ''Whittonia'', for which no DNA sequences are known. ''Peridiscus'' and ''Whittonia'' are undoubtedly [[sister taxon|sister]] [[Taxon|taxa]] due to their many shared morphological characters.
 
 
 
{{clade | style=font-size:100%;line-height:120%
 
|label1='''Peridiscaceae'''&nbsp;
 
|1={{clade
 
  |1=''[[Medusandra]]''
 
  |2={{clade
 
      |1=''[[Soyauxia]]''
 
      |2={{clade
 
        |1=''[[Peridiscus]]''
 
        |2=''[[Whittonia]]''
 
        }}
 
      }}
 
  }}
 
}}
 
 
 
==References==
 
{{reflist}}
 
 
 
==External links==
 
* [http://www.mobot.org/MOBOT/Research/APweb/orders/saxifragalesweb.htm#Peridiscaceae Peridiscaceae] At: [http://www.mobot.org/MOBOT/Research/APweb/welcome.html Angiosperm Phylogeny Website] At: [http://www.mobot.org Missoure Botanical Garden Website]
 
* [https://books.google.com/books?id=kaN-hLL-3qEC&printsec=frontcover&dq=CRC+World+Dictionary+of+Plant+Names&hl=en&ei=ZE4_TdjGDo7EsAPp8ZSUBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEEQ6AEwAA#v=onepage&q&f=false CRC World Dictionary of Plant Names: M-Q] At: [https://books.google.com/books?id=jz8AAAAAQAAJ&printsec=frontcover&source=gbs_v2_summary_r&cad=0#v=onepage&q=&f=false Hooker's Icones Plantarum]
 
* APG III {{DOI| 10.1111/j.1095-8339.2009.00996.x}}
 
* [http://delta-intkey.com/angio/www/peridisc.htm Peridiscaceae] in L. Watson and M.J. Dallwitz (1992 onwards). [http://delta-intkey.com/angio/ The families of flowering plants]: descriptions, illustrations, identification, information retrieval.
 
 
 
[[Category:Peridiscaceae| ]]
 
[[Category:Saxifragales families]]
 

Latest revision as of 19:41, 8 September 2017