Peridiscaceae is a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s in the
order Saxifragales
The Saxifragales (saxifrages) are an order of flowering plants (Angiosperms). They are an extremely diverse group of plants which include trees, shrubs, perennial herbs, succulent and aquatic plants. The degree of diversity in terms of vege ...
.
[Peter F. Stevens. 2001 onwards. "Peridiscaceae". At: Angiosperm Phylogeny Website At: Missouri Botanical Garden Website. (see ''External links'' below).] Four
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
comprise this family: ''
Medusandra
''Medusandra'' is a genus of flowering plants in the family Peridiscaceae."Peridiscaceae" At: Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. At: Missouri Botanical Garden Website. (see external links below) It has two species, '' ...
,
Soyauxia
''Soyauxia'' is a genus of flowering plants in the family Peridiscaceae.Clemens Bayer. 2007. "Peridiscaceae" pages 297-300. In: Klaus Kubitski (editor). ''The Families and Genera of Vascular Plants'' volume IX. Springer-Verlag: Berlin;Heidelberg ...
,
Peridiscus'', and ''
Whittonia''.,
[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.] with a total of 12 known species.
It has a
disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but considerably separated from each other geographically. The causes are varied and might demonstrate either the expansion or contraction of a s ...
, with ''Peridiscus'' occurring in
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
and northern
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, ''Whittonia'' in
Guyana
Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...
,
[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. ] ''Medusandra'' in
Cameroon
Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
, and ''Soyauxia'' in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
West Africa
West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...
.
[Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. (2007). ] ''Whittonia'' is possibly
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
, being known from only one
specimen
Specimen may refer to:
Science and technology
* Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount
* Biological specimen or biospecimen, an organic specimen held by a biorepository ...
collected below
Kaieteur Falls
Kaieteur is the world's largest single drop waterfall. Located on the Potaro River in the Kaieteur National Park, it sits in a section of the Amazon rainforest included in the Potaro-Siparuni region of Guyana. It is 226 metres (741 ft) ...
in Guyana. In 2006, archeologists attempted to rediscover it, however, it proved unsuccessful.
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
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s or erect
shrub
A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
s of wet tropical
forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s.
It was not until 2009 that all four of the genera were united into a single family.
''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[John Hutchinson. ''The Families of Flowering Plants, Third Edition (1973)''. Oxford University Press: London.] with descriptions of ''Soyauxia'', ''Peridiscus'', and ''Whittonia'' by Clemens Bayer.
Peridiscaceae are small
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s or erect
shrub
A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
s. The leaves are
stipulate,
alternate
Alternative or alternate may refer to:
Arts, entertainment and media
* Alternative (''Kamen Rider''), a character in the Japanese TV series ''Kamen Rider Ryuki''
* ''The Alternative'' (film), a 1978 Australian television film
* ''The Alternative ...
, and
simple
Simple or SIMPLE may refer to:
*Simplicity, the state or quality of being simple
Arts and entertainment
* ''Simple'' (album), by Andy Yorke, 2008, and its title track
* "Simple" (Florida Georgia Line song), 2018
* "Simple", a song by Johnn ...
, with margins that are
entire
Entire may refer to:
* Entire function, a function that is holomorphic on the whole complex plane
* Entire (animal), an indication that an animal is not neutered
* Entire (botany)
This glossary of botanical terms is a list of definitions of ...
or remotely
crenulate
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...
(''Medusandra''). The
petiole is
pulvinate, at its
apex
The apex is the highest point of something. The word may also refer to:
Arts and media Fictional entities
* Apex (comics), a teenaged super villainess in the Marvel Universe
* Ape-X, a super-intelligent ape in the Squadron Supreme universe
*Apex, ...
, sometimes obscurely so. The stipules are in the
axil
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
s of the leaves, sometimes enclosing an axillary
bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be spec ...
.
The
inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
is a cluster of axillary
raceme
A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...
s or
spike
Spike, spikes, or spiking may refer to:
Arts, entertainment, and media
Books
* ''The Spike'' (novel), a novel by Arnaud de Borchgrave
* ''The Spike'' (book), a nonfiction book by Damien Broderick
* ''The Spike'', a starship in Peter F. Hamilto ...
s, the clusters often being reduced to a pair of racemes or to a single raceme. The
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s are bisexual and
actinomorphic
Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts.
Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...
. The
sepal
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...
s are 4 to 7 in number, and
free, that is, separate from each other. ''Medusandra'' and ''Soyauxia'' have five
petal
Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...
s. ''Peridiscus'' and ''Whittonia'' have none.
''Medusandra'' lacks a
nectar
Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...
y disk and has five
stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
s, inserted opposite the petals, and alternating with five long, hairy
staminode
In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen.Jackson, Benjamin, Daydon; ''A Glossary of Botanic Terms with their Derivation and Accent''; Published by Gerald Duckworth & Co. ...
s. In the others, the stamens are
numerous and arranged in a ring around the nectary disk. The
anther
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filam ...
s are tetra
theca
In biology, a theca (plural thecae) is a sheath or a covering.
Botany
In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a commo ...
l in ''Medusandra'' and ''Soyauxia''; bithecal in ''Peridiscus'' and ''Whittonia''.
The
perianth
The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepals when ...
parts are attached below the
ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
. The ovary is therefore
superior, but appears half-inferior in ''Peridiscus'' because the ovary is embedded in the large, fleshy disk. The
gynoecium
Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...
consists of three or four
carpel
Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...
s, united to form a
unilocular
A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus).
In angiosperms (flowering plants), the term ''locule'' usu ...
ovary. The
placentation
Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove ...
is apical, with two
ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...
s at the apex of each carpel. The ovary has a central column in ''Medusandra'' and ''Soyauxia''. Each carpel bears a
stylulus and these are well separated at the apex of the ovary.
The
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
is one-
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
ed; a
capsule in ''Medusandra'' and ''Soyauxia''; a
drupe
In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...
in ''Peridiscus'' and ''Whittonia''.
History
George Bentham
George Bentham (22 September 1800 – 10 September 1884) was an English botanist, described by the weed botanist Duane Isely as "the premier systematic botanist of the nineteenth century". Born into a distinguished family, he initially studi ...
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
The Flacourtiaceae is a defunct family of flowering plants whose former members have been scattered to various families, mostly to the Achariaceae and Salicaceae. It was so vaguely defined that hardly anything seemed out of place there and it beca ...
.
[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).] Bentham wrote no
etymology
Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...
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.
[Umberto Quattrocchi. 2000. ''CRC World Dictionary of Plant Names''. volume III, page 2010. CRC Press: Baton Rouge, New York, London, Washington DC. . (see ''External links'' below)]
Daniel Oliver established the genus ''Soyauxia'' in 1880 for ''
Soyauxia gabonensis'', placing it in the family
Passifloraceae
The Passifloraceae are a family of flowering plants, containing about 750 species classified in around 27 genera.
They include trees, shrubs, lianas, and climbing plants, and are mostly found in tropical regions. The family takes its name from t ...
.
[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).] He named it for the
German
German(s) may refer to:
* Germany (of or related to)
** Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
botanist and plant collector
Hermann Soyaux,
[Umberto Quattrocchi. 2000. ''CRC World Dictionary of Plant Names''. volume IV, page 2521. CRC Press: Baton Rouge, New York, London, Washington DC. .] 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".
The family Flacourtiaceae was, as
Hermann Sleumer
Hermann Otto Sleumer (February 21, 1906 in Saarbrücken – October 1, 1993 in Oegstgeest) was a Dutch botanist of German birth. The plant genera ''Sleumerodendron'' Virot (Proteaceae
The Proteaceae form a family of flowering plants predomina ...
said, a fiction,
[Regis B. Miller (1975). "Systematic anatomy of the xylem and comments on the relationships of Flacourtiaceae". ''Journal of the Arnold Arboretum'' 56(1):79.][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.] and ''Peridiscus'' was, from the outset, one of its most doubtful members.
Recognizing its distinctiveness,
João Kuhlmann segregated it into its own family in 1947.
[João G. Kuhlmann. 1947. "Peridiscaceae (Kuhlmann)". ''Arquivos do Serviço Florestal'' 3(1):3-7.]
In 1952,
John Brenan named and described ''Medusandra'', erecting a new family,
Medusandraceae to accommodate it.
[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.] In 1953, Brenan transferred ''Soyauxia'' from Passifloraceae to Medusandraceae,
[John P.M. Brenan. 1953. "''Soyauxia'', a second genus of Medusandraceae". ''Kew Bulletin'' 8:507-511.] but few others agreed with his classification. In 1954,
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.
In 1962, Noel Y. Sandwith named and described ''Whittonia''.
[Noel Y. Sandwith. 1962. "Contributions to the flora of tropical America: LXIX. A new genus of Peridiscaceae". ''Kew Bulletin'' 15:467-471.] 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
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...
for the
''rbcL'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
of ''Whittonia'' was produced and used in a
molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
study of the
eudicots
The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons.
Traditionally they were called tricolpates or non-magnoliid dico ...
.
[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
Pamela Soltis (born November 13, 1957) is an American botanist. She is a distinguished professor at the University of Florida, curator at the Florida Museum of Natural History, principal investigator of the Laboratory of Molecular Systematics an ...
, Peter Weston, W. Mark Whitten, Kenneth J. Wurdack and Mark W. Chase
Mark Wayne Chase (born 1951) is a US-born British botanist. He is noted for work in plant classification and evolution, and one of the instigators of the Angiosperm Phylogeny Group-classification for flowering plants which is partly based on DNA ...
. 2000. "Phylogeny of the eudicots: a nearly complete familial analysis based on ''rbcL'' gene sequences". ''Kew Bulletin'' 55(2):257-309. This study placed Peridiscaceae in a
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
with
Elatinaceae
Elatinaceae is a family of flowering plants with ca 35 (to perhaps 50) species in two genera: ''Elatine'' and ''Bergia''. The ''Elatine'' are mostly aquatic herbs, and the ''Bergia'' are subshrubs to shrubs. ''Elatine'' species are widely distri ...
and
Malpighiaceae
Malpighiaceae is a family of flowering plants in the order Malpighiales. It comprises about 73 genera and 1315 species, all of which are native to the tropics and subtropics. About 80% of the genera and 90% of the species occur in the New World ( ...
, a very surprising and unexpected result. On the basis of this
phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
, the
Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disco ...
placed Peridiscaceae in
Malpighiales
The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinsett ...
when they published the
APG II system
The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Gro ...
of
plant classification in 2003.
[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.] It was soon found that the ''rbcL'' sequence for ''Whittonia'' was a
chimera
Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to:
* Chimera (mythology), a fire-breathing monster of Ancient Lycia said to combine parts from multiple animals
* Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...
, formed by
DNA from unidentified plants that had contaminated the
sample
Sample or samples may refer to:
Base meaning
* Sample (statistics), a subset of a population – complete data set
* Sample (signal), a digital discrete sample of a continuous analog signal
* Sample (material), a specimen or small quantity of s ...
.
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
sister
A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...
families and that Peridiscaceae belong to Saxifragales.
''Medusandra'' and ''Soyauxia'', meanwhile, were listed in APG II in an appendix entitled "TAXA OF UNCERTAIN POSITION".
DNA from ''Soyauxia'' was eventually obtained, and in 2007, it was shown that ''Soyauxia'' is most closely related to ''Peridiscus'' and, presumably, ''Whittonia''. Since this result has a good
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.
In 2008, in a study employing a large amount of
chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
DNA data, as well as some
mitochondrial
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...
and
nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
*Nuclear space
*Nuclear ...
DNA, it was shown that Peridiscaceae is sister to the rest of Saxifragales.
[Shuguang Jian, ]Pamela S. Soltis
Pamela Soltis (born November 13, 1957) is an American botanist. She is a distinguished professor at the University of Florida, curator at the Florida Museum of Natural History, principal investigator of the Laboratory of Molecular Systematics an ...
, 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.
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, finding strong support for a clade of
'Medusandra'' + (''Soyauxia'' + ''Peridiscus'') When the
APG III system
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a fur ...
was published in October 2009, Peridiscaceae was
expanded to include ''Medusandra'' and ''Soyauxia''.
[ John Brenan, 57 years before, had been prescient in his perception of a relationship between ''Medusandra'' and ''Soyauxia''.
]
Phylogeny
The phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
is diagrammed as a phylogenetic tree
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
below. The relationships shown are from Wurdack and Davis (2009) except for the position of ''Whittonia'', for which no DNA sequences are known. ''Peridiscus'' and ''Whittonia'' are undoubtedly sister
A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
due to their many shared morphological characters.
References
Bibliography
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;Websites
Peridiscaceae
At
At
Missoure Botanical Garden Website
CRC World Dictionary of Plant Names: M-Q
At
Hooker's Icones Plantarum
in L. Watson and M.J. Dallwitz (1992 onwards)
The families of flowering plants
descriptions, illustrations, identification, information retrieval.
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{{Taxonbar, from=Q132930
Saxifragales families