Parnassiaceae

Gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...

were 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 ...

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

eudicot 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 dicot ...

order

Celastrales The Celastrales are an order of flowering plants found throughout the tropics and subtropics, with only a few species extending far into the temperate regions. The 1200"Lepidobotryaceae", "Parnassiaceae", and "Celastraceae" In: Klaus Kubitzki (ed ...

.Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. (2007). The family is not recognized in 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 Published in 2009, it was superseded in 2016 by a fur ...

of plant classification.Angiosperm Phylogeny Group. 2009. "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". ''Botanical Journal of the Linnean Society'' 161(2):105-121. (see ''External links'' below). When that

system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, ...

was published in 2009, Parnassiaceae were treated as subfamily Parnassioideae of an expanded family

Celastraceae The Celastraceae (staff-vine or bittersweet) are a family of 97 genera and 1,350 species of herbs, vines, shrubs and small trees, belonging to the order Celastrales. The great majority of the genera are tropical, with only ''Celastrus'' (the staf ...

.Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see external links below) Parnassiaceae have only two

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 ...

, ''

Lepuropetalon ''Lepuropetalon'' is a genus of flowering plants in the family Celastraceae. Before it was placed in the family when it was defined by the Angiosperm Phylogeny Group's APG III system in 2009, it had been placed with ''Parnassia'' in the family ...

'' and ''

Parnassia The genus ''Parnassia'', also known as grass of Parnassus or bog-stars, are plants now placed in the family Celastraceae, formerly classified in Parnassiaceae or Saxifragaceae. The plants occur in arctic and alpine habitats, as well as in dune ...

''.Mark P. Simmons "Parnassiaceae" In: Klaus Kubitzki (ed.). ''The Families and Genera of Vascular Plants'' vol. VI. Springer-Verlag: Berlin,Heidelberg (2004). ''Lepuropetalon'' has only one

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''

Lepuropetalon spathulatum ''Lepuropetalon'' is a genus of flowering plants in the family Celastraceae. Before it was placed in the family when it was defined by the Angiosperm Phylogeny Group's APG III system in 2009, it had been placed with ''Parnassia'' in the family P ...

'', a

winter annual An annual plant is a plant that completes its biological life cycle, life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary accor ...

that usually prefers

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

. It is one of the smallest of flowering plants, up to 2 cm tall.Stephen A. Spongberg (1972). "Parnassioideae" pages 458-466 In: "The genera of Saxifragaceae in the southeastern United States" ''Journal of the Arnold Arboretum'' 53(4):409-498. ''Lepuropetalon'' 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 ...

, being known from the southeastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and central

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

,Adolf Engler (1930). "Saxifragaceae" In: Adolf Engler and Karl Prantl (eds.). ''Die Naturlichen Pflanzenfamilien, edition 2'' vol.18a:178-182. but is probably far more common than has been reported.Daniel B. Ward and Angus K. Gholson (1987). "The hidden abundance of ''Lepuropetalon spathulatum''(Saxifragaceae) and its first recorded occurrence in Florida". ''Castanea'' 52(1):59-67. ''Parnassia'' is a genus of

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

herbs In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

, up to 60 cm tall, that grow in bogs,

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

es, and other wet areas, mostly in cool to cold

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

s of the north

temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

. There are at least 70 species.Ding Wu, Hong Wang, De-Zhu Li, and Steven Blackmore (2005). "Pollen Morphology of Parnassia L. (Parnassiaceae) and Its Systematic Implications". ''Journal of Integrative Plant Biology'' 47(1):2-12. (see external links below). Sixty-three species occur in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and 49 of these occur nowhere else.Gu Cuizhi and Ulla-Maj Hultgård (2001). "Parnassia" In: Wu Zheng-yi and Peter H. Raven. ''Flora of China'' vol.8:358-379. Science Press: Beijing. Missouri Botanical Garden Press: St. Louis, MO, USA. A second area of

diversity Diversity, diversify, or diverse may refer to: Business *Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce *Diversity marketing, marketing communication targeting diverse customers * ...

for ''Parnassia'' is

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and about 9 species occur there.USDA Plants Database (see external links below) ''

Parnassia palustris ''Parnassia palustris'', the marsh grass of Parnassus, northern grass-of-Parnassus, or just grass-of-Parnassus, and bog star, is a flowering plant in the staff-vine family Celastraceae. It is the county flower of Cumberland in England, and appea ...

'' is the most well known and widely distributed species. It ranges through most of northern

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, and the western

.Raymond B. Phillips (1982). "Systematics of Parnassia (Parnassiaceae): Generic overview and revision of North American taxa". Ph.D thesis. University of California at Berkeley. ''Parnassia palustris'' is widely cultivated. About 10 species are known in cultivation, all as

ornamentals Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...

Anthony Huxley Anthony Julian Huxley (2 December 1920 – 26 December 1992) was a British botanist. He edited '' Amateur Gardening'' from 1967 to 1971, and was vice-president of the Royal Horticultural Society in 1991. He was the son of Julian Huxley. He was ...

, Mark Griffiths, and Margot Levy (1992). ''The New Royal Horticultural Society Dictionary of Gardening''. The Macmillan Press,Limited: London. The Stockton Press: New York.

Description

Parnassiaceae are

rhizomatous In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

(''Parnassia'') or winter annuals without a rhizome (''Lepuropetalon''). The youngest part of the stem has three collateral

vascular bundle A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will inclu ...

s. On the stems, leaves, and flowers, the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...

has sacs filled with

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...

. The leaves are

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 ...

or subopposite, without

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

s, and the margins 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 ...

. The leaf

blade A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historic ...

is wide compared to its length and the secondary venation is subpalmate. In ''Parnassia'', the leaves are crowded into a basal rosette with a few

cauline 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 ...

leaves above. The leaves are all cauline in ''Lepuropetalon''. In both genera, the lower cauline leaves are pseudosessile, which means that the petioles are

adnate Adnate may refer to: * Adnation, in botany, the fusion of two or more whorls of a flower * Adnate, in mycology, a classification of lamellae (gills) * Conjoined twins Conjoined twins – sometimes popularly referred to as Siamese twins – are ...

to the stems. The upper cauline leaves, if present, are truly

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

. 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 ...

consists of one, or rarely two, flowers that face upward and are at the end of a peduncle that has few or no leaves. 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 perfect and slightly

zygomorphic 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 five

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 shortly connate at their bases, and

persistent Persistent may refer to: * Persistent data * Persistent data structure * Persistent identifier * Persistent memory * Persistent organic pollutant * Persistent Systems, a technology company * USS ''Persistent'', three United States Navy ships See ...

through maturity of the fruit. The

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 are either absent, or five and

free Free may refer to: Concept * Freedom, having the ability to do something, without having to obey anyone/anything * Freethought, a position that beliefs should be formed only on the basis of logic, reason, and empiricism * Emancipate, to procur ...

from each other. In ''Parnassia'', the petals are showy and white or cream, with conspicuous veins that are usually green or gray. The margins are

, toothed, or fimbriate. In ''Lepuropetalon'', the petals are rudimentary or absent. In both genera, the 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 are free from each other. They are placed opposite the sepals and therefore alternate with the petals. 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 open in sequence above 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'' ...

(see next section). The five

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 are free and placed opposite the petals. They mature after the stamens. Each consists of 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 ...

iferous pad with filamentous rays arising from its edge. Each ray is terminated by a large globular gland. 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. ...

is superior or half inferior and consists of 3 or 4, rarely 5, fused

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. The walls of the carpels are incomplete so that the ovary is

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 ...

in its upper part. 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 parietal. The

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 are attached to T-shaped placentas in ''Parnassia'', and directly to the ovary wall in ''Lepuropetalon''. The

style Style is a manner of doing or presenting things and may refer to: * Architectural style, the features that make a building or structure historically identifiable * Design, the process of creating something * Fashion, a prevailing mode of clothing ...

is absent or very short. The stigmas are

decurrent ''Decurrent'' (sometimes decurring) is a term used in botany and mycology to describe plant or fungal parts that extend downward. In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petio ...

along the

commissure A commissure () is the location at which two objects abut or are joined. The term is used especially in the fields of anatomy and biology. * The most common usage of the term refers to the brain's commissures, of which there are five. Such a commi ...

s of the ovary and sometimes extended above, to form false styles called

stylodia The stigma () is the receptive tip of a Gynoecium#Carpels, carpel, or of several fused carpels, in the gynoecium of a flower. Description The stigma, together with the style and ovary (botany), ovary (typically called the stigma-style-ovary ...

. The stigmatic areas are dry. The

megagametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...

is of the ''Polygonum'' type. 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 an erect, membranous capsule, which opens at the

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 ...

only. The

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 ...

s are small, light, and numerous.

Oddities

Parnassias are often grown as curiosities for their unique and prominent

s. Further examination reveals additional oddities. The lowest leaves on the stem appear to be

, but in fact the petiole is

to the stem and embedded in it. The conductive vessels that enervate the leaf depart from those of the stem far below where the leaf is attached. As soon as the flower opens, the stamens begin to elongate. One of them bends inward, opens the

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 ...

e of its

, and dumps its

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

on the

. It then bends away from the ovary to the outside of the flower. Another stamen then repeats this process. It takes about one day for a stamen to complete its motions, and the order in which they do so varies from one flower to another. The area that is receptive to pollen, the stigmatic area, is not confined to the apex of the ovary or mounted on a

as in most flowers, but extends in bands down the sides of the ovary along the

s, the seams where the

s that compose the ovary are joined together. Such commissural stigmas have been discovered in

,Merran L. Matthews and Peter K. Endress (2005). "Comparative floral structure and systematics in Celastrales". ''Botanical Journal of the Linnean Society'' 149 (2):129-194 but as late as 1972, they were known only from Parnassiaceae and from the basal eudicot family

Papaveraceae The Papaveraceae are an economically important family of about 42 genera and approximately 775 known species of flowering plants in the order Ranunculales, informally known as the poppy family. The family is cosmopolitan, occurring in temperat ...

. ''Lepuropetalon'' shares with ''Parnassia'' the pseudosessile leaves and the commissural stigmas. It also dumps its pollen on the ovary, but without the elaborate dance of the stamens. Unlike ''Parnassia'', however, its staminodes are small and lack glands.

Relationships

The genus ''Parnassia'' was named by

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

in 1753 for

Mount Parnassus Mount Parnassus (; el, Παρνασσός, ''Parnassós'') is a mountain range of central Greece that is and historically has been especially valuable to the Greek nation and the earlier Greek city-states for many reasons. In peace, it offers ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...

.Linnaeus (1753). ''Species Plantarum'' vol.1, page 273. (see external links below). In 1821,

Samuel Frederick Gray Samuel Frederick Gray (10 December 1766 – 12 April 1828) was a British botanist, mycologist, and pharmacologist. He was the father of the zoologists John Edward Gray and George Robert Gray. Background He was the son of Samuel Gray, a London s ...

put ''Parnassia'' in its own family, Parnassiaceae.Samuel Frederick Gray (1821). ''A Natural Arrangement of British Plants According to Their Relations to Each Other...'' vol.II pages 623 and 670. Baldwin, Craddock, and Joy: London. (see external links below). In that same year,

Stephen Elliott Stephen Elliott may refer to: Entertainment *Stephen Elliott (actor), (1918–2005), American actor * Stephen Elliott (author) (born 1971), American author and activist Sport *Steve Elliott (footballer, born 1958), English footballer *Steve Ellio ...

gave ''Lepuropetalon'' its name and published a description of it.Stephen Elliott (1821). ''A Sketch of the Botany of South-Carolina and Georgia'' vol.I page 370. J.R. Schenck: Charleston, SC, USA. (see external links below). The name is from two

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words, ''lepyron'', "husk, rind, or shell", and ''petalon'', "leaf or petal".Umberto Quattrocchi (2000). ''CRC World Dictionary of Plant Names'' vol.II, page 1474. CRC Press. In 1930, botanist

Adolf Engler Heinrich Gustav Adolf Engler (25 March 1844 – 10 October 1930) was a German botanist. He is notable for his work on plant taxonomy and phytogeography, such as ''Die natürlichen Pflanzenfamilien'' (''The Natural Plant Families''), edited with ...

published descriptions of ''Lepuropetalon'' and ''Parnassia'' with detailed illustrations. He did not consider them to be closely related and placed each in its own subfamily among the 15 subfamilies that he recognized in

Saxifragaceae Saxifragaceae is a family of herbaceous perennial flowering plants, within the core eudicot order Saxifragales. The taxonomy of the family has been greatly revised and the scope much reduced in the era of molecular phylogenetic analysis. The f ...

. Others thought that they were closely related. One of these was Steven Spongberg, who did a detailed study of ''Lepuropetalon'' and placed it in Saxifragaceae in the same subfamily with ''Parnassia''. Most authors have followed Engler or Spongberg in their treatment of these two genera, but often with considerable doubt. Several other possible relationships have been proposed. In 2001, a DNA study showed that ''Lepuropetalon'' and ''Parnassia'' were much closer to each other than to any others.Mark P. Simmons,

Vincent Savolainen Vincent Savolainen is a biologist. Savolainen was born on 27 September 1966. He is of Finnish origin and holds Swiss, British, and French citizenship. Savolainen earned his undergraduate degree from the University of Geneva and obtained his doctor ...

, Curtis C. Clevinger, Robert H. Archer, and Jerrold I. Davis (2001). "Phylogeny of Celastraceae Inferred from 26S Nuclear Ribosomal DNA, Phytochrome B, rbcL, atpB, and Morphology". ''Molecular Phylogenetics and Evolution'' 19(3):353-366. This was the first DNA study to give strong statistical support (98% bootstrap support) for this relationship. In 2005, a study of flower structure concluded that the family Parnassiaceae belonged in the order

with

Lepidobotryaceae Lepidobotryaceae is a family of plants in the order Celastrales."Lepidobotryaceae" In: Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see External links below). It contains only two species: ...

, and a broadly defined

, including '' Mortonia'' and ''

Pottingeria ''Pottingeria'' is a genus consisting of a single species, ''Pottingeria acuminata'', a small tree or large shrub native to mountainous areas of southeast Asia (Assam, Myanmar, and Thailand). It had long been thought, at least by some, to belong ...

''. In 2006, a study of

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 ...

s confirmed that ''Lepuropetalon'' and ''Parnassia'' form a strongly supported

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, ...

.Li-Bing Zhang and Mark P. Simmons (2006). "Phylogeny and Delimitation of the Celastrales Inferred from Nuclear and Plastid Genes". ''Systematic Botany'' 31(1):122-137. This study also showed strong

support Support may refer to: Arts, entertainment, and media * Supporting character Business and finance * Support (technical analysis) * Child support * Customer support * Income Support Construction * Support (structure), or lateral support, a ...

for a pentatomy consisting of ''

'', '' Mortonia'', Parnassiaceae, and two clades of

from

as that family had been

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

APG II 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 Gr ...

. The relationships between these five clades remain unresolved. In 2009, 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 ...

expanded the family Celastraceae to consist of the five clades of the pentatomy mentioned above. A

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

infrafamilial

classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

of Celastraceae

sensu ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

APG III has not yet been published.

References

External links

* APG III
Parnassia pollen
Ding Wu et alii (2005) In
Journal of Integrative Plant Biology
*
Species Plantarum

''A Natural Arrangement of British Plants...''

A Sketch of the Botany of South Carolina and Georgia
{{Taxonbar, from=Q162149 Celastrales Historically recognized angiosperm families