Lepuropetalon
Encyclopedia
Lepuropetalon is a genus
of flowering plant
s in the family
Celastraceae
as that family was defined
by the Angiosperm Phylogeny Group
in 2009. Before the publication of the APG III system
in 2009, Lepuropetalon had been placed with Parnassia in the family Parnassiaceae
, now usually treated as a segregate
of Celastraceae. Lepuropetalon has only one species
, Lepuropetalon spathulatum. It is a winter annual that is most abundant in eastern Texas
and western Louisiana
. From there, it occurs sporadically southward into Mexico
, and eastward thru the Atlantic and Gulf coastal plain, and rarely in the Piedmont Plateau
, to North Carolina
. It has a disjunct distribution
. In addition to the area mentioned above, it is also found in Uruguay
and central Chile
.
It is one of the smallest of terrestrial
flowering plants and some consider it to be the smallest. Because it is so easily overlooked, it is probably much more abundant than records indicate. It is found in moist areas, usually in soils that are sand
y or derived from granite
. It is common along the edges of soil-filled depressions on top of rocks. It is often seen in cemeteries and clearings for power lines. Because it is common in habitat
s that are maintained by humans, but not intensively cultivated, it is probably more abundant now than it was naturally.
In the United States
and Mexico
, the seeds germinate
in January. It has been suggested that this is a response to increasing day length, but no experiments have confirmed it. Flowering
is in March and early April. Seed maturity follows quickly. Few plants survive beyond the end of April.
sacs of tannin
that tend to be arranged in lines. These are golden-brown or slightly reddish in color. The stems are rather thick and slightly angled. The leaves are alternate or subopposite
in arrangement, sessile
, long, and wide at the end like a spoon or spatula.
The flowers are solitary on the ends of stems, immediately above the leaves, and usually face upward. They are large compared to the rest of the plant, 2 to 3mm in diameter with male and female parts both present and functional. The calyx consists of five broad, often unequal sepal
s that are joined in the lower part to form a floral cup
that encloses the lower half of the ovary
and is thickened along its fissures to form five ribs. The sepals persist beyond the maturity of the fruit
.
The petal
s are scale-like, white and barely visible, on the rim of the floral cup between the sepals, or sometimes absent. They die but remain, along with the sepals.
The five stamen
s are short and opposite the sepals. Initially, they are turned inward and dump their pollen
on the ovary. Eventually, they are bent outward by the expansion of the ovary. The anthers are yellow, erect, and subglobular. The five staminode
s are opposite the petals and dilated at the ends.
The gynoecium
is unilocular
and composed of three fused carpels. The ovule
s are numerous and attached near the margins of the carpels. The three stigma
s are separate or initially joined at the base, but soon separating with growth of the ovary. The stigmas are commissural
, meaning that the area that is receptive to pollen extends downward along the fissures where the carpels are joined.
The fruit
is a capsule
. The seed
s are numerous and cylindrical, .15 to .2mm long, reddish when immature, and nearly black when ripe.
of Catalogus Plantarum Americae Septentrionalis (Catalog of the Plants of North America). Muhlenberg named the plant Pyxidanthera spatulata, but it is now known that Lepuropetalon is not related to Pyxidanthera, the latter being a member of the family Diapensiaceae
in the order Ericales
. Muhlenberg's name is, in any case, considered a nomen nudum
because his description can not be used to identify the plant. Muhlenberg's information on this plant, and probably some specimen
s as well, almost certainly came from his friend and correspondent, Stephen Elliott
of South Carolina
. Parts of the herbaria
created by Elliott and Muhlenberg are still preserved, but the specimens of Lepuropetalon are lost from both of them.
In 1817, Stephen Elliott published one of the booklets that would be combined in 1821 to become volume I of the work for which he is still remembered, A Sketch of the Botany of South Carolina and Georgia. In this book, he mentions Pyxidanthera spatulata, but gives the specific epithet the more conventional Latin spelling of "spathulatum". He departed from Muhlenberg's classification, however, by placing the plant in its own genus, which he named Lepuropetalon.
Elliott gave a very brief Latin description which he translated as
He then gave a detailed description of the plant and mentions that it had also been collected by William Baldwin
.
Elliott wrote no etymology
for the name, and subsequent authors have differed on its interpretation. All agree that the name is of Greek
derivation and that "petalon" is the Greek term for "petal or leaf". However, some say that the first part is derived from lepyron, "a husk or shell", referring to the inclusion of the petals within the calyx, while others say that it is from lepro, meaning "scaly", and referring to the scale-like petals.
In 1833, William Jackson Hooker
in England
described Lepuropetalon from material that a collector had sent from Chile
. At about the same time, John Torrey in New York
received some material from Louisiana
. John Torrey and Asa Gray
wrote about Lepuropetalon in 1840. Alvan Wentworth Chapman
wrote of it in 1860, 1884, and 1897, in the three editions of Flora of the Southern United States.
Lepuropetalon was mentioned in several other publications in the nineteenth and twentieth centuries, but it remained little known and it was seldom collected for herbaria. There are about 90 known collections of it before 1970. In the 1970s, interest in Lepuropetalon increased and by 1987, when Ward and Gholson wrote of it, there had been 263 collections. Collectors at that time observed that once one learned what sort of areas to look in, Lepuropetalon was easily found. Ward and Gholson provide a detailed map of its distribution in the United States.
or segregated with Parnassia to form the family Parnassiaceae
. In 1993, a phylogeny of Saxifragaceae was published, based on DNA sequence
s of the chloroplast
gene
rbcL, which codes
for the large subunit
of the carbon dioxide fixing
enzyme
RuBisCO
. This study found Saxifragaceae sensu lato to be polyphyletic
with Lepuropetalon, Parnassia, and several others unrelated to the core of the family. Saxifragaceae is now defined much more narrowly than it was in 1993, and now comprises about 30 genera.
As Lepuropetalon and its sister Parnassia were being tossed out of Saxifragales
, they were landing in Celastrales
. The first very large DNA sequence comparison for flowering plants included both of them and was based on rbcL. The phylogeny produced by this study placed Lepuropetalon and Parnassia together, but only four members of Celastrales were sampled and the authors could not calculate statistical support for their clade
s.
In 2000, an rbcL phylogeny of eudicots
again put Lepuropetalon and Parnassia together, but with only weak statistical support.
In 2001, in a study that used much more DNA, Lepuropetalon again grouped with Parnassia, but with strong statistical support (98% bootstrap
percentage). This was confirmed in 2006 in the first study to sample all of the major clades in Celastrales.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Celastraceae
Celastraceae
The Celastraceae , is a family of about 90-100 genera and 1,300 species of vines, shrubs and small trees, belonging to the order Celastrales...
as that family was defined
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
by the Angiosperm Phylogeny Group
Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants that would reflect new knowledge about plant relationships discovered through phylogenetic studies., three...
in 2009. Before the publication of the APG III system
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...
in 2009, Lepuropetalon had been placed with Parnassia in the family Parnassiaceae
Parnassiaceae
Parnassiaceae Gray is a family of Flowering plants in the eudicot order Celastrales. It is not recognized in the APG III system of plant classification. When that system was published in 2009, Parnassiaceae was treated as a segregate of an expanded Celastraceae. Parnassiaceae has only two...
, now usually treated as a segregate
Segregate (taxonomy)
In taxonomy, a segregate, or a segregate taxon is created when a taxon is split off, from another taxon. This other taxon will be better known, usually bigger, and will continue to exist, even after the segregate taxon has been split off...
of Celastraceae. Lepuropetalon has only one species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Lepuropetalon spathulatum. It is a winter annual that is most abundant in eastern Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and western Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
. From there, it occurs sporadically southward into Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, and eastward thru the Atlantic and Gulf coastal plain, and rarely in the Piedmont Plateau
Piedmont (United States)
The Piedmont is a plateau region located in the eastern United States between the Atlantic Coastal Plain and the main Appalachian Mountains, stretching from New Jersey in the north to central Alabama in the south. The Piedmont province is a physiographic province of the larger Appalachian division...
, to North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. It has a disjunct distribution
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...
. In addition to the area mentioned above, it is also found in Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
and central Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
.
It is one of the smallest of terrestrial
Terrestrial plant
A terrestrial plant is one that grows on land. Other types of plants are aquatic , epiphytic , lithophytes and aerial ....
flowering plants and some consider it to be the smallest. Because it is so easily overlooked, it is probably much more abundant than records indicate. It is found in moist areas, usually in soils that are sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y or derived from granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
. It is common along the edges of soil-filled depressions on top of rocks. It is often seen in cemeteries and clearings for power lines. Because it is common in habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s that are maintained by humans, but not intensively cultivated, it is probably more abundant now than it was naturally.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, the seeds germinate
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
in January. It has been suggested that this is a response to increasing day length, but no experiments have confirmed it. Flowering
Anthesis
Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period.The onset of anthesis is spectacular in some species. In Banksia species, for example, anthesis involves the extension of the style far beyond the upper perianth parts...
is in March and early April. Seed maturity follows quickly. Few plants survive beyond the end of April.
Description
Lepuropetalon spathulatum is a diminutive winter annual. In favorable conditions, it forms a hemispherical tuft, up to 2 cm tall and wide, rarely larger. It often consists of no more than a single flower above a few tiny leaves, the whole plant being less than 5 mm high and 5mm across. The stems, leaves, and flowers are conspicuously dotted with epidermalEpidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...
sacs of tannin
Tannin
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...
that tend to be arranged in lines. These are golden-brown or slightly reddish in color. The stems are rather thick and slightly angled. The leaves are alternate or subopposite
Phyllotaxis
In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem .- Pattern structure :...
in arrangement, sessile
Sessility (botany)
In botany, sessility is a characteristic of plants whose flowers or leaves are borne directly from the stem or peduncle, and thus lack a petiole or pedicel...
, long, and wide at the end like a spoon or spatula.
The flowers are solitary on the ends of stems, immediately above the leaves, and usually face upward. They are large compared to the rest of the plant, 2 to 3mm in diameter with male and female parts both present and functional. The calyx consists of five broad, often unequal sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s that are joined in the lower part to form a floral cup
Hypanthium
A hypanthium is a floral structure consisting of the bases of the sepals, petals, and stamens fused together. Its presence is diagnostic of many families, including the Rosaceae, Grossulariaceae, and Fabaceae...
that encloses the lower half of the ovary
Ovary (plants)
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
and is thickened along its fissures to form five ribs. The sepals persist beyond the maturity of the fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
.
The petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are scale-like, white and barely visible, on the rim of the floral cup between the sepals, or sometimes absent. They die but remain, along with the sepals.
The five stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s are short and opposite the sepals. Initially, they are turned inward and dump their pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
on the ovary. Eventually, they are bent outward by the expansion of the ovary. The anthers are yellow, erect, and subglobular. The five staminode
Staminode
In botany, a staminode is an often rudimentary, sterile or abortive stamen. This means that it does not produce pollen. Staminodes are frequently inconspicuous and stamen-like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the...
s are opposite the petals and dilated at the ends.
The gynoecium
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
is unilocular
Locule
A locule is a small cavity or compartment within an organ or part of an organism ....
and composed of three fused carpels. The ovule
Ovule
Ovule means "small egg". 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 , and the megaspore-derived female gametophyte in its center...
s are numerous and attached near the margins of the carpels. The three stigma
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
s are separate or initially joined at the base, but soon separating with growth of the ovary. The stigmas are commissural
Commissure
A commissure is the place where two things are joined. The term is used especially in the fields of anatomy and biology.In anatomy, commissure refers to a bundle of nerve fibers that cross the midline at their level of origin or entry .* The most common usage of the term refers to the brain's...
, meaning that the area that is receptive to pollen extends downward along the fissures where the carpels are joined.
The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a capsule
Capsule (fruit)
In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels that in most cases is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example...
. The seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s are numerous and cylindrical, .15 to .2mm long, reddish when immature, and nearly black when ripe.
History
Lepuropetalon spathulatum entered the botanical literature in 1813 with the publication by Henry MuhlenbergGotthilf Heinrich Ernst Muhlenberg
Gotthilf Heinrich Ernst Muhlenberg was an American clergyman and botanist.-Biography:The son of Heinrich Melchior Muhlenberg, he was born in Trappe, Pennsylvania. He was educated at in Halle starting in 1763 and in 1769 at the University of Halle. He returned to Pennsylvania in September 1770...
of Catalogus Plantarum Americae Septentrionalis (Catalog of the Plants of North America). Muhlenberg named the plant Pyxidanthera spatulata, but it is now known that Lepuropetalon is not related to Pyxidanthera, the latter being a member of the family Diapensiaceae
Diapensiaceae
Diapensiaceae is a small family of flowering plants, comprising 12 species in five genera. Three of the genera, Berneuxia, Galax, and Pyxidanthera, contain only a single species. The Asian species of Shortia were formerly separated as the genus Schizocodon, and some authors still recognize S....
in the order Ericales
Ericales
The Ericales are a large and diverse order of dicotyledons, including for example tea, persimmon, blueberry, Brazil nut, and azalea. The order includes trees and bushes, lianas and herbaceous plants. Together with ordinary autophytic plants, the Ericales include chlorophyll-deficient...
. Muhlenberg's name is, in any case, considered a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
because his description can not be used to identify the plant. Muhlenberg's information on this plant, and probably some specimen
Specimen
A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...
s as well, almost certainly came from his friend and correspondent, Stephen Elliott
Stephen Elliott (botanist)
Stephen Elliott was an American legislator, banker, educator, and botanist who is today remembered for having written one of the most important works in American botany, A Sketch of the Botany of South-Carolina and Georgia.-Biography:Stephen Elliott was born in Beaufort, South Carolina on...
of South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
. Parts of the herbaria
Herbarium
In botany, a herbarium – sometimes known by the Anglicized term herbar – is a collection of preserved plant specimens. These specimens may be whole plants or plant parts: these will usually be in a dried form, mounted on a sheet, but depending upon the material may also be kept in...
created by Elliott and Muhlenberg are still preserved, but the specimens of Lepuropetalon are lost from both of them.
In 1817, Stephen Elliott published one of the booklets that would be combined in 1821 to become volume I of the work for which he is still remembered, A Sketch of the Botany of South Carolina and Georgia. In this book, he mentions Pyxidanthera spatulata, but gives the specific epithet the more conventional Latin spelling of "spathulatum". He departed from Muhlenberg's classification, however, by placing the plant in its own genus, which he named Lepuropetalon.
Elliott gave a very brief Latin description which he translated as
- "Calyx 5 parted. Petals 5, resembling scales, inserted into the calyx.
- Capsule free near the summit, 1 celled, 1 valved."
He then gave a detailed description of the plant and mentions that it had also been collected by William Baldwin
William Baldwin (botanist)
William Baldwin was an American physician and botanist who is today remembered for his significant contributions to botany. He lived in Pennsylvania, Delaware, and Georgia, and served as a ship's surgeon on two voyages overseas...
.
Elliott wrote no etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
for the name, and subsequent authors have differed on its interpretation. All agree that the name is of Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
derivation and that "petalon" is the Greek term for "petal or leaf". However, some say that the first part is derived from lepyron, "a husk or shell", referring to the inclusion of the petals within the calyx, while others say that it is from lepro, meaning "scaly", and referring to the scale-like petals.
In 1833, William Jackson Hooker
William Jackson Hooker
Sir William Jackson Hooker, FRS was an English systematic botanist and organiser. He held the post of Regius Professor of Botany at Glasgow University, and was the first Director of the Royal Botanic Gardens, Kew. He enjoyed the friendship and support of Sir Joseph Banks for his exploring,...
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
described Lepuropetalon from material that a collector had sent from Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. At about the same time, John Torrey in New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
received some material from Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
. John Torrey and Asa Gray
Asa Gray
-References:*Asa Gray. Dictionary of American Biography. American Council of Learned Societies, 1928–1936.*Asa Gray. Encyclopedia of World Biography, 2nd ed. 17 Vols. Gale Research, 1998.*Asa Gray. Plant Sciences. 4 vols. Macmillan Reference USA, 2001....
wrote about Lepuropetalon in 1840. Alvan Wentworth Chapman
Alvan Wentworth Chapman
Alvan Wentworth Chapman was an American physician and botanist who wrote Flora of the Southern United States, the first comprehensive description of US plants in any region beyond the northeastern states.-Education:...
wrote of it in 1860, 1884, and 1897, in the three editions of Flora of the Southern United States.
Lepuropetalon was mentioned in several other publications in the nineteenth and twentieth centuries, but it remained little known and it was seldom collected for herbaria. There are about 90 known collections of it before 1970. In the 1970s, interest in Lepuropetalon increased and by 1987, when Ward and Gholson wrote of it, there had been 263 collections. Collectors at that time observed that once one learned what sort of areas to look in, Lepuropetalon was easily found. Ward and Gholson provide a detailed map of its distribution in the United States.
Affinities
In the nineteenth and twentieth centuries, Lepuropetalon was placed in various families by different authors, but it was usually placed with Parnassia in SaxifragaceaeSaxifragaceae
Saxifragaceae is a plant family with about 460 known species in 36 genera. In Europe there are 12 genera.The flowers are hermaphroditic and actinomorphic...
or segregated with Parnassia to form the family Parnassiaceae
Parnassiaceae
Parnassiaceae Gray is a family of Flowering plants in the eudicot order Celastrales. It is not recognized in the APG III system of plant classification. When that system was published in 2009, Parnassiaceae was treated as a segregate of an expanded Celastraceae. Parnassiaceae has only two...
. In 1993, a phylogeny of Saxifragaceae was published, based on DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
rbcL, which codes
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
for the large subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
of the carbon dioxide fixing
Carbon fixation
In biology, carbon fixation is the reduction of carbon dioxide to organic compounds by living organisms. The obvious example is photosynthesis. Carbon fixation requires both a source of energy such as sunlight, and an electron donor such as water. All life depends on fixed carbon. Organisms that...
enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
RuBisCO
RuBisCO
Ribulose-1,5-bisphosphate carboxylase oxygenase, commonly known by the shorter name RuBisCO, is an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants to energy-rich molecules such as glucose. RuBisCo is an abbreviation...
. This study found Saxifragaceae sensu lato to be polyphyletic
Polyphyly
A polyphyletic group is one whose members' last common ancestor is not a member of the group.For example, the group consisting of warm-blooded animals is polyphyletic, because it contains both mammals and birds, but the most recent common ancestor of mammals and birds was cold-blooded...
with Lepuropetalon, Parnassia, and several others unrelated to the core of the family. Saxifragaceae is now defined much more narrowly than it was in 1993, and now comprises about 30 genera.
As Lepuropetalon and its sister Parnassia were being tossed out of Saxifragales
Saxifragales
Saxifragales is an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the rosids more widely, including Saxifragales as their most basal group. Saxifragales is...
, they were landing in Celastrales
Celastrales
Celastrales is an order of flowering plants. They are found throughout the tropics and subtropics, with only a few species extending far into the temperate regions. There are about 1200 to 1350 species in about 100 genera. All but 7 of these genera are in the large family Celastraceae...
. The first very large DNA sequence comparison for flowering plants included both of them and was based on rbcL. The phylogeny produced by this study placed Lepuropetalon and Parnassia together, but only four members of Celastrales were sampled and the authors could not calculate statistical support for their clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s.
In 2000, an rbcL phylogeny of eudicots
Eudicots
Eudicots and Eudicotyledons are botanical terms introduced by Doyle & Hotton to refer to a monophyletic group of flowering plants that had been called tricolpates or non-Magnoliid dicots by previous authors...
again put Lepuropetalon and Parnassia together, but with only weak statistical support.
In 2001, in a study that used much more DNA, Lepuropetalon again grouped with Parnassia, but with strong statistical support (98% bootstrap
Bootstrapping (statistics)
In statistics, bootstrapping is a computer-based method for assigning measures of accuracy to sample estimates . This technique allows estimation of the sample distribution of almost any statistic using only very simple methods...
percentage). This was confirmed in 2006 in the first study to sample all of the major clades in Celastrales.
External links
- CRC World Dictionary of Plant Names: D-L At: Botany & Plant Science At: Life Science At: CRC Press
- Flora of the Carolinas, Virginia and Georgia
- Catalogus Plantarum Americae Septentrionalis
- USDA Plants Database
- A Sketch of the Botany of South Carolina and Georgia
- Botanical Miscellany volume III
- A Flora of North America
- Flora of the Southern United States
