is a Japanese species of plants in the genus ''
Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), ma ...
'' in the family
Melanthiaceae
Melanthiaceae, also called the bunchflower family, is a family of flowering herbaceous perennial plants native to the Northern Hemisphere. Along with many other lilioid monocots, early authors considered members of this family to belong to t ...
.
[Ohwi, J. (1984). Flora of Japan (in English): 1-1067. Smithsonian Institution, Washington, D.C..]
It is native to
sub-alpine
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...
regions of
Japan. A slow growing perennial, it flowers in July. The rare, showy white star-like flower is borne above a single
whorl of about eight stem leaves. It prefers cool, humid, shady places.
Genetics
''Paris japonica'' has the largest
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
of any plant yet assayed, about 150 billion
base pairs long. An
octoploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...
and suspected
allopolyploid hybrid of four species, it has 40 chromosomes. With 150 billion base pairs of DNA per cell (50 times larger than that of a human haploid genome), ''Paris japonica'' may possess the largest known genome of any living organism; the DNA from a single cell stretched out end-to-end would be longer than .
[
The flower has 19 billion more base pairs than the previous record holder, the ]marbled lungfish
The marbled lungfish (''Protopterus aethiopicus'') is a lungfish of the family Protopteridae. Also known as the leopard lungfish, it is found in Eastern and Central Africa, as well as the Nile region. At 133 billion base pairs, it has the large ...
, whose 130 billion base pairs weigh in at 132.83 picograms per cell.[ScienceDaily, Rare Japanese plant has largest genome known to science, Royal Botanic Gardens, Kew, October 7, 2010]
/ref> Since then, other organisms have been assayed and reported to have larger genomes; ''Polychaos dubium
''Polychaos dubium'' is a freshwater amoeboid and one of the larger species of single-celled eukaryote. Like other amoebozoans, ''P. dubium'' moves by means of temporary projections called pseudopods. ''P. dubium'' reportedly has one of the larg ...
'' may be the current record holder, but the authors of one study suggest treating that measurement with caution because it was taken before the advent of modern genomic methods.[
]
References
External links
*
*
Rareplants page
{{Taxonbar, from=Q1039615
Melanthiaceae
Endemic flora of Japan
Plants described in 1878