Triantha
Encyclopedia
Triantha is a small genus
of flowering plant
s in the family
Tofieldiaceae
. Triantha has four species
. One of these is endemic to Japan
. The other three are native
to North America
. A comparison of DNA sequence
s has indicated that Triantha glutinosa might be two species.
Before the family Tofieldiaceae was established in 1995, Triantha and related genera were usually placed in Nartheciaceae
, Liliaceae
, or Melanthiaceae
, but molecular phylogenetic studies of monocots and Alismatales
have shown that inclusion of Triantha etc. in these families makes them polyphyletic.
Some authors have included Triantha within the genus Tofieldia
. Triantha is distinguished from Tofieldia by its glandular-pubescent stems and by the presence of seed appendages. In 2011, a study of two nuclear
gene
s and ten chloroplast
genes showed that Triantha and Tofieldia are monophyletic and closely related
sister clade
s. The species of Triantha are so closely related that the authors could not resolve any relationships among them.
Species include:
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...
Tofieldiaceae
Tofieldiaceae
Tofieldiaceae is the botanical name of a family of flowering plants in the monocot order Alismatales. The family is divided into five genera, which together comprise 20 or 21 species. They are small, herbaceous plants, mostly of arctic and subarctic regions, but a few extend further south, and...
. Triantha has four 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...
. One of these is endemic to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The other three are native
Indigenous (ecology)
In biogeography, a species is defined as native to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention. Every natural organism has its own natural range of distribution in which it is regarded as native...
to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. A comparison of 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 has indicated that Triantha glutinosa might be two species.
Before the family Tofieldiaceae was established in 1995, Triantha and related genera were usually placed in Nartheciaceae
Nartheciaceae
Nartheciaceae is a botanical name of a family of flowering plants. Such a family has only rarely been recognized by systems of plant taxonomy.The APG III system does recognize such a family and places it in the order Dioscoreales, in the clade monocots...
, Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
, or Melanthiaceae
Melanthiaceae
Melanthiaceae is a family of flowering perennial herbs in the Northern Hemisphere. The family has been recognized by relatively few taxonomists, and the circumscription has varied...
, but molecular phylogenetic studies of monocots and Alismatales
Alismatales
Alismatales is an order of flowering plants including about 2500 species. Pleants assigned to this order are mostly tropical or aquatic.-Description:...
have shown that inclusion of Triantha etc. in these families makes them polyphyletic.
Some authors have included Triantha within the genus Tofieldia
Tofieldia
Tofieldia is a small genus of flowering plants often classified in the lily family; it is also sometimes included in the newer family Tofieldiaceae. The genus sometimes includes species of genus Triantha. These are rhizomatous perennial herbs with spikes or racemes of lilylike flowers...
. Triantha is distinguished from Tofieldia by its glandular-pubescent stems and by the presence of seed appendages. In 2011, a study of two nuclear
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
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...
s and ten 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...
genes showed that Triantha and Tofieldia are monophyletic and closely related
Phylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...
sister 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. The species of Triantha are so closely related that the authors could not resolve any relationships among them.
Species include:
- Triantha glutinosa - sticky asphodel
- Triantha japonica BakerJohn Gilbert BakerJohn Gilbert Baker was an English botanist.Baker was born in Guisborough, the son of John and Mary Baker and educated at Quaker schools in Ackworth and York....
- Triantha occidentalis -western false asphodel
- Triantha racemosa -coastal false asphodel