Trochodendron drachuckii
Encyclopedia
Trochodendron drachukii is an extinct species of flowering plant
in the family Trochodendraceae
known from a fossil
fruiting structure
found in the early Ypresian
age Eocene
fossil
s found in British Columbia, Canada. T. drachukii is one of the oldest members of the genus Trochodendron
, which includes the living species T. aralioides
, native to Japan
, southern Korea
and Taiwan
and the coeval extinct species T. nastae
from Washington state
, USA.
Description of the new species by Dr. Kathleen Pigg, Richard Dillhoff, Melanie DeVore and Wesley Wehr
was based on the study of a single complete fruiting structure
specimen. The holotype
fossil
, number "UWBM 97819
", being housed in the Burke Museum of Natural History and Culture
, Seattle, Washington
. They published their 2007 type description of the species in the International Journal of Plant Sciences
volume number 168 and named the species drachuckii in honor of Robert Drachuck in recognition for his finding and donation of the type specimen for study. The holotype was recovered from an Ypresian age unnamed formation outcropping at the McAbee fossil site near Cache Creek, BC
, which is designated the type locality
.
T. drachuckii has been placed in the genus Trochodendron based on the morphology
of the fruiting structure
and overall shape of the fruits. The 11.4 centimetres (4.5 in) long raceme possess 23 distinguishable fruits grouped in twos and threes along the axis. Each fruit is 3–4 mm (0.118110236220472–0.15748031496063 in) by 3–4 mm (0.118110236220472–0.15748031496063 in) and composed of six fused carples
.
Trochodendron shares with Tetracentron the very unusual feature in angiosperms
of lacking vessel element
s in its wood
. This has long been considered a very primitive character, resulting in the classification of these two genera in a basal position in the angiosperms; however, genetic research by the Angiosperm Phylogeny Group
has shown it to be in a less basal position (early in the eudicots), suggesting that the absence of vessel elements is a secondarily evolved character, not a primitive one.
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...
in the family Trochodendraceae
Trochodendraceae
Trochodendraceae is a family of flowering plants with two living genera found in southeast Asia. The two living species share the feature of secondary xylem without vessels, which is quite rare in angiosperms...
known from a fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
fruiting structure
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
found in the early Ypresian
Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....
age Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s found in British Columbia, Canada. T. drachukii is one of the oldest members of the genus Trochodendron
Trochodendron
Trochodendron is a genus of flowering plants with one living species, Trochodendron aralioides, and six extinct species known from the fossil record...
, which includes the living species T. aralioides
Trochodendron aralioides
Trochodendron aralioides, sometimes colloquially called "wheel tree", is a flowering plant and the sole living species in the genus Trochodendron, which also includes several extinct species. It was also often considered the sole species in the family Trochodendraceae, though botanists now include...
, native 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...
, southern Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
and the coeval extinct species T. nastae
Trochodendron nastae
Trochodendron nastae is an extinct species of flowering plant in the family Trochodendraceae known from fossil leaves found in the early Eocene Ypresian stage Klondike Mountain Formation deposits of Northern Washington State. T. nastae is one of the oldest members of the genus Trochodendron, which...
from Washington state
Washington State
Washington State may refer to:* Washington , often referred to as "Washington state" to differentiate it from Washington, D.C., the capital of the United States* Washington State University, a land-grant college in that state- See also :...
, USA.
Description of the new species by Dr. Kathleen Pigg, Richard Dillhoff, Melanie DeVore and Wesley Wehr
Wesley C. Wehr
Wesley Conrad Wehr was an American paleontologist and artist best known for his studies of Tertiary fossil floras in western North America, the Stonerose Interpretive Center, and as a part of the Northwest School of art.-Early life:...
was based on the study of a single complete fruiting structure
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
specimen. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
, number "UWBM 97819
Burke Museum of Natural History and Culture
The Burke Museum of Natural History and Culture has been a Washington state museum since 1899. It is located at the University of Washington campus at the intersection of N.E. 45th Street and 17th Avenue N.E. in Seattle, Washington, USA, in the University District. It is the only major natural...
", being housed in the Burke Museum of Natural History and Culture
Burke Museum of Natural History and Culture
The Burke Museum of Natural History and Culture has been a Washington state museum since 1899. It is located at the University of Washington campus at the intersection of N.E. 45th Street and 17th Avenue N.E. in Seattle, Washington, USA, in the University District. It is the only major natural...
, Seattle, Washington
Seattle, Washington
Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...
. They published their 2007 type description of the species in the International Journal of Plant Sciences
International Journal of Plant Sciences
The International Journal of Plant Sciences covers botanical research including genetics and genomics, developmental and cell biology, biochemistry and physiology, morphology and structure, systematics, plant-microbe interactions, paleobotany, evolution, and ecology. The journal also regularly...
volume number 168 and named the species drachuckii in honor of Robert Drachuck in recognition for his finding and donation of the type specimen for study. The holotype was recovered from an Ypresian age unnamed formation outcropping at the McAbee fossil site near Cache Creek, BC
Cache Creek, British Columbia
Cache Creek is a junction community northeast of Vancouver in British Columbia, Canada. It is on the Trans-Canada Highway in the province of British Columbia at its junction with northbound Highway 97...
, which is designated the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
.
T. drachuckii has been placed in the genus Trochodendron based on the morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
of the fruiting structure
and overall shape of the fruits. The 11.4 centimetres (4.5 in) long raceme possess 23 distinguishable fruits grouped in twos and threes along the axis. Each fruit is 3–4 mm (0.118110236220472–0.15748031496063 in) by 3–4 mm (0.118110236220472–0.15748031496063 in) and composed of six fused carples
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...
.
Trochodendron shares with Tetracentron the very unusual feature in angiosperms
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...
of lacking vessel element
Vessel element
A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers....
s in its wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
. This has long been considered a very primitive character, resulting in the classification of these two genera in a basal position in the angiosperms; however, genetic research 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...
has shown it to be in a less basal position (early in the eudicots), suggesting that the absence of vessel elements is a secondarily evolved character, not a primitive one.