''Cyclocarya'' is a

genus 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 n ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

s in the family

Juglandaceae The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia. The nine or ten genera in the family have ...

, comprising a single species ''Cyclocarya paliurus'' (qing qian liu or wheel wingnut), formerly treated in the genus '' Pterocarya'' as ''Pterocarya paliurus''. It is native to eastern and central China.Flora of China
''Cyclocarya''
/ref>Flora of China
''Cyclocarya paliurus''
/ref> It is a

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, a ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

growing to 30 m tall. The foliage is similar to ''Pterocarya'', with pinnate leaves 20–25 cm long with five to eleven leaflets, the terminal leaflet present; the leaflets are 5–14 cm long and 2–6 cm broad. 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 mechanism ...

s are

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). They contain many, usually unisexual flowers, arra ...

s; the male (pollen) catkins are produced in clusters (not singly as in ''Pterocarya''), the female catkins 25–30 cm long at maturity, bearing several small winged

nuts Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Com ...

with a circular wing 2.5–6 cm diameter right round the nut (instead of two wings at the sides as in ''Pterocarya'').

Fossil record

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

endocarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. A ...

s of †''Cyclocarya nemejcii'' from the early

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

, have been found in the Kristina Mine at Hrádek nad Nisou in

North Bohemia North Bohemia ( cs, Severní Čechy, german: Nordböhmen) is a region in the north of the Czech Republic. Location North Bohemia roughly covers the present-day NUTS regional unit of ''CZ04 Severozápad'' and the western part of ''CZ05 Severový ...

, the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. Th ...

. Described first from the Middle Miocene of Japan †''Cyclocarya ezoana'' is also known from the Middle Miocene Seldovia Point Flora of

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

. 10 Ma old

leaflets that are very similar to it have been found in Tröllatunga-Gautshamar Formation in

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...

. The Icelandic fossils and †''C. ezoana'' are similarb to †''C. cyclocarpa'' from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was p ...

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

.Late Cainozoic Floras of Iceland: 15 Million Years of Vegetation and Climate History in the Northern North Atlantic by Thomas Denk, Friðgeir Grimsson, Reinhard Zetter and Leifur A. Símonarson - Springer Science & Business Media, 28. mar. 2011 - 854 pages

Gallery

Cyclocarya paliurus IMG 2983.jpg, ''Cyclocarya paliurus'' in the Dresden Botanical Garden Cyclocarya paliurus seeds, by Omar Hoftun.jpg, Winged nutlets

References

Juglandinae Monotypic Fagales genera Flora of China {{Fagales-stub