''Eucommia'' is a genus of small

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 ...

s now native to China, with a fossil record that shows a much wider distribution. The single living species, '' Eucommia ulmoides'', is near threatened in the wild, but is widely cultivated in China for its

bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...

, and is highly valued in herbology such as

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logica ...

Description

Modern ''Eucommia'' trees grow to about 15 m tall. The leaves are

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 ...

, arranged alternately, simple ovate with an acuminate tip, long, and with a serrated margin. If a leaf is torn across, strands of

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well. In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosper ...

exude from the leaf veins and solidify into

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, a ...

and hold the two parts of the leaf together. It flowers from March to May with 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 being inconspicuous, small, and greenish. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

s ripen between June and November and are a winged

samara Samara ( rus, Сама́ра, p=sɐˈmarə), known from 1935 to 1991 as Kuybyshev (; ), is the largest city and administrative centre of Samara Oblast. The city is located at the confluence of the Volga and the Samara rivers, with a population ...

with one

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...

, very similar to an elm samara in appearance. The modern fruits are long and broad, while fruits of the extinct species range up to long. ''Eucommia'' is

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproducti ...

, with separate male and female plants.

Taxonomy

''Eucommia'' is the sole member of the family Eucommiaceae, and was formerly considered to be a separate order, the Eucommiales. The modern species is sometimes known as the "hard rubber tree", "Gutta-percha tree" or "Chinese rubber tree", but is not related to either the true

Gutta-percha Gutta-percha is a tree of the genus '' Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly fro ...

tree of southeastern Asia, nor to the South American rubber tree. *''Eucommia'' **†'' Eucommia constans'' (Miocene-Pliocene; Mexico) **†'' Eucommia eocenica'' (Middle Eocene; Mississippi Embayment) **†'' Eucommia europaea'' (Oligocene; Europe) **†'' Eucommia jeffersonensis'' (latest Eocene; Oregon) **†'' Eucommia montana'' (Early-Late Eocene; western North America) **†'' Eucommia rolandii'' (Early-Middle Eocene; Mississippi and British Columbia) **'' Eucommia ulmoides'' (Living, central-eastern China)

Distribution

''E. ulmoides'' is native to forest areas on hills and mountains of the provinces in central and eastern China, though it has been suggested that the species is extinct in the wild. ''E. ulmoides'' is also occasionally planted in

botanical garden A botanical garden or botanic gardenThe terms ''botanic'' and ''botanical'' and ''garden'' or ''gardens'' are used more-or-less interchangeably, although the word ''botanic'' is generally reserved for the earlier, more traditional gardens, an ...

s and other

garden A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...

s in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

, North America, and elsewhere, being of interest as the only cold-tolerant (to at least -30 °C) rubber-producing tree.

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 ...

species of ''Eucommia'' have been found in 10- to 35-million-year-old brown coal deposits in central

, in numerous fossil sites in Asia, and five different fossil species have been described from North America, indicating the genus had a much wider range in the past.

References

External links

{{Taxonbar, from=Q5406185 Garryales Asterid genera Trees of China Near threatened plants Taxa named by Daniel Oliver