''Trema'' 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 nom ...

of about 15 species of

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

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 closely related to the hackberries (''

Celtis ''Celtis'' is a genus of about 60–70 species of deciduous trees, commonly known as hackberries or nettle trees, widespread in warm temperate regions of the Northern Hemisphere. The genus is part of the extended hemp family (Cannabaceae). ...

''), occurring in subtropical and tropical regions of southern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

, northern

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologi ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, South and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, and parts of North America. They are generally small trees, reaching tall.

Taxonomy

Previously included either in the

elm Elms are deciduous and semi-deciduous trees comprising the flowering plant genus ''Ulmus'' in the plant family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North ...

family,

Ulmaceae The Ulmaceae () are a family of flowering plants that includes the elms (genus ''Ulmus''), and the zelkovas (genus ''Zelkova''). Members of the family are widely distributed throughout the north temperate zone, and have a scattered distribution ...

, or with ''Celtis'' in the Celtidaceae, genetic analysis has shown the Celtidaceae are best placed in the hemp family,

Cannabaceae Cannabaceae is a small family of flowering plants, known as the hemp family. As now circumscribed, the family includes about 170 species grouped in about 11 genera, including ''Cannabis'' (hemp), '' Humulus'' (hops) and '' Celtis'' (hackberries ...

Description

The leaves are alternate, simple, long, ovate-acuminate to lanceolate with a long pointed tip, and evenly serrated margins. 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 particu ...

is a small drupe in diameter.

Species associations

''Trema'' species are sometimes used as food plants by the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e of hepialid

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

s of the genera ''

Aenetus ''Aenetus'' is a genus of moths of the family Hepialidae. There are 24 described species found in Indonesia, New Guinea, New Caledonia, Australia and New Zealand. Most species have green or blue forewings and reddish hindwings, but some are predomi ...

'', including ''A. splendens'', which burrow horizontally into the trunk then vertically down, and ''

Endoclita ''Endoclita'' is a genus of moths of the family Hepialidae. There are 60 described species found in eastern and southeast Asia and the Indian subcontinent. Species *'' Endoclita aboe'' – India *''Endoclita absurdus'' – China *''Endoclita ...

'', including ''E. malabaricus''. Some ''Trema'' species unusually able to live in symbiosis with rhizobia for nitrogen fixation as a non-legume. In this case it is customary to mention these species as a separate genus ''Parasponia''.

Uses

Trema orientalis ''Trema orientale'' (sometimes spelled ''Trema orientalis'') is a species of flowering tree in the hemp family, Cannabaceae. The basionym of ''T. orientalis'', ''Celtis orientalis'' was originally described and published in ''Species P ...

'' is widely planted for land reclamation in southern Asia, valued for its tolerance of poor soils due to its ability to fix

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

. It is also an invasive species on some

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

islands. Image:Bark I IMG 3300.jpg, Bark of '' T. orientalis'' at Kolkata, West Bengal, India File:Trema orientalis (Pigeon Wood) W IMG 2236.jpg, Flowers of ''T. orientalis'' in

Goa Goa () is a state on the southwestern coast of India within the Konkan region, geographically separated from the Deccan highlands by the Western Ghats. It is located between the Indian states of Maharashtra to the north and Karnataka to the ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. File:Trema orientalis (Pigeon Wood) W2 IMG 2237.jpg, Leaves of ''T. orientalis'' in

. File:Trema orientalis (Pigeon Wood) W2 IMG 2236.jpg, Flowers of ''T. orientalis'' in

. Image:Branches I IMG 3304.jpg, Branches of ''T. orientalis'' at Kolkata, West Bengal, India

Species

''Trema'' comprises the following species: * '' Trema affinis'' (Planch.) Blume * '' Trema amboinensis'' (Willd.) Blume * '' Trema andersonii'' (Planch.) Byng & Christenh. * '' Trema angustifolium'' (Planch.) Blume * '' Trema asperum'' (Brongn.) Blume * ''

Trema cannabina ''Trema cannabina'' is a tree found in Southeast Asia and Oceania. They are perennial. It is found in sandy, well drained soil. It also goes by the names of lesser ''Trema'' and poison peach, and in the Samoan language. The plant may release an ...

'' Lour. – Lesser trema * '' Trema cubense'' Urb. * '' Trema discolor'' (Brongniart) Blume * '' Trema domingense'' Urb. * '' Trema eurhynchum'' (Miq.) Byng & Christenh. * '' Trema integerrima'' (Beurl.) Standl. * '' Trema lamarckianum'' (Roem. & Schult.) Blume – West Indian trema, Lamarck's trema * '' Trema levigatum'' Hand.-Mazz. * '' Trema melastomatifolium'' (J.J.Sm.) Byng & Christenh. * '' Trema micranthum'' (L.) Blume – Jamaican nettle tree * '' Trema nitidum'' C.J. Chen * '' Trema orientale'' (L.) Blume – Pigeon wood * '' Trema parviflorum'' (Miq.) Byng & Christenh. * '' Trema politorium'' (Planch.) Blume * '' Trema simulans'' (Merr. & L.M.Perry) Byng & Christenh. * '' Trema tomentosum'' (Roxb.) H.Hara – Poison peach ** var. ''tomentosum'' (Roxb.) H.Hara ** var. ''viridis'' (Planch.) Hewson – eastern Australia * '' Trema vieillardii'' (Planch.) Schltr.

Species names with uncertain taxonomic status

The status of the following species is unresolved: * ''Parasponia paucinervia'' Merr. & L.M.Perry * ''Parasponia rugosa'' Blume * ''Parasponia similis'' Blume * ''Trema acuminatissima'' Boerl. * ''Trema argentea'' Blume * ''Trema blancoi'' Blume * ''Trema bracteolata'' Blume * ''Trema burmanni'' Blume * ''Trema carinata'' Blume * ''Trema crassifolia'' Liebm. * ''Trema glabrescens'' Blume * ''Trema glomerata'' Blume * ''Trema griffithii'' Blume * ''Trema guinensis'' Priemer * ''Trema humbertii'' J.-F.Leroy * ''Trema imbricata'' Blume * ''Trema integrifolia'' Baill. * ''Trema integrifolia'' Hosok. * ''Trema lancifolia'' Ridl. * ''Trema malaccensis'' Gand. * ''Trema morifolia'' Blume * ''Trema pallida'' Blume * ''Trema philippinensis'' Elmer * ''Trema pubigera'' Blume * ''Trema rigida'' Blume * ''Trema rugosa'' Blume * ''Trema scaberrima'' Blume * ''Trema sieberi'' Blume * ''Trema strigilosa'' Lundell * ''Trema strigosa'' Blume * ''Trema viridis'' Blume * ''Trema vulcanica'' Merr.

References

External links

Pacific Island Ecosystems at Risk (PIER) page on ''Trema orientalis'' (with photos)
{{Taxonbar, from=Q945999 Rosales genera