''Planera'' 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 ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s with a single species, ''Planera aquatica'', the planertree or water elm. Found in the southeastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

, it is a small

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, ...

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 ...

10–15 m tall, closely related to 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 ...

s but with a softly, prickly

nut 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 Co ...

10–15 mm diameter, instead of a winged seed. It grows, as the name suggests, on wet sites. Despite its common English name, this species is not a true elm, although it is a close relative of the elms (species of the genus ''Ulmus''). It is also subject to

Dutch elm disease Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into Americas, America ...

, a disease which affects only members of the Ulmaceae. It is native to most of the southeast United States. It is hardy down to Zone 7.

Water Elm

Description

File:Water Elm, Planera aquatica, Bark.jpg, Bark File:Planera aquatica, Water Elm, Leaves.jpg, Leaves File:Planera aquatica, Water Elm. Underside of leaf.jpg, Leaf underside displaying pubescence File:Water Elm, Planera aquatica, fruit.jpg, Fruit with and without shell * Leaves: alternate, 3–7 cm long, with irregularly serrated to double serrated margins. Leaf base wedge-shaped or rounded. Leaf base often equal and symmetrical, but can be asymmetrical. Thin pubescent hair is often present on underside of leaf. * Bark: gray-brown, thin, some flaky loose scales. Exfoliates to reveal red-brown area under bark. * Fruit: a drupe. Has a green shell that turns brown with age. Matures April - May.

Distinguishing Characteristics

While often confused with true elms, it can be easily distinguished by noticing the fruit are drupes and not samaras. When fruit are not in season, the flaky bark is unique to water elm and not characteristic of true elms. May also be confused with ''

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). ...

'' (hackberries), but hackberry leaves have pronounced lower lateral veins not found on water elm.

Ecology

Typically found on alluvial floodplains subjected to seasonal or temporary flooding. Often found in swamps, streams, lakes, or in riparian areas. Has some wildlife value, food for bees and some bird species. Prefers sandy or gravelly, moist soils. Classified as an obligate wetland plant (OBL).

References

Ulmaceae Monotypic Rosales genera Taxa named by Johann Friedrich Gmelin {{Ulmaceae-stub