Planera aquatica
{{Short description|Species of flowering plants}}
{{Italic title}}
{{Speciesbox
|name = Water elm
|image = NAS-130y Planera aquatica.png
|status = LC
|status_system = IUCN3.1
|genus = Planera
|species = aquatica
|range_map = Planera aquatica range map.jpg
|range_map_caption = Natural range of the water elm
}}
Planera aquatica,{{cite web |title=Search results for Planera|work=The Plant List |url=http://www.theplantlist.org/tpl1.1/search?q=Planera |accessdate=1 March 2016 }} the planertree{{PLANTS|id=PLAQ|taxon=Planera aquatica|accessdate=7 October 2015}} or water elm, is a species of flowering plant. Found in the southeastern United States, it is a small deciduous tree 10–15 m tall, closely related to the elms but with a softly, prickly nut 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, 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.{{cite web|url=http://dendro.cnre.vt.edu/dendrology/syllabus/factsheet.cfm?ID=347|title=Water Elm Ulmaceae Planera aquatica J.F. Gmel.|publisher=Virginia Tech Department of Forestry and Environmental Conservation|accessdate=December 15, 2014}}
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.{{Cite book|last=Kirkman, L. Katherine.|url=https://www.worldcat.org/oclc/69792028|title=Native trees of the Southeast|date=2007|publisher=Timber Press|others=Brown, Claud L., 1925-, Leopold, Donald Joseph, 1956-|isbn=978-0-88192-828-0|location=Portland, Or.|oclc=69792028}} 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.{{Cite web|title=Planera aquatica (Water Elm) {{!}} North Carolina Extension Gardener Plant Toolbox|url=https://plants.ces.ncsu.edu/plants/planera-aquatica/|access-date=2020-11-02|website=plants.ces.ncsu.edu}}
- 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 (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
{{Reflist}}
{{Taxonbar|from=Q14643457}}
Category:Taxa named by Johann Friedrich Gmelin
{{Ulmaceae-stub}}