Planera

Planera is a genus of flowering plants with a single living species, Planera aquatica, the planertree or water elm. The genus has an extensive fossil record dating back to the Cretaceous and spanning the northern hemisphere, with a few southern hemisphere records as well. The living species is found in the southeastern United States, it is a small deciduous tree 10–15 m (390–590 in) tall, closely related to the elms but with a softly, prickly nut 10–15 mm (0.39–0.59 in) 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.

Planera
Planera aquatica
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Rosales
Family:	Ulmaceae
Genus:	Planera J.F.Gmel.
Species
See text

Species

• Planera aquatica

Fossil species

• †Planera antiqua Heer, 1883 (Santonian-Campanian; Paatuut Formation, Greenland)
• †Planera aquaticiformis Hollick, 1936 (Paleocene/Eocene; "Berg Lake flora", Alaska)
• †Planera australis Ettingshausen, 1887 (Late Cretaceous; Otago, New Zealand)
• †Planera chankaensis Pavlyutkin, 2005 (Miocene; Novokachalinsk, Russia)
• †Planera crenata Newberry, 1883 (jr homonym, replacement name P. lingualis)
• †Planera cretacea Berry, 1907 (Cretaceous; North Carolina)
• †Planera dubia Lesquereux, 1859 (Eocene, Chuckanut Formation, Washington)
• †Planera emarginata (Göppert) Heer, 1856 (Tortonian, Poland)
• †Planera ezoana Ôishi & Huzioka, 1954 (Eocene; Hokkaido, Japan)
• †Planera hebridica Simpson, 1961 ("Cenozoic"; Isle of Mull, Scotland)
• †Planera knowltoniana Newberry, 1896 (Cenomanian; Raritan Formation, Virginia)
• †Planera mullensis Simpson, 1961 ("Cenozoic"; Isle of Mull, Scotland)
• †Planera myricifolia (Lesquereux) Cockerell, 1908 (Priabonian; Florissant Formation, Colorado)
• †Planera parvula Saporta, 1888 (Oligocene; France)
• †Planera subkeaki (Rérolle) Saporta, 1888 (Tortonian; La Cerdagnya, France)
• †Planera thompsoniana Traverse, 1955 (Burdigalian; Brandon lignite, Vermont)
• †Planera ulmifolia Schloemer-Jäger, 1958 (Paleocene; Brøgger peninsula, Spitsbergen)
• †Planera variabilis Newberry, 1883 (Ypresian; Green River Formation, Wyoming)

Species formerly included in Planera

• †Abelicea ungeri (Kováts ex Ettingshausen) Holmboe
• †Cedrelospermum nervosum (Newberry) Manchester
• †Chaetoptelea microphylla (Newberry) Hickey
• †Fagopsis longifolia Lesquereux