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 tall, closely related to the elms but with a softly, prickly nut 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.

Species

• Planera aquatica

Fossil species

• †Planera antiqua (Santonian-Campanian; Paatuut Formation, Greenland)
• †Planera aquaticiformis (Paleocene/Eocene; "Berg Lake flora", Alaska)
• †Planera australis (Late Cretaceous; Otago, New Zealand)
• †Planera chankaensis (Miocene; Novokachalinsk, Russia)
• †Planera crenata (jr homonym, replacement name P. lingualis)
• †Planera cretacea (Cretaceous; North Carolina)
• †Planera dubia (Eocene, Chuckanut Formation, Washington)
• †Planera emarginata (Tortonian, Poland)
• †Planera ezoana (Eocene; Hokkaido, Japan)
• †Planera hebridica ("Cenozoic"; Isle of Mull, Scotland)
• †Planera knowltoniana (Cenomanian; Raritan Formation, Virginia)
• †Planera mullensis ("Cenozoic"; Isle of Mull, Scotland)
• †Planera myricifolia (Priabonian; Florissant Formation, Colorado)
• †Planera parvula (Oligocene; France)
• †Planera subkeaki (Tortonian; La Cerdagnya, France)
• †Planera thompsoniana (Burdigalian; Brandon lignite, Vermont)
• †Planera ulmifolia (Paleocene; Brøgger peninsula, Spitsbergen)
• †Planera variabilis (Ypresian; Green River Formation, Wyoming)

Species formerly included in Planera

• †Abelicea ungeri
• †Cedrelospermum nervosum
• †Chaetoptelea microphylla
• †Fagopsis longifolia

References