Dipteronia is a genus with two living and one extinct species in the soapberry family Sapindaceae. The living species are native to central and southern China. The fossil species has been found in Middle Paleocene to Early Oligocene sediments of North America and China.
Classification
Older classifications segregated the
Maple (
Acer) and
Dipteronia into the family
Aceraceae, however work by the Angiosperm Phylogeny Group (
APG system onward) and related investigations
led to the subsuming of Acereae into Sapindaceae as the tribe Acereae.
Dipteronia is considered to be the sister genus to
Acer.
Description
They are
deciduous flowering
or small
, reaching tall. The
leaf arrangement is opposite and
pinnate with between 7 - 15 leaflets on each leaf.
The
are paniculate, terminal or axillary. The
have five
and
; staminate flowers have eight
, and bisexual flowers have a two-celled ovary. The
fruit is a rounded samara containing two compressed nutlets, flat, encircled by a broad wing which turns from light green to red with ripening.
The name Dipteronia stems from the Greek "di-" (two, both) & "pteron" (wings), from the winged fruits with wings on both sides of the seed.
There are only two living species, Dipteronia sinensis and Dipteronia dyeriana; both are endemic to mainland China.
Fossil record
The extinct species
Dipteronia brownii is known from
Middle Paleocene to
Early Oligocene sites across western North America. The oldest fossils are found in the Fort Union Formation of Wyoming and the Tsagayan Formation of Northeastern coastal Russia.
In the Early Eocene the species expanded northward to the Eocene Okanagan Highlands sites such as the Klondike Mountain Formation of Washington, Driftwood Shales and Tranquille Formation of
British Columbia as well as into the John Day Formation of central Oregon. During the middle to late Eocene the species spread east and south to the Ruby Basin Flora of Montana and the Florissant Formation of Colorado, while the last occurrences are in the Early Oligocene, Rupelian
of the Bridge Creek Flora in the upper John Day Formation.
Concurrently, several
Dipteronia brownii fruits have also been collected from
Rupelian lacustrine in Chuxiong Yi Autonomous Prefecture southwestern
China.
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