Dipteronia

They are deciduous flowering shrubs or small trees, reaching 10–15 m (33–49 ft) tall. The leaf arrangement is opposite and pinnate with between 7 - 15 leaflets on each leaf.^[2] The inflorescences are paniculate, terminal or axillary. The flowers have five sepals and petals; staminate flowers have eight stamens, 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.^{[citation needed]}

There are only two living species, Dipteronia sinensis and Dipteronia dyeriana; both are endemic to mainland China.^[3] Dipteronia dyeriana is listed by the IUCN as being a "Red List" threatened species, and known from only five isolated populations in south-eastern Yunnan Province.^[3]

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.^[4] 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^[5] of the Bridge Creek Flora in the upper John Day Formation.^[2] Concurrently, several Dipteronia brownii fruits have also been collected from Rupelian 32 ± 1 million years ago lacustrine mudstones in Chuxiong Yi Autonomous Prefecture southwestern China.^[6]

Media related to Dipteronia at Wikimedia Commons