Wikipedia
Rhodotypos scandens, the sole species of the genus Rhodotypos, is a deciduous shrub in the family Rosaceae, closely related to Kerria and included in that genus by some botanists. It is native to China, possibly also Japan.
It grows to 2-5 m tall, with (unusually for a species in the Rosaceae) opposite (not alternate) leaves, simple ovate-acute, 3-6 cm long and 2-4 cm broad with a serrated margin. The flowers are white, 3-4 cm diameter, and (also unusually) have four (not five) petals; flowering is from late spring to mid-summer. The fruit is a cluster of 1-4 shiny black drupes 5-8 mm diameter.
It does not have a widely used English name, most commonly being known by its genus name rhodotypos, also occasionally as jetbead or jet-bead. It is an invasive species in some parts of eastern North America.