x Reyllopia conollyana: a hybrid between two non-native Fallopia species
Fallopia japonica has been known to form a hybrid with Fallopia baldschuanica (Polygonaceae – both EPPO List of IAP) within the EPPO region since seed was collected in Wales (GB) that resulted in the development of the hybrid in 1983. The hybrid was named Fallopia x conollyana (later renamed x Reyllopia conollyana). The hybrid is formed from an ovule of F. japonica and pollen from F. baldschuanica. In 1986, an established hybrid was identified on waste ground by a railway in the county of Middlesex (England) and the only other specimen found in the United Kingdom was identified in 2002 from Northamptonshire (England). The hybrid has also been recorded in the environment in Germany, Hungary and Norway, and grown from seed of Fallopia japonica collected in the Czech Republic and Belgium. In 2016, x Reyllopia conollyana were recorded from two localities in Belgium as established plants. The first observed on a talus slope (scree) in Izegem in 2016 and later in the same year alongside a railway track near Ghent. Unlike the maternal plant, x Reyllopia conollyana has a woody stem, although it has rhizomes and scarcely climbing stems with an intermediate leaf shape.
Sources
Hoste I, Verloove F, Bailey J (2017) Two recent records from Belgium of established plants of Fallopia ×conollyana: A low profile alien steps into the open. Dumortiera 112, 8-13.
Bailey JP (2001) Fallopia × conollyana: The railway-yard knotweed. Watsonia 23, 539-541.