Sterile species and fertile hybrids of Japanese knotweeds along the river Kelvin.

Fallopia japonica var. japonica, F. sachalinensis and their hybrid F. x bohemica occur along the River Kelvin in Glasgow. We describe their distribution along the river and in the surrounding area. All three taxa are gynodioecious, and in the Glasgow area we found only male sterile plants of F. japonica var. japonica and F. sachalinensis. Due to the absence of male fertile individuals of the parental taxa, we conclude that it is unlikely that the hybrid has arisen in situ.