Model of Polygonum (Knotweed) made by Robert and Reinhold Brendel, Berlin, 1875-1900. Polychrome papier mache on turned boxwood stands.

Robert Brendel (c. 1821–1898) and his son, Reinhold (c. 1861–1927) were didactic model makers based in Berlin at the end of the nineteenth century. They supplied papier-mâché models to universities, colleges and schools for teaching throughout Europe and the wider world. This particular example shows the flower and seed of the knotweed, enabling students to learn how the plant reproduces.