Bedstraw stem. Coloured scanning electron micrograph (SEM) of the stem of bedstraw (Galium sp.). The bedstraws are sweet-smelling herbaceous plants of the Rubiaceae family, which includes coffee, madders and wild quinine. They curdle milk and so were used historically in cheese- making, as well as for medicinal purposes. Magnification: x54 at 6x7cm size.