Fig. 3.

Visualizing common features and differences between written and oral knowledge on the indications of medicinal plants. Plant names are marked with a “b” and “s” indicating indications taken from books and students’ indications respectively a Primary component analysis and b heat-map analysis show common features between written (literature) and oral knowledge in plants like Calendula officinalis L. or Cetraria islandica L. Divergent indications are e.g., observed for Salvia officinalis L. Red indicates a high percentage of either knowledge or usage, blue a low percentage of knowledge