Aims Root tensile tests are often rejected if failure location is outside the middle section of samples. This study aims to identify where and why failure occurs along a root axis, and hence to revisit current approaches to test-validity. Methods Roots from Festuca arundinacea; Lolium multiflorum; Lolium perenne were sampled from field-grown plants. Roots were tensile tested using a universal testing machine. Root samples were...