Effective temperature of the stars as a function of the Rossby number. The colour of the symbol corresponds to the fraction of poloidal field, and the size to the average surface magnetic field strength. The rotated fletches show the percentage of axisymmetric field in the map. For individual stars, variations of axisymmetry between different epochs are visually most clearly presented, but variations in the magnetic field strength can also in principle be seen as differences in the sizes of overplotted circles and variations in the poloidal fraction in their blended colours. In addition to our results from Table 4, there is one additional BE Cet data point and four χ¹ Ori data points from Rosén et al. (2016), and one HD 29615 data point from Hackman et al. (2016). See Sect. 5 for more details.