Fig. 3

The 17 planar tilings. Each elementary cell represents an hypercolumn with a pinwheel at its center. The colored edges represent a coarse preferred orientation domain. The names of the five biologically plausible tilings are highlighted in red and a more accurate representation is shown on the right. The names of the tilings (and the associated wallpaper groups) are the shortened crystallographic notations; see [27]. pmm, cmm, and p3m1 are those that best agree with the experimental data