Seeds of the different investigated plant species and accessions sorted by seed mass. The blue lines represent seed mass (M), red crosses denote measured volume (V), and green circles represent volume calculated from length and width of projection (V2D). For better readability, both V and V2D were scaled by the slopes of linear regressions to meet the range of M. A to C, Rapeseed accessions Wotan (A), Expert (B), and Pirola (C). D to F, Barley accessions Barke (D), HOR13719 (E), and HOR9707 (F). G to I, Arabidopsis accessions Col-0 (G), Lag2-2 (H), and Agu-1 (I).