Leaf surface images at the middle of the figure, show increased vein density (white parallel bands) in morphologically diverse leaves (see plant images) of closely related species of HHKK, HHJJ, GG, and FF genomes. Numbers, at the top and below these leaf surface images represent the vein number at 2mm space in case of O. schlechteri (one of the high vein density species) and O. sativa IR64. Scale bar under the leaf surface image = 1 mm. Positions of the veins are marked by red stars (*) in the leaf transverse section (TS) at the right, confirmed that the increased vein frequencies are due to reduced inter-veinal distance (IVD). Leaf types (Sw/Sn), mesophyll (MC) types (A/B), and inter-veinal distance (IVD) are indicated. Sw = Short-wide leaves, Sn = Short-narrow leaves.