L22 three-veined The leaf has a midrib or main central longitudinal vein and two main veins (of similar thickness) running more or less parallel to the margin of the leaf blade but some distance from it. The two main lateral veins may approximate the midrib in thickness and extend halfway up the leaf blade or approach the apex.

L23 none either side of midrib

L24 up to 7 on each side of the midrib

L25 8 - 20 on each side of the midrib

L26 more than 20 on each side of the midrib

L27 longitudinally parallel

L28 other type of venation Vein arrangements which do not fit any of the previous categories.