Lateral vein angle

(Not applicable to leaves with longitudinally parallel venation, leaves with no lateral veins or leaves with midrib absent. Leaflets should be used in compound leaves.)

This is the angle between the midrib and the lateral vein, measured from the midrib, on the leaf blade (or leaflet blade in the case of compound leaves). A special technique is used for curved lateral veins. The vein angle is measured in the following way.  Decide which lateral vein to study.  Go to the next vein above and draw a line from its base and at right angles to the midrib until it intersects the vein in question.  Draw a line from this point to the base of the vein in question.  The vein angle is the angle between this line and the midrib. (fig showing how to measure angle)