First establish how many orders of pinnules (primary, secondary, tertiary, etc.) are present.

Then, score the following characters on the smallest (highest order) leaflet or pinnule. Identify which is the highest order of leaflet (pinna or pinnule); i.e. the smallest element of leaf-blade that is not continuous with any of the adjacent leaflets, and score the following characters on these, making certain the pinnule you select is not atypical.