Quoting from the George Schmid book, The Genus Hosta
"Variability in Veining Count. As with other diagnostic features, a given cultivar displays some variability in the number of veins, and so the count given in the description is the average maximum number of principal veins normally seen
in that cultivar. Occasionally, this number may be exceeded by one or two, while the younger summer leaves may produce fewer veins. It is best to make a count on several mature vernal leaves and then take the average.
Abbreviated Veins. One significant point must be made. The outermost vein or veins are often abbreviated and do not extend to the leaf tip but usually terminate at the leaf margin between a third and halfway from the petiole intersection. Although these veins end at the margin and thus incomplete, they must be counted.
In some cases they are hard to detect on the upper side of the leaf so it is helpful to search for them on the underside, where they are typically more prominent."
