Width is measured at the widest part of the blade. This applies in particular for those species such as H. auriculata where the widest part of the blade is at the apex.

Width of leaves has been taken for mature leaves and may not fully encompass those found in juvenile stages, since these were not always available. For example it is known that the juvenile leaves of H. florida are wider than the mature leaves, but only the mature leaves are scored here for the sake of consistency of comparisons.