Late-season specimens of Acer sect. Rubrum approaching leaf senescence. A A. pycnanthum with black arrow indicating silvery abaxial surface and green arrow indicating non- silvery surface. The inset in the upper left shows an SEM micrograph of a portion of an abaxial leaf surface from this specimen that lacks the silvery color such as the area referred to by the green arrow. Blue scale bar = 50μm. For an SEM micrograph showing a silvery portion of leaf surface from this specimen, see Figure 5CB A. rubrum exhibiting exclusively silvery abaxial leaf surface (upper, right leaf). The inset in the upper left shows an SEM micrograph of a portion of an abaxial leaf surface from this specimen bearing the characteristic silvery surface, and we did not observe late season leaves of A. rubrum lacking the silvery surface. Herbarium specimens deposited at US, and accession information visible in images. Detailed specimen records are available via the US online catalog (http://collections.nmnh.si.edu/search/botany/).