Figure 8 from: Harris AJ, Chen Y, Olsen RT, Lutz S, Wen J (2017) On merging Acer sections Rubra and Hyptiocarpa: Molecular and morphological evidence. PhytoKeys 86: 9-42. https://doi.org/10.3897/phytokeys.86.13532

Figure 8 - Elongate leaf shape in Acer rubrum and A. pycnanthum. A–B A. rubrum C–D A. pycnanthum. Unfortunately, there is no scale for the images of A. pycnanthum, but the leaf size is similar to that illustrated in Figure 1B. Herbarium specimens in A and B 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/).