Inflorescences of Acer sects. Rubra and Hyptiocarpa. A Acer rubrum with umbels of pistilate flowers B Acer rubrum with umbels of staminate flowers C A. pycnanthum with umbels of pistilate flowers C A. saccharinum with umbels of pistilate flowers. Note flowers with two, divided persistent styles D A. pinnatinervium with racemose thyrse. Specimens in A–D deposited at US, and specimen in D deposited at the British National Museum (BM). Accession information visible in images, and detailed specimen records are available via the US online catalog (http://collections.nmnh.si.edu/search/botany/) and at the data portal of BM (http://data.nhm.ac.uk/).