Acer circinatum, second of a three-part series on this plant. The first can be seen here. The last of the series will include a written piece about the whys and hows of autumn leaf colours.
Botany / conservation resource link: H. Bruce Rinker's article entitled, “The Weight of a Petal: The Value of Botanical Gardens”. An excellent (but brief) article summarizing the benefits of research and conservation gardens, such as UBC.