I thought that "Yang Xiao-Long" could also be a shortened version of "Baiyang Xiao-Long" which means "Little Poplar dragon," and that she was named after the pale, yellowish Poplar wood. This other translation makes more sense, though.

And since Blake also has the last name "Belladonna" which is a plant that grows black, poisonous berries, she has two different sources of "black" in her name.

Never knew that on Yang. I know that Belladonna was named after the deadly nightshade, but I never knew they produce black berries.