There is a link to the USDA Wood Handbook in my tagline. In addition to good descriptions of different species of wood, it has low magnification (approximately 15x) micrograph photos of each types cross section. As the book states, the colors in the images are a result of dyes to used to make the cell structure more visible and not representative of the the wood type.
A 'toy-store' grade microscope (or low end ones on ebay, some with digital cameras built in) would go a long way in 'confirming' the general physical interpretations of density, hardness, color, scent, etc.
Good luck in your quest for details.
wbh1963 is flowing with the grain in Arlington, Washington, USA
A day without curls is like a day without sunshine!