I've always admired these sorts of illustrations. Botanical ones too. Please forgive the newb questions, but does this gorgeous illustration style have a name and how was it done (I.e., what is the medium -- some kind of colored ink?)
I hate to be a contrarian, but I've always hated them. IMHO, the extra-fancy-style illustrations are just that. Now that we have wildlife photography, these seem to regress and appear much worse (again, IMHO) because they are literally an illustration of reality and not a snapshot: https://www.youtube.com/watch?v=NwhVJ7cv9B4&t=36s
Natural science illustration returns reasonable results. I think most are done traditionally in some type of watercolors.