藍 - indigo

dyer's knotweed (Persicaria tinctoria, used to produce indigo dye)

pupil excelling his master

indigo

blue-collar; blue-collar worker (employee)

indigo

indigo

surpassing one's master

little spinefoot (Siganus spinus); black spinefoot; black trevally; blue-spotted trevally; spiny rabbitfish

anil indigo (Indigofera suffruticosa)

ukiyo-e print produced with various shades of indigo (and sometimes small amounts of vermilion or yellow)

blue-green bacterium; cyanobacteria; cyanobacterium

dyeing poison dart frog (Dendrobates tinctorius)