Linked from
The 7 pages that link to Alizarin, each with the reason it gives.
Natural dyeBroader topic: Alizarin is the principal historic red colorant associated with madder.
AnthraceneRelated: Its synthesis from anthracene helped make the hydrocarbon industrially valuable.
ScarletRelated: Synthetic alizarin changed the economics of red dyes, including shades near scarlet.
Rubia tinctorumRelated: It is the principal red colorant associated with the plant’s dyeing use.