Sentence:  Cotton stuff mordanted with alumina alone takes an <WSD>amaranth</WSD>, red or violet rose red colour. [...] <WSD>Amaranth</WSD>, red, bluish rose, poppy, and scarlet are the colours prepared by the dyer with ordinary cochineal. Ammoniacal cochineal gives <WSD>amaranth</WSD> colours, and is employed in combination with many other colours. 
Meaning of the word marked with <WSD> tags:  The characteristic purplish-red colour of the flowers or leaves of these plants.