Two plants of the borage family are called alkanet and there is some confusion in the literature as to which is which. Alkanna tinctoria is the true alkanet, and its roots produce a purple dye used in textiles and soap - read more about alkanet here...
3. False Alkanet (Anchusa officinalis)
This plant is also known as Common Bugloss or Common Anchusa and is a perennial plant of the Borage family like true Alkanet.
It grows to nearly two metres tall, is very hairy, and has beautiful deep blue flowers .
The roots produce a purple dye, but they do not yield anywhere near as much dye as the true alkanet. I am still waiting for my plant to spread, so that I can dig up some roots to try it out.