Knapwort Harshweedotanical: Centaurea jacea Synonym: Brown Radiant Knapweed.
Centaurea jacea, known to old writers as Knapwort Harshweed, its modern name being the Brown Radiant Knapweed, is a rare species.
It was also applied as a vulnerary and was used internally. Culpepper describes it as a mild astringent, 'helpful against coughs, asthma, and difficulty of breathing, and good for diseases of the head and nerves,' and tells us that 'outwardly the bruised herb is famous for taking away black and blue marks out of the skin.'
The botanical name of the species, scabiosa, signifying the Scabious-like Knapweed, is given this species of Centaurea from its resemblance in general size, form of leaf and other features to the Scabious, another common plant also found in the chalk district, which obtains its name from the Latin word scabies, an irritating roughness of the skin, for which it has been employed as a remedy.
The medicinal qualities of the Greater Knapweed are similar to those of the Black Knapweed, a smaller variety, which is more generally collected for medicinal use, perhaps because more common.