Greater Knapweed an ancient wound herb
Greater Knapweed, Centaurea scabiosa, is much prettier than its latin name suggests. In fact, photographer Steve Chilton seems to find it completely addictive as a photography subject. There’s a lovely picture of it on his Flickr page, here. Other names by which this plant has been known are scabious knapweed and greater centaury – though it is not related to the centaury, and does not resemble it at all.
Unfortunately, due to the rules of nomenclature, scabiosa is its species name, and it’s stuck with it. The name was given because of some putative resemblance to another plant, the devil’s bit scabious (so-called because the roots are truncated, as if bitten off, presumably because the devil’s realm was believed to be underground), but really this is extremely superficial, as the shape of the flowers is entirely different. In old materia medica the plant is also sometimes called by the latin names Centaurium majus and Rhaponticum vulgare.
Greater knapweed is very attractive to butterflies and is the only known food plant of the moth Coleophora didymella, according to Wikipedia, but I haven’t been able to find a common name for this moth, and what it looks like I have no idea.
Greater knapweed is a hardy perennial which reaches a height of around 3 feet (90cm). It is native to the UK and Europe, reaching as far as Western Asia and the Caucasus. It’s also naturalized in much of the United States where it may be regarded as a weed (which, as a wild plant, is a fair description, despite its attractive flowers).
Greater knapweed is closely related to the black knapweed, mountain cornflower and common cornflower.
Greater Knapweed will grow in any well drained soil, even nutritionally poor and very alkaline soil, and will withstand drought. It will not grow in shade.
Other members of this family are known to be unsuitable for use by pregnant women, so it is probably best to be prudent and use some other remedy in this case.
Medicinally, the roots and seeds are used. Greater knapweed is not often found in modern herbalism, even though it was highly regarded in the Middle Ages as a treatment for wounds and skin infections, and recommended by the Duke of Portland in the Universal Magazine as a treatment for gout. It can also be used as a tonic, a diuretic and to induce sweating.
For all these uses, make a decoction using 1 ounce (30g) of dried chopped roots or seeds to 2.5 US cups (570ml, 1 UK pint) of cold water. Put in a small non-aluminium saucepan and bring to a boil, then simmer until the liquid is reduced by half and strain before use. The dose is up to 1 US cup (240ml, 8 fl oz) a day, split into 3 equal doses).
It’s important whenever you are growing plants for use in herbal remedies that you stick to organic growing methods and pest control, to avoid the active constituents being masked or even entirely eliminated by foreign chemicals. To find out more about growing organic herbs visit the Gardenzone.
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July 26th, 2010 at 19:46
What do I do when I get spotted knapweed on my leg? It itches.
July 26th, 2010 at 20:28
It sounds as if you have an allergy to greater knapweed – which means you should avoid using it in medicine, and also its close relatives, such as cornflower (which is used for soothing itchy skin, but not in this case). Other herbs which are useful for relieving itching are alkanet, musk mallow and peppermint. You could also try the good old dock, which is pretty good in many cases.