Ageratum

Coming back from the garden club meeting yesterday at Willow Vale we noticed several fields covered in a blue flowering weed.This is also common on our property and is called Blue Billygoat weed. Although we do not eat it, when we attended an edible weeds talk at the Nambour Garden Expo a few months back the presenter did indeed mention that she considered it edible.

Binominal name : Ageratum conyzoides
Common name : Blue Billygoat weed

Identification :

This plant comes from Mexico/Central America and there is several cultivated varieties as a bedding flowering plant. It is a herb to about 1 m with blue/mauve flowers. Leaves are ovate or triangular and are about 5x7cm in size. When the leaves are crushed they emit an aromatic mint scent ( this chemical has been identified as eugenol)


Traditional use :

Cribb in Wild Medicine in Australia records that it is used for "cuts, sores and fever" in Malaysia and Indonesia (ref 1). It has also been used as a tea for colds and flu in China.
Traditional use also includes diabetes and indeed a rat model of diabetes does show reduction in blood glucose levels (ref 2)

Pubmed search (Search term: Ageratum) :

abstract 1: essential oils from Ageratum had some antibacterial effect but NOT against 2 common human pathogens ( E Coli and Staph)
abstract 4: Forty cows died after grazing on Ageratum in Mexico . At autopsy, haemorrhages were found in joints, muscles and internal organs ( heart,liver and kidneys). Chromatography revealed coumarins,alkaloids and triterpenes. The coumarins are what would have caused the internal bleeding ( coumarin = warfarin which is what is used in humans to prevent clotting and it needs to be carefully monitored).
abstract 7: This study reported finding 4 pyrrolizidine alkaloids in Ageratum. These are not good to be eating as they cause liver damage and cancer long term.

Apparently this plant deters insect attack by way of a chemical that interferes with metamorphosis. It certainly seems to be left alone by insects on my property.


Conclusion: Although some may consider this an edible plant I do not, until there is much better evidence to the contrary. Indeed, having pyrrolizidine alkaloids and coumarins makes me even more wary.

Tom

ref1:Cribb Ab and JW : Wild Medicine in Australia : 1981 Fontana/Collins pg158
ref2: http://www.bioline.org.br/pdf?tc06039


Still busy preparing for a medical conference presentation soon