I have recently noticed Canadian fleabane growing in The Byes. It must be a good year for it, as now I recognise the flower. I see it growing everywhere, in cracks in the pavements, at the edges of carparks. In Sidmouth, Mill Lane and Manor Road have plenty.

The plant has been in Britain for a long time. Some books say it came in cargoes from Canada to London docks in the nineteenth century and spread along railway lines. Other books say it has been here for 300 years. As West Country ports have been trading with Canada since Cabot sailed from Bristol to Newfoundland in 1497, there have been many opportunities for its introduction.

Canadian fleabane flowers from August but this year it has reached its peak in October. It is an annual with spires of flowers from one foot to three feet high. On close examination the flowers are pale green and yellow with white seed parachutes, but the general look is of a grey flower spike.

It was used by indigenous peoples to make smoke in sweat lodges, as a medicine for dysentery and was burnt to ward off insects.

Our native common fleabane is quite a different plant. Up to three feet high, it flowers from August to September and has small yellow daisy like flowers. Culpepper in the seventeenth century says that the smell of the fresh plant attracts fleas, but that its juice kills them so that laid on the floor the fleas flock to it “and never leave till the season of their deaths”.

Blue fleabane is another native plant. It grows about three feet high and despite the name the flowers are pink but appear blue from a distance. It grows mostly on dunes and dry coastal places.

Mexican fleabane is a non-native that has come from America. It has escaped gardens and is now widespread on walls and pavements.

So, the next time you are walking with your bubble and you see a tall grey flower spike growing from a crack in the pavement, say “Ahhh, Canadian fleabane” Then you can bask in the bemused silence you have provoked.