Canadian Fleabane (Conyza canadensis)

Dear Readers, the fleabane by the side of my water butt is finally in flower, and I’m happy to report that it is, indeed, a Canadian Fleabane. But how can you tell, when  there are various other Fleabane species about? First up, each flower is topped with a little white ‘crown’, and the green ‘bit’ that the flower emerges from, the bract, is pretty much hairless.

Then we have Bilbao’s Fleabane (Conyza floribunda) which is a more recent introduction first seen in 1992 (Canadian Fleabane first put in an appearance in 1690), and can also be found in London and along the south coast of the UK. The flowers are very different, as you can see – the flowers look ‘pinched’ at the top, as opposed to cylindrical, and often have a red tinge.

Bilbao’s Fleabane (Conyza floribunda) (Photo By Meteorquake – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=143713818)

And then  there’s another ‘recent’ introduction, Guernsey Fleabane (Conyza sumatrensis), which first appeared in 1974. This has flowers of a similar shape to Guernsey Fleabane, but the bracts are very hairy, and the flowers are often tipped with purple.

Guernsey Fleabane (Conyza sumatrensis) Photo By Meteorquake – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=143648891

So, Canadian Fleabane  originally came from North America, while Bilbao’s and Guernsey Fleabane originated in South America. All three species have been extremely successful – they have tiny, light seeds that are easily distributed in a gust of wind and, as my garden suggests, this genus can establish itself wherever there’s a suitable crack in the pavement. In fact, in their book ‘Alien Plants’, Clive Stace and Michael Crawley have identified that there can be ‘waves’ of different Fleabanes, with Canadian Fleabane being replaced by Guernsey Fleabane  and then by Bilbao’s Fleabane. The authors point out that it’s not currently known exactly how this works, but for me it’s interesting – all of these species need open ground and sunlight in order to grow (so are all eventually outcompeted by slower growing, more heavily-leaved plants), but whilst Canadian Fleabane started off as a plant of wasteland, it’s now more often found on cultivated and fallow arable land. Guernsey Fleabane has taken a shine to railway ballast, and Bilbao’s Fleabane is found on brick paths. There is so much about ‘weeds’ that we don’t understand, and which can teach us all kinds of things about why some plants survive, some don’t, and how the relationships in a natural community change over time.

And now, let’s have a look at what we’ve found out about Canadian Fleabane and its relatives previously…

Fleabane (probably Canadian) with ragwort at Woolwich Dockyard

Dear Readers, Canadian Fleabane (and its close relatives Bilbao’s Fleabane and Guernsey Fleabane) are such weedy weeds that it’s easy to pass them by without so much as a second glance. Members of the Asteraceae (Daisy) family, they have tiny flowers and a whole lot of fluffy seeds and are annuals of such fecundity that once you have the plant on a patch of rough ground or, as here, along a riverside, you are probably going to have it forever. Experiments outlined in my book ‘Alien Plants’ by Clive Stace and Michael J. Crawley suggest that grazing with rabbits seems to be a way to keep the Fleabane (Conyza) genus in check, but there’s a grave lack of small furry grazing animals in Woolwich, clearly.

Fleabanes tend to grow alongside buddleia, as I noticed from the Woolwich walk.

Buddleia!

The name given to the community of plants established by buddleia and fleabane is the Buddleia-Conyza scrub community, and you can see it popping up in many urban sunny sites, frequently on builder’s rubble or tarmac – we have a great example of this just up the road from here in East Finchley on the site of an old petrol station which has been landbanked by developers for years, but you can also find great examples on railway embankments. Fleabanes tend to be the first colonisers, along with mugwort, American willowherb, bristly oxtongue and evening primrose, but soon the buddleia and the sycamore start to take over, with the fleabane tending to die out where it’s overshadowed by the buddleia. This feels like such a very urban habitat that I’m glad that it has its own name and now has people studying it. Colonisation can start within a year of a site being left derelict, and the habitat can persist for up to twenty years. It will be interesting to see how long the example of the Buddleia-Conyza complex in East Finchley lasts before someone decides to actually build there.

And when I looked back at the last time that I wrote about Canadian Fleabane, I mentioned that there was a patch at the side of my house. When I looked early this week, there was still some there, probably descended from the seeds that were dropped by the parent plant back in 2014. You have to admire the plant’s sheer persistence.

So, this is from my original post back in 2014.

A thicket of Canadian Fleabane has erupted in the alley at the side of our house, and I am delighted. I know this is not the reaction that most people would have, but then, this week is the thirteenth anniversary of my marriage to my Torontonian husband, so a little reminder of the country that he came from is very welcome. Plus, although this plant comes from so far away, it has put down firm roots in London, and is more commonly seen in the Capital than in any other city, so in that respect it is a little like me.

There are lots of plants that resemble Canadian Fleabane, but none have such a mass of tiny flowers, which at this time of year are rapidly turning into fluffy seeds. The plant was apparently brought to the UK as seeds in the innards of a stuffed bird, back in the sixteenth century (unlike my husband who arrived into Heathrow in a big metal bird twenty-odd years ago).

In many ways, Canadian Fleabane is a ‘proper’ weed – it’s an annual which produces thousands of seeds, and which can grow in the most unpromising of spots, as its appearance in my dark, soil-less side alley proves. But, as with so many plants, it has a myriad of helpful uses. A tea made from the plant is said to be helpful for arthritis and for diarrhoea, and it has also been used to combat hay-fever. Like so many fleabanes, it is also said to be good for deterring insect parasites.

Some wind-blown Canadian Fleabane

I can’t help but admire a plant that can erupt from a crack a hairs-width wide and grow to four feet high in a single season.  This afternoon, the little seeds were flying away in the breezy weather, taking their chances on a new land far from where they started. And, thinking of my soulmate who flourished so far from his native soil, I find myself wishing them luck.