Wednesday Weed – New Weeds on the Block?

Greater Celandine (Chelidonium majus)

Dear Readers, there is a most interesting article in the London History Society Newsletter this month by Rodney Burton. He is looking at the common weeds in Hackney (just a few boroughs east of where I live) and is comparing the plants with the Flora of the London Area (1976) and Dougie Kent’s Historical Flora of Middlesex (1975). I have long suspected that the wild flora of the London area has changed dramatically during my lifetime, and this seems to be borne out by the historical record.

Greater celandine still doesn’t seem to be present in large numbers in Hackney, but wasn’t recorded at all in 1976. It was previously recorded in my part of London, and I suspect that it has become a little commoner if my back garden is anything to go by. However, a real surprise is Herb Robert, which was one of my very first Wednesday Weeds, and seems to me to be everywhere around here. In 1975, Herb Robert was said by Kent  to be ‘common except in heavily built-up areas where, owing to the absence of suitable habitats, it is very rare or extinct’. Well, it must certainly have adapted better to city life since then, because it seems to pop out of the tiniest crevices in pavement or at the base of walls. It is undoubtedly our most resilient and urban-tolerant geranium species.

Herb Robert (Geranium robertianum)

Now, the two species that look to have increased the most are two old favourites of mine. Firstly, Green Alkanet (Pentaglossis sempervirens). In 1975 this was so rare in North London that every single instance of its existence was recorded. Nowadays you are practically tripping over the stuff. Burton notes that, on the RHS website, it says that the plant is ‘spread by dogs’, though this may have now changed, because when I looked it merely mentioned that the seeds can become entangled in fur and transported in that way. However, an intriguing question raised by Burton is whether Green Alkanet is actually being spread by foxes: they certainly travel regularly through dark and weedy places, and several Green Alkanets have sprung up in my garden recently. If so, as Burton mentions, it might be that the spread of the plant has coincided with the increase in urban foxes. Stranger things have certainly happened. 

Green Alkanet

And finally, there is the rise and rise of Yellow Corydalis, one of my favourite ‘weeds’. Again, in 1975 every single individual record of this plant was mentioned. By 1998, Kent noted that the plant was ‘increasing’. Today, it pops up wherever there is a gap in a wall that doesn’t already have some ivy-leaved toadflax in it. Burton notes, as I have previously, that the plant’s seeds have an ‘oil body’ which makes them very attractive to ants, who will take them into their nests, where they will germinate and somehow find a root to the light. Does the ant link explain the spread of the plant, I wonder? Whatever the reason, it is such a delicate and airy plant that it seems to brighten up wherever it grows. It seems to me that if it was rarer, you could happily sell it in the garden centre.

Yellow Corydalis

So, we have ample evidence that within our lifetimes, our whole flora can change. I could add in a few more ‘weeds’ that I don’t remember from my youth, at least in such profusion: buddleia for one, but also the various bellflowers, Mexican fleabane and Canadian fleabane. Welsh poppy seems to be increasing in numbers during the past few years, and I am seeing a lot of hardier garden escapes, such as antirrhinums and opium poppies advancing up the streets of East Finchley. Climate change will no doubt bring its own winners and losers, and London is a hotbed for all kinds of exotic plants that escape from groceries, bought-in plants and industrial waste. As the cliché has it, ‘change is the only constant’. How useful citizen science is in these situations, and how much we owe to the people who monitored our flora and fauna in the first place!

Now, over to you. How has your flora changed during your lifetime? What’s new, and what’s lost? Do you have any theories about why some plants have thrived and some have been lost? I would love to know what’s happened in your neck of the woods. Weeds are by nature opportunistic, adaptable and resilient, so knowing what’s happening may give us some inkling about what’s going on.

Trailing bellflower, a great opportunist

And, because this post is for once a general celebration of ‘weeds’, those intrepid colonisers of our broken-down places, those joyful celebrants of life in the most unwelcoming and desiccated spots, here is an excerpt from ‘Inversnaid’, a poem by Gerard Manley Hopkins.

‘What would the world be, once bereft
Of wet and of wildness? Let them be left,
O let them be left, wildness and wet;
Long live the weeds and the wilderness yet.’

Amen to that, I say.

14 thoughts on “Wednesday Weed – New Weeds on the Block?

  1. Anne

    Oh what a joy this has been to read whilst sipping on my Lapsang Souchong tea first thing in the morning! You have attractive ‘weeds’ where you are; ours seldom sport pretty flowers. You have thrown out a challenge though – one I have been meaning to do something about – to find out more about our weeds. I have tended to focus individually on some of the alien invasive plants and should cast my net wider.

    1. Bug Woman

      Weeds are fascinating, Anne! They have a long relationship with humans, and I’m always interested to know how they’ve been used over the centuries, and how they arrived in the first place if they aren’t native. Let us all know what you find out!

  2. Janet Daniels

    Your picture of trailing bell flower looks more like wild violets , perhaps I’ve been calling it by the wrong name all these years !!!

    On Wed, 2 Sep 2020, 05:02 Bug Woman – Adventures in London, wrote:

    > Bug Woman posted: ” Dear Readers, there is a most interesting article in > the London History Society Newsletter this month by Rodney Burton. He is > looking at the common weeds in Hackney (just a few boroughs east of where I > live) and is comparing the plants with the Flora ” >

    1. Bug Woman

      Hi Janet, it’s maybe not the best picture, but the flowers are much bigger than those of a violet, are a pale lavender-blue and are bell-shaped. My next door neighbour actually does have dog violet growing in his path, though, so it’s clear that the plants like the same kind of habitat.

  3. Ann Bronkhorst

    Your fox theory to explain the spread of Green Alkanet appeals to me. Over the 54 years we’ve gardened here in E.F. I’ve noticed a rapid spread of the plant and yes, that coincides with the increase of urban foxes hereabouts. For me, the only virtue of this plant is its popularity with bees.

    1. Bug Woman

      Bees do love it, don’t they, but it’s a bit of a thug. Still, that intense blue flower always cheers me up, and the plant grows under my whitebeam where everything else struggles.

  4. FEARN

    I have the firm impression that Rosebay willowherb has taken over the UK in my lifetime. I don’t remember it in my childhood and now it is ubiquitous. I also associate it with the development of motorways (providing an unobstructed path, disturbed soil and also a vehicular slipstream to supplement natural wind transmission). Of course railways are equally sympathetic and they have been around longer than motorways. Isn’t this the fireweed noted as first to appear on bombsites? Now they seem to be set on world domination, well UK domination at any rate.

    The RHS lists nine nurseries that will supply you with yellow corydalis plants by mail order (One in France!). We have to go to a National Trust garden (Inveresk Lodge Gardens) to see it featured on a south facing stony bank. I have only seen red fumitory in the ‘wild’ to date.

    1. Bug Woman

      Yep, Rosebay Willowherb is indeed the ‘fireweed’ noted as taking over bombsites in the 1950s, and very pretty it is too, at least while it’s in flower. It is definitely one of those plants that spreads along in the slipstream of trains and cars, like buddleia and Oxford Ragwort.

      I also can’t believe that you can buy yellow corydalis, but it’s not ubiquitous everywhere I guess, and it is a great plant for walls. I love ‘proper’ ramping fumitory, which popped up in Dorset one time when I went to visit my parents. I actually picked some to show them because it was so pretty…

  5. Liz Norbury

    In May 1903, Ida May Rouncefield, who was then aged 13, entered a school competition to list the wildflowers to be found in her home town of Hayle, here in St Ives Bay. Ida managed to find 98 – an impressive total, but not quite enough for her to win first prize. Ida’s granddaughter – my friend Ann – thinks she came second or third! Ann would love to know how many of the 98 are still around, and next May, we plan to see how many we can find.

  6. Relly

    I live in Kent about 30 miles from London. I too have seen plenty of pretty Corydalis around (it looks great on church walls) and Green Alkanet is one of the most common wildflowers I see. For a longer-ago record of wild plants in London, you can look at Flora Londinensis (including the lovely illustrations!) on-line at:
    Written by William Curtis it was published in 1770, with the subtitile: Plates and Descriptions of such Plants as Grow Wild in the Environs of London.


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