Wednesday Weed – Ageratum

Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Ageratum conyzoides

Dear Readers, as I looked out of the window of the coach as we travelled through Costa Rica, I noticed that some of the fields had a gentle lilac haze, as if fairy smoke were wafting upwards.

‘Blimey’, I thought to myself, ‘those plants look for all the world like the Ageratum that’s in municipal flower beds all over London’.

And indeed it is. Later in the holiday I went for a walk on my own, fell down a hole, got bitten by an ant and then discovered a tiny plot of this plant, growing where a tree had fallen over and the sun could penetrate. It is not a fussy plant, apart from requiring a little sunlight, and in Vietnam it is known as ‘pig shit’ because it often grows around pig sties. It’s also known as Billy Goat Weed. This is a plant that leads many lives: as a native beauty in Costa Rica and other parts of Central America, as a domesticated space-filler in the UK, and as an invasive weed in Africa, Asia, and North America.

I love that a plant that usually hangs out with alyssum and blue lobelia in front of a statue of some Great Colonial Gentleman is actually native to Costa Rica, where it’s known as Santa Lucia, and is believed to bring great good fortune. As the Tico Times explains, if someone gives you a bouquet of the plant at New Year, and you put some of it in your wallet, you will never be short of cash. The name Ageratum means ‘non-ageing’, which refers to the long-life and prolific flowering of the plant.

There are lots of species of Ageratum, and lots of cultivars too – the popular one around these parts is ‘Blue Mink’. It is an inoffensive and hard-working annual, and I love the softness of the colour, especially when compared with the brasher bedding plants that are available. Ageratum is a member of our old friends the Asteraceae, or daisies, and so the flower is actually a conglomeration of lots of smaller ‘florets’ – disk florets in the velvety centre of the plant, and ray florets forming the ‘flower’.

Fluffy Ageratum flowers (public domain)


Fluffy as it looks, though, Ageratum is not without its problems. It can cause liver lesions and tumours, and there was a mass poisoning incident in Ethiopia in 2005. 118 people were affected, with a 38% fatality rate. It was eventually found to be due to some Ageratum growing in the village well – the plant was used to dry the cooking implements that the women washed there, and it was also used to cover the pans to protect the contents from flies. Interestingly, despite its toxicity the plant is used medicinally to treat dysentery, malaria and many other tropical diseases across both its native and its introduced range, but it is more commonly turned into an insecticide. It can also be used to treat worms, but I suspect that in this case the cure is much worse than the disease. All this makes me think that people who get to know the plant are able to prepare it in ways that reduce its toxicity.I note that there are some sites which seem to think that the flowers are edible, but I will stick to violets, thank you very much.

Photo One by

Ageratum in bud (Photo One)

While I was looking for images for this piece, I found the vintage seed packet below (go to the link under the photo credit if you collect such things). It made me sigh a little with nostalgia, for I remember when seed packets had paintings of the plants that were expected to burst forth from the seeds, rather than photographs. As I am considering my seeds for this year, it also reminded me that the saying ‘every seed a plant’ is a little optimistic, at least when it’s me that’s doing the planting. Either nothing comes up, or everything does, and then I have the job of thinning out which goes against the grain, because don’t they all deserve to live? I sometimes think that I don’t have the iron spine required of a gardener, what with my toleration of slugs and my lack of ruthlessness.

Photo Two from

Vintage Seed Packet (Photo Two)

And for this week’s poem, how about this one by William F Dougherty, an American poet and someone that I hadn’t come across before. This one takes a couple of readings, but I love the image of the broken vase, and it reminds me very much of my visits to the cemetery.

A Promise to Keep by William F Dougherty

I promised her the garden’s glory:
marigold’s monarchal blooms,
ageratum’s lavender fuzz, the
grainy beards of coxcombs’ plumes;
sturdy zinnias, salvia’s flames,
snapdragons, and tiger lilies: raw
cuttings from home to grace a stone
in final, promissory awe.

Crystal-needled frost struck and drained
the promised flowers brown; left them
in rows of shriveled heads to nod
on gallows of each blackened stem.
I bought chrysanthemums and filled
her navy vase with bronze and gold
clusters to decorate the grave—
my quaking hand let slip its hold.

The vase discharged against a stone
and shattered, as if the cobalt night
had cracked again: the fragments gemmed
my gold bouquet with bluish light.
The flowers lost—love left unsaid—
planted in my repentant sleep
the seeds to start a garden of words
where love and promises will keep.

Photo Credits

Photo One by Carol Krol at

Photo Two from

William F Dougherty’s poem, and others by him, can be found here





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