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…..

Smooth Sow Thistle (Sonchus oleraceus)

Dear Reader, so far in this series we have looked at plants which are elegant (the Pendulous Sedge) or delicately pretty (Herb Robert and Herb Bennet). Today, however, we are looking at a real bruiser of a plant, the Smooth Sow-thistle. It can be distinguished from its close relative, the Rough or Prickly Sow-thistle, by its less spikey leaves, and because the way that the leaves join the stem is slightly different (for an excellent illustration of this, look here.)

The appearance of Smooth Sow-thistle is not helped by the way that no sooner has it forced its way through the concrete than it seems to be immediately set upon by all manner of other organisms. Its lower leaves are often furry with mildew, and, if you look closely, you will see that burrowing insects have taken a fancy to it too – there are  pathways where a miniscule grub has munched a path within the leaf itself.

Here you can see how something has been making a pathway inside the leaf…

There is one species of leaf-mining fly, called Liriomyza sonchi, that is so fond of Sow Thistles that there was some thought of using them as a biological control for the plant in Canada. This is the likely culprit for the white squiggles in the leaf photo above. Tiny grubs, small enough to fit between the layers of the leaf, have chomped tunnels and hallways until they have more or less hollowed it out. Then, they exit the leaf, pupate and hatch into a new fly, to start the cycle all over again.

The name ‘Sow Thistle’ is said to come from the way that female pigs would seek it out after giving birth. The plant’s milky sap was seen by herbalists as an indication that it would help nursing mothers, both human and animal, to increase the amount of milk that they produced. It has an alternative name of ‘Hare’s Thistle’, and it is said that there is no plant that rabbits and hares would rather eat. The lovely website A Modern Herbal   describes how ‘ ‘when fainting with the heat she (the hare) recruits her strength with this herb: or if a hare eat of this herb in the summer when he is mad, he shall become whole.’

Although Smooth Sow-Thistle looks like the quintessential garden weed, it has a long and illustrious history as a food plant. Pliny writes that, before he tackled the Minotaur, Theseus was feasted ‘upon a dish of sow-thistles’. In her book ‘Wild Flowers’, Sarah Raven describes how Rose Gray of the River Cafe would harvest the leaves of the closely related Prickly Sow-thistle for salad in March and April. It seems that it’s not just the leaf-miner who has a taste for juicy young leaves!

The Smooth Sow-thistle is one of those plants that is everywhere, but which is generally unregarded and unloved. It sits up against a wall, munched-upon and covered in fungus, and yet it is described as being useful for all kinds of inflammation, rashes, sores and ulcers (as a poultice) and as a cure for diarrhoea (when taken as an infusion, but note that it acts as a purgative).  What I am discovering is that, even here in London, I am surrounded by plants which have had a long relationship with us, and are now sadly neglected, or regarded as a nuisance. With every new plant I identify, I am finding a new sense of connection, of being (dare I say it) rooted in the place where I now live.

A Smooth Sow-thistle under attack

I’d also like to let you know about this wonderful website that was recommended to me last week. For anyone interested in Britain’s  flora, this is an invaluable resource…

Seasonal Wildflowers