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…..

Dear Readers, I found a tree pit full of nasturtiums in Muswell Hill today, and it occurred to me that I know next to nothing about this popular plant, except that it is often used as a peppery addition to salads, and that it is a favourite food of greenfly. As usual, the common name causes some confusion: Nasturtium is actually the generic name for watercress, and I assume that ‘our’ nasturtium got the name because of those tasty leaves. The actual genus name for this plant, Tropaeolum, was given because it reminded Linnaeus of an ancient Roman custom, where the armour and weapons of defeated enemies would hung from a pole called a tropaeum. The leaves reminded Linnaeus of shields, and the flowers of bloody helmets.

‘Our’ nasturtium is actually a hybrid of three wild species, all of which come from South America. It grows here as an annual, and seems to prefer full sun and poor soil – in rich soil, it produces lots of leaves but few flowers. It is much more of a scrambler than a vine, though it can overwhelm smaller, more delicate plants. I rather like the tumble of leaves above, and the variety of colours.

As mentioned above, the leaves of nasturtium can be eaten raw, but the flowers are also edible, and often show up in the dishes of high-end restaurants. In fact, there is a whole section of delicious recipes on the BBC Good Food website here, including one for caramel sticky toffee cake. It seems to me that the nasturtium flowers are not integral to the bake, but then anything with the words ‘caramel’ and ‘toffee’ in the title must be worth a look, regardless.

I have mentioned that nasturtiums attract a lot of aphids, and one reason for planting this exotic-looking interloper is as a companion plant,  as the aphids attract ladybirds, lacewings and other predatory insects. Some gardeners also plant them as a ‘trap crop’ , in the belief that  cabbage white butterfly caterpillars prefer nasturtiums to the broccoli and cavolo nero that has been planted for human consumption. I would love to hear what experience you intrepid vegetable gardeners have had.

Medicinally, nasturtium has been used to make cough medicine, and it is also said to have some antibiotic properties. In Germany there is a herbal antibiotic made solely from nasturtium leaves and horseradish root, for use in sinusitis, bronchitis and urinary tract infections. In a study it was comparable with ‘normal’ antibiotics, but had fewer side-effects. We will certainly need new antibiotics as bacteria continue to increase in resistance to our existing drugs, so this sounds most promising. On the other hand, as the article has been translated from the German, I do wonder if the ‘nasturtium’ is actually watercress. Such are the confusions of common names.

Nasturtiums were also caught up in a scientific debate over a mystery that became known ‘Elizabeth Linnaus phenomenon’ in the eighteenth century. Elizabeth was the daughter of the famed taxonomist Linnaeus. One evening in the family garden in Uppsala, Sweden, she noticed that, at dusk, the flowers of yellow and orange nasturtium appeared to ‘flash’. Although she was only 19 and had no formal education,  she wrote a scientific paper about this strange sight, published in 1762. It was long believed that the ‘flashes’ were a result of some kind of electrical activity in the plant itself – it was a time when everyone was getting very excited about electricity, and were inclined to credit it for causing more or less everything.  The idea influenced the poetry of Wordsworth, among others: think of his famous poem ‘Daffodils’:

‘They flash upon that inward eye
Which is the bliss of solitude.’

Do daffodils ‘flash’? I’m not sure, and never have been, but the idea of flowers putting out little sparks of electricity was certainly on Wordsworth’s mind. And here is a quote from Coleridge’s poem ‘Lines Written at Shurton Bars’:

′Flashes the golden-coloured flower

 A fair electric flame′

However, in 1914 the idea was finally debunked by Professor F.A.W Thomas of Germany, who revealed that the effect was an optical illusion, caused by the eye’s reaction to the contrast of the orange/yellow flowers and the green leaves at dusk. What a shame. I rather like the idea of flowers producing their own lightning.

I am frequently surprised by the places that this blog takes me, and so it is again today. I found this picture of nasturtiums by the Romanian painter Octav Bancila, and immediately assumed that he was a painter of still-lives.

Bancila was, in fact, mostly a painter of people: the poor, the dispossessed, peasants and the Roma people, who were much despised (and still are today, and not just in Romania). Following the Romanian Peasants’ Revolt of 1907 he painted a series of pictures showing the conflict, including his most famous painting ‘1907’ showing a peasant running into gunfire.