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…..

Of all the things that grow in our cities, I have a soft spot for the ones that make their homes in walls. There’s something about these plants,  clinging onto life in such a dry, sun-baked, inhospitable situation that fills me with admiration. On Sunday, I found a whole wall full of Ivy-leaved Toadflax. Tiny plants were growing on the top and then seeding right down to the bottom, like a kind of botanical candle-wax. Once I got home, I started to do some research and discovered, to my delight, that the plant is designed to do just this: when in flower, the blooms turn towards the light, but once the flowers are over, it becomes ‘negatively phototropic’ – in other words, the seed heads bend away from the light, to deposit their seeds into darker places, like cracks or the shadow at the bottom of a wall. When I find out something like this, I want to rush out into the street, stand by a patch of Ivy-leaved Toadflax and tell everybody who passes about what a fascinating plant it is. Fortunately, my blog enables me to do this without being arrested.

Toadflaxes are a member of the Figwort family, which also includes such plants as Mullein, Foxglove and Antirrhinums. However, the trick to identifying a toadflax is to look at the lower ‘lip’ of the flower – this is called the Palate (because it guards the ‘throat’ of the flower), and is formed of two lobes.

Ivy-leaved Toadflax was brought to the UK from southern Europe in the early seventeenth century, and was said to have originated in the packing material of some statues that were imported from Italy to Oxford, hence its alternative name of ‘Oxford Weed’. It was a very popular addition to the walled gardens that were being built everywhere at this time but, in the way of things, it didn’t take long before it was advancing over the walls of inhabited places all over the country. Other vernacular names include ‘Mother of Thousands’ and ‘Travelling Sailor’, which attest to its colonising zeal. It covered the walls of Kenilworth Castle so vigorously that yet another name for it is ‘Kenilworth Ivy’. There is a lovely description of Ivy-leaved Toadflax in medieval times on the Highbury Wildlife Garden website:

“In Reading the Landscape of Europe, May Theilgaard Watts calls it Runes-de-Rome: “This plant is a part of every medieval city wall’ in France. “Clinging to the massive masonry that lifts Chateaudun above the Loire Valley, it undoubtedly felt the breath of molten lead poured on the enemy from the apertures above and received many a misdirected arrow from below.”

The plant seems to like the scabbiest, most broken-down walls, maybe because these contain the greatest variety of crevices and cracks. Richard Mabey notes that it is ‘virtually unknown in natural habitats in this country’.

In its native Italy, Ivy-leaved Toadflax is known as ‘the plant of the Madonna’. It is also said to be edible: it is described in old herbals as ‘anti-scorbutic’, which means that it is high in vitamin C, and has been eaten in salads. Its flavour is described as being similar to cress. I can imagine that those little flowers would look very pretty too, although taking them would mean depriving the bees of their nectar – like most plants with ‘snapdragon’-shaped flowers, it is insect-pollinated.

This leaves me with just one question. Why is a Toadflax called a Toadflax? The answer is lost in history, but one explanation is that the flower looks like the wide-mouthed face of a toad. Another is that the flower looks like a whole toad! There is also a theory that toads liked to shelter amongst the leaves, which, as they also like the crevices in drystone walls, seems to me the likeliest of the explanations. At any rate, having noticed Ivy-leaved Toadflax, I am now seeing it everywhere, and will certainly tell you if I spot any toads.