Wildlife on Walls: 8. Ivy-leaved toadflax

Ivy-leaved toadflax Cymbalaria muralis, also known as Kenilworth ivy, is a well-established introduced species in our flora that's an attractive feature of walls all over Britain. It's been grown in gardens here at least since the beginning of the 17th. century and was first recorded as a garden escape in 1640, but I suspect that if it was a new arrival today the newspapers would be full of hysterical predictions about how this alien species would be about to disfigure our built environment and destroy our buildings. It comes from a restricted area of rocky subalpine habitat in southern Europe but, thanks to the construction of walls and migrations of people, has spread throughout much of the Continent. 

The delightful little snapdragon-like flowers bloom from early spring until late autumn and are visited by bees, but they self-pollinate and always set seeds prolifically.

Ivy-leaved toadflax tolerates the nutritionally challenging environment of wall crevices but if you grow it in soil with plenty of nutrients it will make rampant growth, as I discovered when I introduced it into my greenhouse, where I pull out handfuls of the plant from the gravel floor every summer.


Gilbert White, of Natural History of Selborne fame, also marvelled at the growth potential of this plant, which he knew as Antirrhinum cymbalaria, and commented on it at least twice in his journals.


Delighted by the plant, on April 30. 1780 he wrote: ‘A sprig of Antirrhinum cymbalaria, the ivy-leaved Toadflax, which was planted last year on a shady water-table of the wall of my house, grew at a vast rate, and extended itself a full nine feet; and it was in perpetual bloom ’til the hard frost came.  In the severity of the winter it seemed to die: but it now revives again with vigor, and shows the rudiments of flowers.  When in perfection it is a lovely plant. ‘


Then, five months later on 16th. September, came this excited journal entry: 'The Antirrhinum cymbalaria is grown to an enormous size, extending itself sideways 15 or 16 feet, and 7 or 8 in height!!'


You can read the rest of his fascinating journals at this simply brilliant web site..

Aside from its prolific seed set and potential for rampant growth, the other ace card that ivy-leaved toadflax holds is a mechanism for sowing its own seeds in the dark, damp crevices of walls. During flowering its blooms face the sun but as soon as seeds are set and the flower pedicel begins to  elongate the seed capsule becomes negatively phototropic, growing away from the light and towards the nearest dark crevice before the capsule bursts open. The seed capsules in the photo above are just beginning their search for somewhere shady to shed their seeds.

Wall plants

Inland cliffs are a relatively rare habitat in many parts of Britain but man-made walls are equally acceptable for most cliff-dwelling plants. These two species – ivy-leaved toadflax (aka Kenilworth ivy) and yellow corydalis - are currently in flower on walls around Corbridge in Northumberland. Neither are native – both come from continental Europe – but they’re a welcome addition to our wall flora and put on a good display from spring onwards. Both thrive on walls here and ivy-leaved toadflax has a neat trick of developing fruit stalks with an aversion to light, so that they grow into dark wall crevices and deposit their seed there. The corydalis seed capsules simply burst to scatter their seed, but first the flowers need to be pollinated and today this mining bee seems to have been performing that role – does anyone know what species of bee it is?

Summer in the City

We did a bit of botanising more or less in the centre of Newcastle today. Tucked away in little pockets of waste ground there are all sorts of rural wild flowers growing in unlikely urban habitats. Are they accidental arrivals, originating from seeds brought in by birds, traffic and people, or are they remnants of a past flora that existed when this sprawling city was still green fields? A bit of both, I would guess. The lady’s bedstraw (top photo), flowering in the shelter of a billboard on the road to Byker, belongs in a hay meadow rather than in a tangle of overgrown shrubs and litter. The tansy (second photo), with yellow button flowers and aromatic foliage, was flourishing in a gap between a wall and a tarmac-covered car park, a long way from the hedgerows and riverbanks that are more familiar natural habitats. Yellow toadflax (third photo), established in the crevice between a factory wall and the pavement is a refugee from grassy places and hedgebanks, but seems to be thriving in the urban jungle. Rose-bay willow herb (fourth photo from top) colonises waste ground everywhere via its wind-blown seeds but how does wild parsnip, in the foreground of this photograph, get around the city and appear as a regular coloniser of disturbed soils? Wherever it grows, its flowering shoots become infested with aphids, attracting ladybirds (bottom picture). It’s tough on the city streets, but nature is tougher..........

Plants on walls

 Chasmophytes are specialised plants that colonise crevices in bare rock faces - ivy-leaved toadflax is a notable example, that even produces seed capsules that grow towards dark cavities, planting their own seeds back into the wall. But there are a surprising number of plants that colonise the man-made equivalent of rocky cliff faces - either drystone walls or walls constructed with mortar. 

Here are a few of the accidental wall colonists that I've encountered recently.

Native wild strawberry on a wall top at Stanhope in Weardale, undoubtedly arriving as a seed in a bird dropping

Native dog violet in a damp retaining wall beside the railway line at Hexham in Northumberland. It has a ballistic seed dispersal method, firing out seeds when its capsule splits and contracts

Native shining crane'sbill in a drystone wall at West Blackdene in Weardale. This plant, a wall specialist, has leaves that turn bright crimson as summer progresses, perhaps induced by stress as conditions become drier.

Non-native trailing bellflower, on a wall top beside Quarry Heads Lane in Durham city. Escaped from a nearby garden.

Native wall lettuce, another wall specialist with plumed seeds that are carried on the wind. Growing here on a ledge below the parapet of Prebends bridge, spanning the river Wear in Durham city.

Moth mullein, a non-native, well established in the wild. Here, on old walls beside Sunderland Marina. 

Wallflower, doing exactly what its name dictates, growing in a wall beside Sunderland Marina. Cultivated since medieval times but well established on walls in the wild.

Summer in the City: Where the Wild Things Are....

Botanically, there are two sides to a city. There's the carefully manicured, redeveloped part that has been purged of any plants that are out of place - and that doesn't get much more sterile than the one above, which is Northumbria University's campus. The only living greenery in this canyon of glass, stainless steel and concrete is the row of lollipop hornbeam trees on the right, with their foliage clipped into a neat cube. The green circles are astroturf (although I did notice that a plucky real fern was just beginning to grow around the edge of one - it won't last long).

For the other botanical face of a city, you need to venture just a few streets away from the centre, where the wild things are.

There you'll find the Buddleia davidii in full flower in late July, adding beauty to old walls.

The flower heads are magnificent this year, perhaps because the shortage of water that usually kicks in in late spring in cities just didn't materialise. All that rain kept the wild flowers growing and flowering ....

 ......but there are no butterflies to enjoy the Buddleia flowers yet.

This is lady's bedstraw, blooming alongside ripening brambles in one  of the less manicured parts of Newcastle. Who knows how this plant, that's usually associated with dry haymeadows, came to be here. Brought in with fodder with horses maybe, before the age of the automobile, and hanging on ever since? Maybe a relict of the distant days when all this was open fields? We'll never know, but it's a welcome reminder of the countryside in the heart of a city.

Pure white trumpets of bindweed clambering through an old, broken down fence. Its brittle underground rhizomes are moved from place to place when soil and rubble is shifted.

Drifts of hawkweed, rose bay willowherb and wild parsnip in an old flower bed that's no longer maintained - maybe one of the less unpleasant consequences of public spending cuts?

Scentless mayweed, a cornfield weed, growing alongside a security fence around a construction site.

Drifts of melilot, growing on a rubble-strewn ex-industrial site. The plant has a powerful aroma of new-mown hay and you can smell it from some distance on a warm day.

A double-flowered opium poppy, a refugee from a long-vanished garden, growing on rubble.

By next year this bank of rubble will be bulldozed away, when this site is redeveloped, but for now it's home to corn poppies, oriental poppies and dyer's rocket .... and a host of other wild plants.

A lot of wild oats are sown in the centre of Newcastle on Friday nights, these were thriving in a neglected flower bed.

Rose bay willow herb on the edge of the Shieldfield industrial estate, five minutes walk from the university campus in the picture at the top of this post.

Ragwort amongst the broken bricks.

Tansy, which has a powerful aroma when it's crushed......

....... with tall stems threaded through a wire fence.

Yellow toadflax growing between a link fence and the pavement.

Wild parsnip puts down roots wherever derelict land provides a temporary opportunity ....

.... to display its tall flower stems .....

... that brighten up even the most brutal urban architecture.