Incidental greenery

As far as landscapes go, the city has an unusual terrain. On the horizontal, there are vast man-made plains - roads and pavements, car parks, and paved public spaces. Perpendicular, rising densely from the savannah, are great table-rock edifices - from town houses, to blocks of flats, to skyscrapers. With its human-scale infrastructure, the city is a great place to be for, well, a human. 

However, when you put yourself in the shoes of a plant, the chic modern city isn't the kind of place you'd naturally hang out. It's not just high levels of pollution and the likelihood of being trampled; the very fabric of the urban jungle - glass, concrete, tarmac, and metal - give cold, hard, and often non-porous surfaces which just aren't that friendly to vegetation unless it's in a designated planter.

And yet, when human activity ceases, it never takes long for a place to be reclaimed by nature. The fishing village of Houtouwan in China was abandoned in the 1990s and recently caught the tabloids' eye as a 'green wonderland swallowed up by mother nature.' Even in the abandoned village of Pripyat near Chernobyl, where there are dangerously high levels of radioactivity following the disaster in 1986, trees have sprung back and now out-compete the communist era tower blocks.

Those are two extreme examples, but most abandoned structures, and even places which are just a little less tidy, eventually become havens for wildlife on a macro scale, as the extended reprieve of a maintenance regime lets greenery proliferate. It's the most resilient of plants - the ones that are successful at eking out an existence with not much to go on but old crumbly mortar and a little moisture - that thrive on walls.

In fact, all around the city, older and crumblier walls are home to this modern kind of incidental greenery - and the more you look, the more you find. It comes in different guises, too. It could be a shaggy mane of moss on a graffitied wall, or it could sit perched like a garnish, surprising you with dainty flowers.

Buddleja is famous for its ability to grow on even the meagrest substrate. In the wrong place (and to the wrong person) it can be a real pain. But its masses of honey-scented purple flowers make it a magnet for butterflies and bees, and brighten the red brick city wall. Here it shares space with delicious creeping plant with succulent leaves and delicate purple flowers - even the plants cohabit in cities.

A brick wall makes a great climbing frame, when you're a plant. Brick seems to be the material of choice for leafy things - maybe it's because they have more plant-friendly nooks than bare slabs do, or a higher proportion of mortar to stonework, or both. I'm sure there's a study in this somewhere!

The city may be modern, but it isn't impervious to a plant with its roots in the Paleozoic era. Facing a glassy apartment block, an old stone bridge was covered with little ferns, lifting elegant fronds aloft in defiance.

These plants are both weeds and wonders. They're the perfect imposters - they were never meant to be there. But they are the bedrock of the plant life in the urban jungle, and should be cherished for supporting life in the face of adversity. Maybe, just maybe, once the dust has settled, long after civilisation has ceased, these plants will grow on and prosper...