TALK TO YOUR PLANTS

Xanthe White sees the well-travelled Boston ivy (who is not from Boston, thank you very much!) in a new light.

Q I have to be upfront with you and say I am always nervous of exotic climbers, given the delicate state of our native flora. At the same time, I confess that I am fascinated by ruin-ism and how nature can so quickly reclaim what we view as solid and certain. A plant that can transform a concrete block into a living world has to be admired. Your success as an urban plant led me to wonder where you came from to be so capable of such feats… a stony outcrop perhaps?

A Not at all, and nor are we from Boston as is so often claimed.

In the wild, we are found in subtropical zones in Asia with climates similar to parts of New Zealand, such as Japan, Korea and some regions of China. Generally, we like areas of high rainfall and riparian zones.

Riparian – as the area beside the water – is a very important and diverse part of any ecology. Competition is, of course, very high in these zones and there are a lot of different niches in which you can establish yourself. Areas prone to frequent flooding can be unstable with a lot of earth movement and the force of water pulling at you constantly. But here also, as well as the water, the soil is very fertile and rich with minerals and silts bought down frequently from inland forests. So the ability to cling on to a riverbank or a tree protected us from being pulled from the earth in large floods. It helps us make the most of this sweet zone.

Q

That makes so much sense. So what’s the trick? How do you manage to cling to wood or concrete? Do your roots break into the surface like an epiphyte?

A Again, no not at all! The way we attach is by using calcium carbonate on the surface of the material we are attaching to. There is no damage at all to the structure. It is probably best described to you as making a small bed of mortar at multiple points where our roots attach or gluing ourselves to the surface. There is little damage at all to a building of stone or concrete.

Wood, of course, is different. Wood is usually painted and that paint work could be peeled back if you pull us roughly from the surface. If we are first cut back, we will gently release as we die – with less damage.

And whether the building is wood or stone, if there are cracks and crevices, we will attempt to enter, winding our way beneath a windowsill towards the warmth within or under the tin of the roof.

Q

It’s amazing that a plant that has the energy to climb 30m high over a building can afford to drop its leaves.

A Dropping leaves is not a relinquishing of energy. It is simply a shifting of stores of carbon from the stems to the roots. In winter when it’s cold, the tissue of leaves, being full of water, are easily damaged by frosts or snows. The water simply freezes. But the dropped leaves create a warm pocket above the earth even in snowy conditions that keep the roots warm, and they, in time, create soil and add to the rich reserves of a swampy forest or river bank.

Q Nature’s mulch.

A Yes, and you could say the same for our ability to reclaim the concrete jungle, for the wellbeing of all. The temperatures in urban environments are hostile to the elderly and young children during hot periods, and this issue is increasing as cities grow higher and temperatures overall rise. Many cities such as Paris and London won’t let new buildings be built if they do not have green space either on their walls or roofs. While it’s true that without human interaction, given the chance, we would not differentiate from a road or footpath or a wall where we might be wanted, but gardening is about relationships. You may not want us in your forests, but in cities around the world, plants like us are needed to transform these somewhat harsh environments into more liveable places. Q Concrete versus the vine. A Indeed.