In the first session we turned our attention to moss. Using Robin Wall Kimmerer’s ‘Gathering Moss: A Natural and Cultural History of Mosses’ as a field guide. Kimmerer is interesting not just for her knowledge of moss, but also for the way she thinks about the relationships between humans and plants. While recognising that this often is a destructive interaction she also draws attention to other nuances of this relationship. For example in the chapter ‘City Mosses’ she writes about how self-seeding city plants might have been with us as a species from the start:
We tend to devalue the flora of cities as a depauperate collection of stragglers, arising de novo with the relatively recent development of cities. In fact, the urban cliff hypothesis […] suggests that the association between humans and these species may be ancient, dating from our pre-Neanderthal days when we both took refuge in cave and cliff dwellings. In creating cities, we have incorporated design elements of the cliff habitat and our companions have followed. (pgs 97-98)
It is interesting to rethink urban plants as companion species. This seems to open up a different way of caring for our landscapes and not writing off developed spaces as degraded areas. In mapping the sites for our workshops we found some of these urban cliff parallels, finding similar plants in craggy coastal rocks as were growing through the cracks in the walls of pedestrian subways. The same plants were taking root and even thriving in these vertical resting spots.
Moss is a particularly successful and versatile companion species. It finds its way into most urban spaces (although it disappears when pollution levels are too high). Kimmerer writes about how the simplicity and smallness of moss is behind it’s success as a plant. Mosses make use of a micro-environment known as the ‘boundary layer’.
The sun’s warmth gets trapped in the tiny layer of still air. Since the air is nearly motionless, it acts as an insulating layer, much like the dead space in a storm window, which forms a barrier to heat exchange. The spring breeze around me is chilly, but the air right at the surface of the rock is much warmer. Even in a day when the temperature is below freezing, the mosses on a sunlit rock may be bathed in liquid water. By being small, mosses can live in that boundary layer, like a floating greenhouse hovering just above the rock surface. (pg. 18)
The scale of moss is what helps it to take root even in places where there is little to hold onto. Unplanned nature in cities is usually small in scale. Instead of vast panoramas we are peering into cracks, and finding overlooked corridors and pathways. Moss is a plant of surfaces, and it adorns the structures which are already in place. It can turn cracks in a building into something beautiful. This beauty has something to do with hope. That in an expense of concrete at the slightest crack of opportunity something green will take hold.
The limiting conditions of a city allow us to appreciate these pioneering small plants. It is almost a recreation of the evolutionary story. The simplest plants taking hold first and creating a foundation for more to follow. Mosses are a significant plant in the evolutionary chain. They were the bridge from aquatic to land plants. (In fact they are still between the two, relying on water to allow germination between individual plants). By being able to survive out of the water they created a foothold on land which allowed for other plants to follow. It continues to carry out this foundational role in challenging and degraded landscapes.
In the chapter/ essay ‘Binding up the wounds: Mosses in Ecological Succession’ Kimmerer describes a deeply damaged landscape near her home. Mining has turned the area into a kind of desert and plant life is struggling to take hold decades after the mine has been abandoned. However some plants have taken root, and she finds that where the moss has arrived, other plants have followed. The aspens:
‘had somehow gotten started in this desolate place that everyone wanted to cover in garbage. We know now that these aspens originated from seeds caught on a patch of moss, and the whole island of shade began to grow from there. The trees brought birds and the birds brought berries – raspberries, strawberries, blueberries – which now blossom around us. The centre of the grove was cool and shady and the leaf litter from the aspens had started to build up a thin layer of soil over the tailings. Sheltered from the harsh conditions of the mine, a few maple seedlings, migrants from the surrounding forest, were holding their own. Brushing aside the leaf litter, we uncovered the remnants of polytrichum, the first plants to begin healing the land, making it possible for others to follow.’