This is interesting that you are referring to green walls as a typology of biomimicry. I had not thought of vertical gardens, green roofs, or other applications of green walls as a form of biomimicry because they are already a natural source imbedded into architecture rather than a imitation of nature or other living species. But as a result of reading this blog (Green Walls), what came to mind was the idea of time and how the buildings, in some sort of way, are growing. The green walls are adding a living element onto the facade of a building for beautification, increase in air quality, and other benefits. One way green walls can be a symbolism for the growth of natural is the way the plants change over seasons and grow over time.
The above image shows a series of photographs taken over the year in summer, spring, fall, and winter. The vines covering the entire structure seems to consume the house in the summer and then fade away over the winter, representing the growth of vegetation as a symbol of time. I think this idea can also be pushed farther and become a type of biomimicry as well as the example of green walls you were previously discussing. Although the vines are not mimicking a form of nature, they are already a true form of life, the house becomes a symbol of growth and time through the vegetative covering.