Developed in Germany, the CityTree is a mobile structure that incorporates mosses and urban furniture to create a possible solution to the polluted air of urban centers.

Eight CityTrees in front of the Frauenkirche in Dresden, Germany. Image © Green City Solutions

Developed in Germany, the CityTree is a mobile structure that incorporates mosses and urban furniture to create a possible solution to the polluted air of urban centers.Rectangular, trunkless and flat, this "tree" basically consists of a large vertical panel, a wall of mosses which, according to its creators, has the capacity to absorb the same amount of nitrogen dioxide and microscopic particles from the air as 275 natural trees.Each CityTree can absorb 250 grams of particles per day and stores 240 metric tons of CO2 per year, say its creators. Installation takes about 6 hours and maintenance is quite simple, since the structure has built-in sensors that control the air temperature, water quality, and soil moisture. The sensors also allow the air quality to be measured in order to evaluate the efficiency of the structure.
Eight CityTrees in front of the Frauenkirche in Dresden, Germany. Image © Green City Solutions

Despite CityTree's promising qualities, one of the product's setbacks is its cost. Planting and maintaining a traditional tree costs cities less than $1,000 per decade, while just purchasing a CityTree costs about $25,000, prompting the question: would it not be ...