Our national flower is the concrete cloverleaf.

In this quote, Lewis Mumford uses the phrase "concrete cloverleaf" to critique the increasing dominance of infrastructure and urbanization in modern society. The "national flower" metaphorically represents what has become a symbol of the country—specifically, the overreliance on concrete and highways as the foundation of urban life. Mumford is lamenting the way that modern architecture and urban planning have prioritized functionality over natural beauty, suggesting that the sprawling network of highways and interchanges has replaced the simpler, more organic symbols of the land, like flowers.

Mumford’s remark is a commentary on how technological and industrial advancements, such as the creation of interstates and highways, have reshaped the landscape. The cloverleaf, which refers to the shape of many highway interchanges, is used ironically here to show how what was meant to facilitate progress has instead become a symbol of overdevelopment and environmental degradation. The "flower" once associated with nature has now been replaced by an emblem of man-made progress, which Mumford suggests is not as enriching or fulfilling as it might seem.

The origin of the quote comes from Lewis Mumford, an influential American historian, philosopher, and sociologist. Mumford was known for his critical writings on the relationship between technology, society, and urban planning. His works often emphasized the importance of human-scale development and the dangers of unchecked technological progress. This quote exemplifies his belief that the modern world’s focus on industrial growth and technological efficiency often comes at the expense of the environment and the inherent beauty of nature.