Native plant species on highway rights-of-way are sometimes planted as monocultures. As an example, here are hundreds of plants of the same species, Quadrella cynophallophora, Jamaica caper. Maintenance workers prune the plants, square as board.
If you continue east a few hundred feet, you’ll find a different native shrub species, in mass, similarly squared off on top and both sides.
The Florida DOT specified that I-595 Corridor Roadway Improvements Project included, “low-maintenance, native or naturalized plants well suited to the microclimate where they are installed.”
Designers defined plant species diversity as:
- at least 3 unique species of large trees
- 2 species small trees
- 2 palm species
- 5 shrub species
The Florida DOT objective was “development of native landscapes.” But they did not mention planting layout, whether interspersed or in solid masses.
We can judge the results of board-square monocultures as incongruous with “native landscapes.” But we must be aware of bigger challenges.
Practical considerations
Florida Department of Transportation and other public transportation entities have gradually improved the safety and esthetics of highway roadsides. They have tried to increase plant species diversity and compatibility with surroundings. But lofty goals of wildflower restoration and reducing mowing costs must meet the engineering and maintenance challenges of transportation, which is the purpose of roadways.
Detailed specifications in highway design are needed for safety and accountability. Because these are complex, it is challenging to make specifications adapt to local conditions. Every project would need a different set of specifications. Different species of plants naturally grow in different soils and climates, interspersed with one another. Can a contractor agree to maintain a right-of-way landscape if similar plants are not grouped in mass?