During my morning commute along the 110 Freeway to LAist’s Pasadena office, I often pass by beige concrete sound walls meant to shield nearby neighborhoods from the noise of traffic.
However, on a recent drive, I noticed a vibrant display of yellow flowers cascading over these sound walls, illuminating the early light.
Curiosity sparked within me as I pondered how plants could survive and even thrive in such a harsh, urban environment.
To find out more, I harnessed my journalistic instincts and delved deeper into the story behind this resilient vine.
Since the Cahuenga Pass Freeway opened in 1940, residents of Los Angeles have expressed concerns about highway noise, leading to the construction of sound walls for relief.
The first sound wall was built in Milpitas along Interstate 680 in 1968, and now, as of 2023, approximately 338 miles of sound walls can be found throughout Los Angeles and Ventura Counties according to Caltrans’ office of environmental engineering.
These sound walls are a collaborative effort between L.A. Metro and the State Department of Transportation, with the maintenance handled by Caltrans.
After snapping a photo of the walls adorned with yellow flowers during my drive and sending it to a Caltrans representative, I learned that the plant in question is known as Dolichandra unguis-cati, commonly referred to as ‘cat’s claw’ vine.
In their response, the Caltrans spokesperson invited me to reach out with further inquiries, and I had many.
Researching cat’s claw brought up alarming reports, particularly an article from a university lab that labeled the vine as “showy but invasive” and described it as a “major nuisance” illegal to sell or buy in Florida.
Erik Blank, a horticultural educator at the nonprofit Theodore Payne Foundation, emphasized the negative ecological impact of invasive plants.
“Invasive plants don’t support our local fluttering and crawling species — birds, bees, butterflies, caterpillars,” Blank explained.
He noted that invasive species often outcompete native plants that are crucial for local wildlife.
Originating from the West Indies and parts of Central and South America, cat’s claw has proliferated in various regions globally, even reaching Australia and China.
A USDA report indicated that cat’s claw could potentially spread to around 20% of the United States, highlighting its adaptability.
While Blank admires the resilience of such plants, he cautioned against introducing them without careful consideration.
I remembered this caution during a subsequent commute when I noticed the cat’s claw vine had overtaken part of a highway sign, partially obscuring the message: “____ WORK AHEAD.”
Meanwhile, at the University of California, Davis, researcher Alessandro Ossola investigates ways that plants can enhance urban environments.
Ossola’s research includes exploring the cooling effects of vines in cities.
“The beauty of vines is that they grow fast — much faster than a tree,” he shared, pointing out that vines could serve as a quick solution for urban greening, offering shade while waiting for trees to mature.
He acknowledged that cat’s claw thrives in urban landscapes due to its low water requirement, contrasting with Florida’s moist climate which may contribute to its invasive tendencies there.
Interestingly, cat’s claw is not classified as an invasive species in California, and Ossola suggested that Southern California’s drought conditions may help manage its growth.
“We need to change the narrative regarding plant care,” he mentioned. “Plants can beautify our cities and provide various benefits, but they require maintenance.”
He advocated for a diverse landscape in urban settings, where multiple plant species coexist, ensuring ecological balance even if some become invasive.
In response to my inquiries, Caltrans’ regional landscape architecture team clarified that cat’s claw vine was planted around 1996, a peak period for sound wall construction, when the aesthetic shortcomings of concrete walls were becoming increasingly apparent.
The stark expanse of concrete walls created an opportunity for artistic expression, but they also radiated heat and detracted from community aesthetics.
Caltrans explained that various vines were tested to identify which would thrive in the harsh conditions commonly found in freeway environments, including wind and high temperatures.
Regarding concerns about the vine’s potential invasiveness, Caltrans noted, “Almost any plant, whether native or non-native, can be considered invasive in a pristine environment if introduced.”
They assured me that routine maintenance helps keep cat’s claw’s growth under control.
Despite their careful management, Caltrans could not provide records of where else cat’s claw has been planted in the area.
The spokesperson indicated that there had been a few instances of the vine’s removal due to construction, and it hasn’t been replanted in over two decades.
For my part, I find comfort and joy in the bright yellow flowers gracing my regular commute, reminding me of the resilience of nature.
The colorful display serves as a symbol that a thriving environment can emerge from the most unexpected places, showcasing the intersection of urban development and the vitality of the natural world.
image source from：https://laist.com/news/los-angeles-activities/los-angeles-110-freeway-yellow-flowers-sound-wall-cats-claw
