The Connecticut countryside faces invading hordes — of plants, and Yale’s landscaping is complicit in the onslaught, said ecologists from the Yale School of Forestry & Environmental Studies.

Yale’s plants include nonnative species that take over local ecosystems. These invasive species drive out plants and animals that do belong in these ecosystems and can eventually upset the water table and wildfire patterns. While Yale Facilities controls the growth of its invasive shrubs and trees on campus, the plants produce seeds that birds and winds distribute miles away in green space vulnerable to invasion.

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The problem, said Ann Camp, lecturer in stand dynamics and forest health, is that Connecticut countryside has no natural control mechanisms for nonnative species. So the state must step in to protect its land. Since 1998, Connecticut plant nurseries may no longer sell over 100 species of blacklisted foreign plants.

The list pits the interests of the horticultural industry and ecologists against each other, said Camp, because invasive species have sold well to landscape contractors and homeowners alike who appreciate their resilience; nevertheless, they threaten overall habitat health.

“Many of the species are staples of their industry,” she added.

She said she believes that the lobbying power of the horticultural industry kept the banned plants list brief. However few they may be, some of these outlaws still thrive within Yale’s greenery.

The presence of invasive species on campus is disturbing to environmental health specialists, said Camp.


Yale stated in its recently released Sustainable Strategic Plan that the university will experiment with native plants on campus within the next three years. As long as Yale continues to seek LEED certification for its landscaping, the university will need to strategically choose native plants for placement on the campus grounds.

Efforts to cleanse urban habitats of invasive plants sometimes take the form of personal vendettas, Camp explained.

Until last week, an invasive Burning Bush plant that was thirty feet long and rose above eye-level grew outside the Global Institute for Sustainable Forestry in Marsh Hall. But on Oct. 18 Camp’s colleague brought out a chainsaw and chopped it down, she said.

Camp said the University planted invasives like the large shrub before they were banned.

One building over from Kroon Hall, which selected native plants for its courtyards, the Burning Bush’s red leaves hide an entire side of Sage Hall, a sight that angered some students.

“The forestry school shouldn’t keep things that are ecologically dangerous outside their door,” Marlyse Duguid FES ’10 said.

The problem lies in a lack of communication between the School and Yale Landscaping, Camp said.

Duguid explained that many professors involve themselves in local efforts for plant removal rather than campus-based ones.

“We’re not as involved with what Mother Yale does,” Camp said.


Adding green spaces to urban areas is always positive — even when it involves foreign plants, Eric Larson, director of Marsh Botanical Gardens, said. Any plant helps cool the city and clean its air, he noted.

Invasive species make popular city plantings for precisely the reasons that they prove dangerous to delicate ecologies, Larson said. They are hardier and their foliage often lasts later into fall than native species, allowing them to store more energy than their native neighbors, he explained.


A changing climate and a mobile population allow new invasive species to become threats quickly.

Camp pointed to the Japanese Stiltgrass that recently appeared along the stairs leading to Marsh Botanic Gardens. In just the last few years it has spread from the Mid-Atlantic states to New England.

But Camp’s current target is the destructive Asian long-horned beetle, which is destroying New England’s maple trees.

In Massachusetts, the beetle has become a federal concern; USDA officials will remove infected trees on private and public lands with or without the owner’s permission in order to protect Vermont’s maple syrup industry, Duguid explained.

Back in New Haven, the Yale campus is having enough trouble with the Japanese stiltgrass and Norway maple trees.

Thankfully, Camp said, the beetles have yet to arrive.