Nina Bassuk's favorite trees

Oaks have long been a focus of her work so whittling down is hard, but Bassuk likes Swamp White Oak (Quercus bicolor, above) for its transplanting ease. As the common name suggests, this species is suited for wet soil, but is also drought tolerant.

“I like a lot of Cotinus. There are some great color variants plus they’re incredibly drought tolerant.”

Also known as smokebush or smoke tree, she’s particularly fond of the European (C. coggyria, above left) and American species (C. obovatus above right) for their pumpkin orange fall color. “They look extraordinary and are tough.”

“It’s underutilized, but a great tree for lots of different situations alkaline and acid, and drought tolerant,” she said.  Gymnocladus dioicus (above) is dioecious, meaning each tree is either male or female.

Hawthorns (Crataegus spp.) are smaller trees with multi-season interest of white flowers in late spring and red berries in winter (above left). In particular, Bassuk likes the somewhat deer-resistant ‘Winter King’ (C. viridis ‘Winter King’ above right).

Glorious elms (Ulmus spp.) have taken a beating due to diseases, but there is hope for those with the space for these great shade trees. Bassuk points to newer hybrids that are disease resistant like Triumph™. The hybrid 'Frontier' (above left) shows good resistance to Dutch elm disease and elm yellows. 'Accolade' (above right) is reportedly resistant to elm yellows and elm leaf beetle.

Dogwoods, like the Kousa (Cornus kousa, above left), are always popular for their wonderful flowers and colorful fruit. With similar flower power, cherries are also a favorite and Bassuk recommends the ‘Accolade’ hybrid (Prunus ‘Accolade’ above right).

While her work has focused more on deciduous species, Bassuk does have some favorite evergreens. “Eastern Red Cedar, Juniperus virginiana, is our native plant (above). The ‘Grey Owl’ hybrid is really useful for plantings around the Cornell campus.”

Eastern white pines (Pinus strobus) have experienced declines in recent years and Bassuk finds Limber pine (P. flexilis above) to be a good alternative.

On firs, she notes the Nordmann (Abies nordmanniana, above) to be very adaptable and underutilized in the landscape. She’s also fond of Korean fir (A. koreana) with the bright white undersides of the needles (above right), but cautions that it needs the right site with acid to neutral soil

The changing landscape

While there may be many favorites, there’s one thing Bassuk dislikes: monocultures.

“It’s a big problem particularly in urban areas where people have overplanted the same species like London Planetree. That opens potential for disease or insect problems when there’s so much of one thing. Diversity is the key,” she said.

Over the years, Bassuk has been a leader in changing such single species landscapes and is pleased with how planting styles have started to evolve.

“What’s come to the foreground now are the ecosystem services and benefits to people trees provide.”

To help her students better understand the wide array of trees available for landscaping Bassuk created the Woody Plants Database. This searchable website with more than 500 profiles of trees, shrubs, vines, and groundcovers also helps horticulture professionals and homeowners match the right plant to their landscape.

“People can learn about plants they might not be as familiar with and start incorporating them to their sites to create a diverse planting palette,” she said. “The database shows how the plant will look through the year. Spring flowers may be the cherry on top, but they only last a few weeks. There are all kinds of other factors that make a plant beautiful, like form and fall color.”

But Bassuk offers a reminder: any plant is only as good as the soil it goes into. “You can have the best tree in the world, but if the soil is lousy, you’re going to have a lousy plant.”

Reflecting on a legacy

As her final academic year ends, it’s unclear how Cornell will continue her valuable work after she leaves. “Woody plant material has been taught since 1888. I’ve built upon that over these years, and I’d like to see someone take it on and make it their own. There’s a lot that they can build on.”

Like many retirees, Bassuk plans to spend more time gardening. But her goal, like the trees she loves, is loftier than simply tending a few vegetables. Along with an occasional speaking engagement, she’ll develop a nursery on her property, focusing on shrubs that are not available commercially but offer great value. As an emeritus faculty member Bassuk will also continuing to do research, especially developing her range of hybrid oaks which began in 2004, though the propagation work has proven challenging.

“It takes a long time to develop a tree.”