Life and Death in the Plant World

The Polly Hill Arboretum, at the forefront of horticultural experimentation on Martha’s Vineyard, just keeps on planting.

The “dead file” at the Polly Hill Arboretum is four times the size of the “live file.” Tim Boland, the arboretum’s executive director since 2002, says this with a straight face. After all, everything dies – sooner or later. Plants, like animals, live with the constant threat of disaster. Predators, illness, accidents, or just a bad storm can all do in a plant faster than you can say “rhododendron.” Most of the plants in the arboretum’s “dead file” never made it past infancy, let alone childhood. Others, like the arbor woven of hornbeam trees that was a favorite fixture in the arboretum’s landscape for decades, lived long and thriving lives, but eventually senesced (the botanical term for growing old) and died. “It is always a matter, my darling / of life or death, as I had forgotten,” wrote Richard Wilbur in his poem “The Writer.” People whose job it is to keep things alive rarely forget it.

And although the arboretum’s founder led a flourishing life for half a century in her oversized “garden,” Polly Hill – an indefatigable and ubiquitous presence on the arboretum’s grounds even after it became an independent nonprofit organization in 1997 – eventually passed away in 2007 at the age of one hundred. Now, a dozen years after its nonprofit establishment, the arboretum’s goal is to keep her legacy alive, while also keeping up with the times.

A practical gardener

Mary Louise Butcher Hill, known as Polly, created the arboretum in 1957 at the age of fifty on a sixty-acre piece of West Tisbury property inherited from her parents. Having developed an interest in foreign plant species – particularly rhododendrons – while in Japan, and having done some coursework in botany and horticulture, she decided to use her land to find out what sorts of non-native plants could grow and thrive on what she called the “horticulturally impoverished” Vineyard.

A practical gardener who learned mainly through trial and error, Polly soon found that plants grown from seed were more likely to survive and thrive than were cuttings or transplanted specimens. Plants grown from seed develop better resistance to pests, diseases, and weather patterns common to their habitat. Hence Polly did almost all of her planting from seed. As a result, she learned the virtue of patience and the thrill of its eventual rewards, as when, for example, a seed-grown Stewartia finally flowered after twenty-nine years.

“Polly was prepared for things to conk out and just not make it,” says Linda McGuire of Vineyard Haven, an arboretum volunteer since 2001 who knew Polly personally. “She wasn’t emotionally involved with her plants, but rather, curious about how things worked. That’s what makes a great botanist: the ability to accept what life is, knowing that death is an inevitable part of it – to accept this not with dread, but with an adventuresome outlook.”

Tim concurs: “We follow Polly’s philosophy,” he says. “‘Just keep planting.’”

Today the arboretum continues to do most of its planting from seed. “You lose a lot of plants when they’re young and vulnerable,” says Tim, “but when they make it, it’s spectacular and totally worth it. It’s the victories you really grasp onto.” And the arboretum is chock full of victories – more than 3,350 individual trees, bushes, and perennials, comprising 1,683 different types (or taxa) of plants. These include most of the sixty cultivars that Polly herself named, among them a big-leaf magnolia she named for her husband – Magnolia macrophylla ‘Julian Hill’.

The science of survival

New cultivars happen when plants mutate, explains Tom Clark, the arboretum’s collections and grounds manager: Their leaves might change shape, their blossoms change color, or a dwarf version develops. When this occurs, whoever discovers the new cultivar gets to name it. Magnolia macrophylla ‘Julian Hill’ was considered new because it was a tree that had never before survived outside of the warmer weather of the Deep South. The one that Polly grew here from seed was unique, because it had the hardiness necessary to survive in our frostier climate.

Right now, the arboretum has three potential new naming opportunities in the pipeline. One is an American holly with unusually large red fruit. Last year, a touring group from the Holly Society of America, which was having its annual meeting on the Island, noticed this feature and pointed it out to the arboretum’s staff, who have since sent cuttings to holly experts around the country. If everyone agrees that the size of this holly’s fruit is truly bigger than your average berry, the Vineyard will boast a new, one-of-a-kind tree.

Preserving its meadows and woodlands and the plants that grow there continues to be a primary component of the arboretum’s mission – and a challenging one. As everyone knows, evolution is about the survival of the fittest, and for every plant that makes it, there are a handful that don’t. And what happens to be fittest is always in flux, as new threats pop up without warning in the habitat around a plant. The recent caterpillar blight that affected the entire Island, for example, killed off 40 percent of the oaks in the arboretum’s wild forest holdings. At Polly Hill, the infestation began in 2005 and finally waned in 2008, with the worst damage in 2006 and 2007 when the trees were weakened from drought.

Over the next fifteen years, Dr. David Foster, director of Harvard Forest, will lead a study of the arboretum’s affected regions. By recording changes in new growth, temperature, the release of nitrogen, etcetera, and by sampling sediment in freshwater ponds (allowing them to piece together a flora history spanning thousands of years), researchers hope to determine whether there is a link between climate change and insect blights like the recent one.

A much-mourned casualty at the arboretum was the pleached (that is, interwoven) hornbeam arbor, sometimes called the “tunnel of love.” Weakened by diminishing sunlight as the trees around it grew, it succumbed to an attack by borer insects. Another arboretum favorite, the dogwood allée, is now threatened by both scale (an insect that sucks fluids from its host) and anthracnose disease (a fungus that can cause early defoliation). Arboretum staff members are combating these dangers by removing and destroying fallen, infected leaves, and by aerating the soil around the trees, whi ch gets impacted by foot traffic.

Pines and spruces at the arboretum have suffered recently, because monoculture pine planting in the Island’s state forest brought bugs and pathogens that have since infected other areas of the Island. (Fortunately, they don’t affect the firs that are native to the Vineyard.) Similarly, a type of lilac that was clustered together in one area at the arboretum was nearly lost to a stem borer wasp; moving some plants that seemed resilient to other locations saved this particular lilac and taught the staff an important lesson: Placing plants of the same type in more than one location from the outset reduces the chance of losing that type of plant altogether.

Continuing to thrive

Fortunately it’s not all about fending off the Grim Reaper at Polly Hill. There are multiple notable success stories, many of them rooted in Polly’s practice of planting from seed. While Polly planted many seeds that people sent to her from other parts of the country and abroad, the arboretum’s new practice, when possible, is to go to the point of origin to collect seeds. Staff members have made four expeditions to Georgia, North Carolina, and other parts of the southeastern United States, and two to Japan. Collecting seeds where they grow makes it possible to choose the heartiest of specimens, and also, according to Tim Boland, increases the chance of finding something new and unusual – such as a mutated version of a plant.

Another change has been the acquisition in 2002 of a ten-acre adjacent property on State Road. This brought the arboretum’s total holdings to seventy acres and gave it a place to build a greenhouse for nurturing seedlings. The greenhouse provides a more controlled environment in which seedlings can be protected against hazards such as animals and early frosts. “Polly didn’t have this,” says Tim, “but she always wanted one.”

Among the plants grown in the new greenhouse is a tree native to the southeastern United States called Franklinia alatamaha, named for both Benjamin Franklin and a river in Georgia. This particular tree has been extinct in the wild since the early 1800s, but it is cultivated by horticultural institutions around the country that have rare plant conservation and preservation among their goals. Closer to home is the arboretum’s trademarked MV Wildtype program, launched in 2006, which aims to produce native Vineyard plants from seed collected in the wild on the Island, and provide these plants (through sales) to the community. By encouraging greater use of native plants – particularly to prevent fragmentation of habitat – the program also seeks to fend off species extinction.

In conjunction with MV Wildtype, the arboretum is recording the location of native plants in the wild using information gathered when collecting point-of-origin seeds. With global information system (GIS) digital technology, the arboretum can pinpoint plants in the wild within a ten-foot radius. Over time, the organization hopes to have a complete map, available on the Internet, of all the wild flora on the islands that make up Dukes County.

Tim wants the arboretum’s name shouted from the rooftops, but, he says, “We’re still suffering from ‘best-kept secret on the Island syndrome.’” Linda McGuire says Vineyarders tend to get caught up in their own little worlds and can overlook the Island’s natural treasures. “Think of how few people you see when you’re out on the Island’s walking trails,” she points out. “We just don’t think of ourselves as having something of this kind of national prominence.”

One way the arboretum is working to promote itself is through its education programs. With walking tours of the property, an adult lecture series, and on-site classes for about five hundred Island schoolchildren a year, the arboretum seeks to teach the public not only about the ornamental value of plants in the landscape, but also about the importance of plants in the web of life. Particularly given the lure of computers and electronics, says Tim, “getting kids into nature is huge.” By nurturing kids’ interest in the natural world, he adds, “we hope to create a generation of new Pollys.”

Linda teaches workshops for school groups and says the program’s goal is not just to familiarize children with the arboretum, but also to give them a sense of the life that is surging all around them. She tells a story of coming across Polly, sitting in the cart she drove around the property, just after a rainstorm: “She didn’t turn around as I approached,” says Linda, “but she must have sensed I was there. She said, ‘Isn’t it just beautiful? Doesn’t it smell just wonderful?’ This is what we want for the kids and our other visitors – an awareness of life that includes the drops of rain on the leaves and the smells of the different pines scenting everything.”

Tim and other arboretum staff are also working hard to increase membership (currently 650) and the number of visitors to the property (13,600 in 2009). The organization has created several free events to bring in newcomers, including an annual solstice celebration, a series of wintertime walks, and a class on identifying native plants.

In the meantime, quietly and with determination, the organization carries on, evolving while preserving the original goals of its founder, and always, always following her simple but critical advice: “Just keep planting.”