Sonoma’s Quarryhill Botanical Garden inagurates lecture series

“We sometimes say we’re Sonoma’s best-kept secret,” said William McNamara, president of the Quarryhill Botanical Garden, just outside of Glen Ellen. He’s risen through the ranks of the world-renowned biological institution, from assistant director to director to executive director to his current role as president. He even lives on the property, with his wife Joanna, as they have for 17 years.

While he welcomes every visitor who comes to the 25-acre property on Highway 12, about 15,000 last year, he’d like to see twice that many discover the verdant, diverse and wholly unique assemblage of Asian plants that Quarryhill hosts. “I tell people you can’t really go wine tasting at 10 a.m. – but that’s a good time to walk through our gardens.” But it’s not just visitation numbers that he’s looking for: McNamara is in some ways trying to save the world.

Increasingly, the purpose of such botanical gardens as Quarryhill is not to show off exotic flowers, or create manicured pathways through colorful parks, but to assure the very survival of plants in danger of extinction – extinction brought on by the rapacious success of one animal in particular: homo sapiens. “If current trends continue, many biologists are convinced that we will lose half of all plant and animal species by the end of this century,” said McNamara. “This is obviously a terrible tragedy for future generations and may affect our ability to survive as well.”

Touring the 25-acre estate, founded on the burned-over grounds of a former quarry, is a soft adventure in subtlety, of colors, textures and even aromas. Magnolias with leaves the size of serving platters loomover the graveled trails; smooth sensuous trunks gracefully pose in the understory; secret blossoms of subtly-colored iris rise like snake-heads from the duff; a variety of maple, once thought extinct in the wild – acer pentaphyllum, with five narrow leaflets that bears a coincident resemblance to cannabis – are among the 2,000 species of Asian native plants at Quarryhill, nearly all grown from seed in the nursery.

McNamara, now 65, came to Quarryhill just months after it was launched, in 1987 by Jane Davenport Jansen. Despite his B.A. in English literature, he soon found himself drawn to botany. Though he missed Quarryhill’s first seed-gathering expedition to China in 1987, he’s been on every one since.

A recent one took him once more to Yunnan, in the western quadrant of China, a country rich in unique species of maples, magnolias, dogwoods, rhododendrons, lilies, roses and many of the other plants we may think of as “ornamentals.” One tree of specific interest to McNamara is what he terms “that rare and curious maple,” acer pentaphyllum. It was first cataloged by Joseph Rock, an eccentric self-taught botanist who scoured western China for decades, and whose work forms an outline for much of Quarryhill’s collection.

The five-leaved maple is in danger of extinction in its native country, due in part to the construction of dams on the Yalong River. It grows well at Quarryhill, however, where a conservation grove of about 200 trees was planted in 2010. From here, seeds and plants have been widely distributed to many other botanic gardens and arboreta.

Increasingly, the role of botanical gardens has shifted from research and education, if not the novelty of exotics, to conservation. Quarryhill shares this mission with a number of other botanic gardens world-wide, such as the original garden Otro Botanico in Piza, Italy; the Royal Botanic Gardens, Kew, near London; U.S. Botanic Garden near Washington D.C., among many others. There are in fact some 1,800 botanical gardens in 150 countries, but having one of the quality and proximity of Quarryhill is a remarkable feather, or flower, in the cap of Sonoma Valley.

As part of the mission to bring more people to Quarryhill, to help underwrite their expenses and mission through memberships, events and donations, they are inaugurating the Peter H. Raven Summer Lecture Series this month, with the first of three summer lectures featuring award-winning naturalists.

First up, on Saturday June 25, is Peter Raven himself, president emeritus of the Missouri Botanical Garden, one of the oldest botanical institutions in the country and a man whom McNamara calls “perhaps the world’s most important conservation biologist.” He’s a frequent visitor and admirer of Quarryhill, and McNamara and the board of directors thought it would be fitting to name their lecture series after him.

Raven’s lecture, “Saving plants: What can botanical gardens contribute?” strikes at the heart of many places like Quarryhill that have become genetic refuges for plant species whose range and habitat are being decimated, first by direct human intervention and, more recently, by climate change.

Other lecturers in the series include, on July 23, Tony Kirkham, head of the world’s most famous arboretum, that at Royal Botanic Gardens, Kew; and on Aug. 20, Paul Ehrlich, probably best known for his controversial 1968 book “The Population Bomb,” who will discuss the “sixth great mass extinction,” one which could be brought upon life on earth not by falling comets, ice ages or restless volcanoes, but by the changes to the planet brought about humankind itself.

The lecture series, in the deep tradition of botanical gardens, is for the purposes of research and education and, increasingly, conservation. Because, as some botanists might say, the world these tens of thousands of plant species evolved in is being dramatically altered by the effects of one clever ape who is, perhaps, not so clever after all.

Contact Christian at christian.kallen@sonomanews.com.