Its beauty is so mysterious, so rare, it stops you in your tracks. The big leaf magnolia, with its expansive white flowers and foot-wide leaves the size of canoe paddles, has captivated visitors to Polly Hill Arboretum for years. Polly Hill grew it from seed and was so awestruck that she named the tree after her husband, Julian Hill.
Magnolias have been on earth for a long time. The fossil record dates their origins back over 100 million years. In 1984 paleobotanists David Dilcher and Peter Crane discovered a fossilized plant in central Kansas, whose preserved flower and fruit bore a striking resemblance to those of modern magnolias. They named it Archaeanthus (first flower). In fact, many scientists agree that the magnolia was one of the first flowering plants to appear on earth after the long domination of ferns, tree ferns and conifer trees. While these earlier plant groups relied on wind dispersal of their spores or pollen, magnolias are one of the first documented plants to utilize insect-attractive pollen.
With their large pollen-rich anthers, magnolias offer an abundant food source to beetles, another species with an ancient past; they were the first insect pollinators of flowering plants. Currently, the arboretum’s big leaf magnolia is loaded with beetles foraging deep within the giant blooms. Each year when school children visit the arboretum, gender roles inevitably reveal themselves. The girls react squeamishly, while the boys pull the beetles off the flowers and place them in the girls’ hair or on their necks. But soon the shouting subsides and eyes widen as their attention is drawn to the colossal blooms. The interdependence of plants and animals, a bond stretching back over 100,000 million years, dawns on them.
The big leaf magnolia (Magnolia macrophylla) is native to southeastern North America. The largest tree recorded to date is found from the Daniel Boone National Forest in Tight Hollow, Ky. The tree stands just over 100 feet tall.
Magnolias are primarily a temperate group of trees, flourishing in environments that have a distinct change of seasons. Many live a precarious life, endangered in their natural habitats due to logging, grazing or natural resource exploitation. The big leaf magnolia is endangered in two southern states, the result of forest fragmentation. Sadly, they’re becoming increasingly rare in other parts of their natural range.
Many of our most unique trees at the arboretum are the result of Polly Hill’s insistence on growing trees from seed. She believed that plants grown from seed would reveal their true genetic potential. It was long believed by most horticulturists that the big-leaf magnolia would not survive this far north. Many of her seedlings became established and flourished. Her pragmatic nature and unwillingness to compromise resulted in the world-renowned collection of plants at the arboretum today.
The Julian Hill big leaf magnolia at the arboretum blooms from the middle of June to the end of July, and later in the fall, immense fruits form with striking red seeds.
Tim Boland is executive director of the Polly Hill Arboretum in West Tisbury.