When Mary Gibson Henry packed her bags for a three-month stay in a remote area of northeastern British Columbia with her husband, her children and her dog, she saved room for a record player.
A movie camera that also made the 1931 trip captured evidence of the record player in a sailboat carrying a lounging Mrs. Henry as she explored a tropical valley filled with native plants.
That archival film footage began my visit to the Henry Foundation for Botanical Research in Gladwyne, Pennsylvania. The remote 40-acre site, tucked away in one of Philadelphia’s Main Line neighborhoods, was the home of Mrs. Henry (1884-1967), a botanist and plant explorer who traveled the world tracking down unique plants, collecting them and incorporating them in her garden for study and enjoyment.
Mrs. Henry’s granddaughter, Susan Treadway, introduced me to this intrepid traveler who climbed the Massif du Mt. Blanc in Chamonix, France and hiked the North American wilderness during 90 expeditions over a 40-year period. Mount Mary Henry, one of British Columbia’s Rocky Mountains, was named in Mrs. Henry’s honor.
Mrs. Henry taught herself how to identify plants and press herbarium specimens, collecting thousands of them on horseback and in chauffeur-driven cars to send to the Academy of Natural Sciences at Drexel University in Philadelphia, among other repositories.
Her handsome home, built in the Norman English style in 1926, contains a library of about 1,000 volumes. William Robinson’s The Wild Garden prompted Mrs. Henry to create a garden on the steeply sloping land of her Gladwyne farm. First published in 1870, the book encouraged a naturalistic approach to gardening by arranging native plants according to local growing conditions and then letting them thrive on their own, rather than constantly maintaining them in rigid geometrical designs.
After reading William Bartram’s 1791 classic, Travels through North and South Carolina, Georgia, East and West Florida, she was inspired to retrace Bartram’s steps and look for the native Flame azaleas in full bloom on a hillside along the Savannah River, a sight with red and orange colors so intense that he thought the hillside was on fire. That led her to seek wild native plants endangered by their changing native habitats, rescue them, and transplant them to places in her garden where she thought they would thrive so they could be admired and used for research. Plants from southern gardening zones, but at the northern limits of their ranges, held a special fascination for her. Experimenting with propagating and crossing these plants led her to develop improved specimens such as Itea virginica (Henry’s Garnet), that have been introduced in today’s northern gardens.
Mrs. Henry was fascinated with rare and unusual species of plants, such as those with darker foliage and double flowers. Her sharp eye led her to discover Lilium iridollae MG Henry (Pot-of-Gold Lily), Braya henryae Raup (Northern Rock Cress), Castilleja henryae Pennel (Magenta Paintbrush), Chamaecyparis henryae Li (Atlantic White Cedar), Chionanthus henryae Li (Fringe Tree), Antenarria megacephala Fern (Pygmy Pussy-toes), Hymenocallis choctawensis, H. henryae, H. moldenkiana, H. palusvirensis, H. pygmaea Traub (Spider Lily), Phlox floridana Benth, ssp. bella Wherry (Florida Phlox), and Stewartia x henryae Li (Henry’s Stewartia).
While weeding in her garden, Mrs. Henry discovered an evergreen hedge plant with rich green foliage that displays bright yellow flowers in the spring and brilliant reddish-bronze leaves in the fall. Patented by one of her nurserymen, it is known as Berberis x gladwynensis “William Penn” (William Penn Barberry).
To propagate her finds, Mrs. Henry first put her plants in a 30′-by-30′ trial garden, then moved three specimens at most to the regular garden. Orchids resided in a 6–by-8′ greenhouse. She documented what she planted and how they grew.
An expert at siting plants, Mrs. Henry placed her treasures where she thought they would do best. She created landscapes featuring continuing blooms and distinctive fragrances, as we experienced when we took whiffs of spicy-smelling bayberry leaves and the lemony leaves of the alyssum. She grew many plants that would provide food for birds. Most meaningful to modern gardeners, she was ahead of her time in favoring low-maintenance, self-sustaining plantings.
Mrs. Henry’s garden features 200 to 300 species of newly discovered woody plants from Asia that she planted; Stewartia monadelpha trees from China that she grew from seeds she ordered in the 1930s; every species of magnolia native to North America; ivy brought from the Baltic; a Florida Cedar she claimed was a new species; Carolina silverbell; and a Burkwood viburnum given to her by Mr. Burkwood himself, according to Mrs. Treadway. At least one plant from each state is represented in the garden.
Looking at a lush rhododendron growing near the house, Mrs. Treadway proclaimed, “I’ve never seen it at such perfection.”
Mrs. Henry formed her foundation to preserve, research and educate others about native plants. After her death, her daughter, Josephine, continued cataloging her collections; her granddaughters and others continue the effort today. The garden has been open to the public since 1974.
For more on the Henry Foundation for Botanical Research, read Gardens of Philadelphia and the Delaware Valley, by William M. Klein, Jr.