One of the pleasures of my job as communications manager for the Arboretum Foundation is taking photographs of the plant collection, which we use in our publications and social media. Most of the time during the year, there’s always plenty of good photographic subject matter—from the cherries, azaleas, and rhodies in spring to the wonders of the Witt Winter Garden in the late season.
There is one time of year, however, when the floristic pickings can seem a little bit slim: the heart of summer. (When I worked at Brooklyn Botanic Garden, we would tell visitors that midsummer is the time to enjoy the cooling shade of the lush, green foliage. Translation: Sorry, most of the flowering trees and shrubs have already done their thing!) But there are always summer treasures to find in the Arboretum, if you know where to look.
One of my favorite trees to visit in summer is the southern sweetbay, Magnolia virginiana var. australis. We have two, fine, big specimens along Azalea Way, one almost directly across the trail from the Hybrid Rhododendron Garden and the other a little further north, on top of the hill south of the Woodland Garden. From June to mid-July (and sporadically till first frost), the trees bear beautiful, two- to four-inch wide, cup-shaped white flowers with a delicious, lemony fragrance.
Magnolia virginiana var. australis is the southern form of the sweet bay or swamp magnolia (M. virginiana), which is native to the eastern U.S., from New York south to Florida and west to eastern Texas. Current taxonomy lumps the two varieties together, but they have some notable differences: Southern sweetbay grows somewhat taller, has more fragrant flowers, and is more likely to be evergreen.
It’s easy to make the comparison in the Arboretum. That’s because the specimen of southern sweetbay near the rhody garden is flanked on its west side by four specimens of its northern cousin. All the trees have two-toned leaves: glossy, medium-green on top, and pale, silvery green on the bottom. The foliage flutters easily when hit by a breeze, creating a shimmering effect.
The northern variety can be a suckering shrub or small tree growing between 15 and 30 feet. The southern sweet bay can reach 50 feet in cultivation and almost double that in the wild. In the cluster by our rhody garden, the northern trees are all around 25 feet tall, while the southern sweet bay is about 30 feet tall, despite being about 20 years younger than its cousins.
Although both varieties are wetland plants, they’re adaptable to drier soil, as long as it’s somewhat acidic. The plants also adapt well to full sun or partial shade. After their showy display, the flowers develop into cones of orange-red fruits that are prized by a variety of birds and other wildlife.
Our two southern sweetbays were both received as seed from the University of Illinois Horticulture Department in 1966. The rhody garden tree was planted out in 1978, while the Woodland Garden tree was planted the following year.
Our trees have interesting parentage, says University of Washington Botanic Gardens Curator Ray Larson. The seed came from a cross between trees at Urbana, Illinois and Turtletown, Polk County, Tennessee. According to a letter sent to then Arboretum director Brian Mulligan, the Turtletown trees were reputed to have exceptionally glossy leaves for the species.
Niall Dunne is the editor of the “Bulletin” and the communications manager at the Arboretum Foundation.
—Originally published in the Arboretum Bulletin, Summer 2017
