May 2022 - Sweetbay Magnolia
Common Name: Sweetbay magnolia. Has numerous alternate names, including laurel, laurel magnolia, swamp magnolia, swampbay, southern sweetbay, white-bay, and white-laurel.
Botanical Name: Magnolia virginiana
Native Range: Found in freshwater swamps, on borders of ponds and streams, and in other wet areas of southeastern United States in Hardiness Zones 5 to 10. Its range lies in the coastal plains from east Texas across to the Atlantic, and extends in the piedmont as well as the coastal plains from Florida north up though New Jersey; but is only rarely found north of New York.
Height: Princeton is near the northern edge of its range, and here it usually grows only to about 20’ tall. (In the U.S. south, it may reach as much as 60'.)
Spread: Can grow either as a small tree with a spreading, rounded crown, 10’-15’wide, or as a shorter, suckering, open, multi-stemmed shrub. In the south its crown can open up to 35’ wide.
Form: As a single-stemmed tree, takes on a graceful slender pyramidal form; as a multi-stemmed shrub, has an open, spreading habit.
Growth Rate: Medium to fast growth rate.
Sun: Grows in full sun to partial shade.
Leaf Description: Alternate, simple, entire, oblong-lanceolate leaves, 3-6” long and 1-1 2/3” wide, and leathery. Dark green, often lustrous on upper surface; silvery beneath. Dirr writes: “the foliage is handsome as the wind buffets the leaves exposing the silvery underside….”
Fall Color: Sweetbay magnolia is semi-evergreen. Its green leaves persist longer than most, but most turn yellow or bronze tinged and fall by mid-winter.
Flower Description: A number of solitary flowers (showy, 2-3" in diameter, creamy white, and waxy) with a “sweet,” “lemony” fragrance appear in May to June; blossoms may continue to emerge sporadically through the summer and into September. The flowers are cup-shaped, formed of 9-12 petals, and are pollinated by beetles attracted to their pollen.
Fruit: Upright, 2” long, cone-like aggregate fruits comprised of two-seeded, berry-like drupes that form within jacketed pods. As they mature, the pods split and peel back in the fall to reveal the showy red or pink skin of the seed inside.
Bark Description: Twigs are slender bright green and hairy when young and later become bright red-brown with pale lenticels. On main stems bark is smooth and pale gray, becoming somewhat scaly with age.
Wildlife Benefit: A plant host to up to 21 species of moths and butterflies, including the Sweetbay silkmoth (Callosamia securifera). As a consequence, birds are attracted to sweetbay magnolia as a source of caterpillars to feed their chicks. Also, the fruits of sweetbay are a food source for a variety of birds – woodpeckers, tanagers, grosbeaks, cardinals and finches.
Tolerates: Heavy clay soils, wet or boggy sites, air pollution, shade
Possible Insects: No serious insect problems. Might on occasion have leaf miner.
Possible Disease: No serious disease problems.
- It’s an attractive native ornamental popular for its fragrant flowers borne over a long period and showy conelike fruit. Can be used as a specimen tree for lawns or as a tall multi-stemmed shrub for shrub borders or foundation plantings.
- Suitable for rain gardens.
Where to be found on municipal property: A mature specimen of “Sweetbay glauca” may be found in Marquand Park. On the locator map near the park entry off the parking lot on Lover’s Lane, the key indicates that this specimen is to be found at F, 6. The variety ‘glauca’ is bushier than the straight species of Magnolia virginiana and has semi-double flowers rather than the usual single blooms. In addition, newly planted sweetbay magnolia can be found around the parking lot area that serves the Mountain Lakes House
- Magnolias have fat fleshy roots. Sweetbay were called "Beaver tree" by colonists who used the roots to bait traps for caatching beavers.
- Easily grown. Needs little to no maintenance.
- Does require acid soil; leaves will develop chlorosis in alkaline soils.
- At least a half dozen selections are commercially available, including a dwarf form that only grows to 8’ tall.
Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. http://bonap.net/MapGallery/County/Magnolia%20virginiana.png
Martine, Christopher, Trees of New Jersey and the Mid-Atlantic States, Forest Education Resource Center, NJ Department of Environmental Protection, 4th Edition, 2000.
Dirr, Michael A., Manual of Woody Landscape Plants, Their Identification, Ornamental Characteristics, Culture, Propagation and Uses, 5th Edition, Stipes Publishing L.L.C., 1998.
Lady Bird Johnson Wildflower Center
Butterflies and Moths of North America, https://www.butterfliesandmoths.org/species/Callosamia-securifera
Kim Brand, Bird-Friendly Communities Coordinator, Audubon North Carolina. https://nc.audubon.org/news/sweetbay-magnolia-adding-life-your-garden
Cullina, William, Native Trees, Shrubs, & Vines, The New England Wild Flower Society, 2002.
Sandra Chen, April 2022