Magnolia grandiflora

Southern magnolia
Magnolia grandiflora (southern magnolia)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Magnoliids
Order: Magnoliales
Family: Magnoliaceae
Genus: Magnolia
Subgenus: M. subg. Magnolia
Section: M. sect. Magnolia
Species: M. grandiflora
Binomial name
Magnolia grandiflora
L.

Magnolia grandiflora, commonly known as the southern magnolia or bull bay, is a tree of the family Magnoliaceae native to the southeastern United States, from coastal North Carolina to central Florida, and west to East Texas and Oklahoma. Reaching 27.5 m (90 ft) in height, it is a large, striking evergreen tree with large, dark green leaves up to 20 cm (7.9 in) long and 12 cm (4.7 in) wide, and large, white, fragrant flowers up to 30 cm (12 in) in diameter. Although endemic to the lowland subtropical forests on the Gulf and south Atlantic coastal plain, magnolia grandiflora is widely cultivated in warmer areas around the world. The timber is hard and heavy, and has been used commercially to make furniture, pallets, and veneer.

Description

Flower and foliage of M. grandiflora

Magnolia grandiflora is a medium to large evergreen tree which may grow 120 ft (37 m) tall.[1] It typically has a single stem (or trunk) and a pyramidal shape.[2] The leaves are simple and broadly ovate, 12–20 cm (4.7–7.9 in) long and 6–12 cm (2.4–4.7 in) broad,[2] with smooth margins. They are dark green, stiff and leathery, and often scurfy underneath with yellow-brown pubescence. The large, showy, lemon citronella-scented flowers are white, up to 30 cm (12 in) across and fragrant, with six to 12 petals with a waxy texture, emerging from the tips of twigs on mature trees in late spring. Flowering is followed by the rose-coloured fruit, ovoid, 7.5–10 cm (3.0–3.9 in) long, and 3–5 cm (1.2–2.0 in) wide.[3]

Exceptionally large trees have been reported in the far southern United States. The national champion is a specimen in Smith County, Mississippi, that stands an incredible 37 m (121 ft). Another record includes a 35-m-high specimen from the Chickasawhay District, De Soto National Forest, in Mississippi, which measured 17.75 ft in circumference at breast height, from 1961, and a 30-m-tall tree from Baton Rouge, which reached 18 ft in circumference at breast height.[3]

Taxonomy

Magnolia grandiflora was one of the many species first described by Linnaeus in his Systema Naturae in 1759, basing his description on the earlier notes of Miller. He did not select a type specimen. Its specific epithet is derived from the Latin words grandis "big", and flor- "flower".[4]

M. grandiflora is most commonly known as southern magnolia, a name derived from its range in the Southern United States. Many broadleaved evergreen trees are known as bays for their resemblance to the leaves of the red bay (Persea borbonia), with this species known as the bull bay for its huge size or alternatively because cattle have been reported eating its leaves. Laurel magnolia,[4] evergreen magnolia,[3] large-flower magnolia or big laurel are alternative names.[5] The timber is known simply as magnolia.[3]

M. grandiflora fruit

Distribution and habitat

Southern magnolias are native to the Southeastern United States, from coastal North Carolina south to central Florida, and then west to East Texas and Oklahoma. It is found on the edges of bodies of water and swamps, in association with sweetgum (Liquidambar styraciflua), water oak (Quercus nigra), and black tupelo (Nyssa sylvatica). In more sheltered habitats, it grows as a large tree, but can be a low shrub when found on coastal dunes.[6] It is killed by summer fires, and is missing from habitats that undergo regular burning.[7]

In Florida, it is found in a number of different ecological areas that are typically shady and have well-draining soils; it is also found in hummocks, along ravines, on slopes, and in wooded floodplains.[8] Despite preferring sites with increased moisture, it does not tolerate inundation.[3] It grows on sand-hills in maritime forests, where it is found growing with live oaks and saw palmetto.[7] In the eastern United States, it has become an escape, and has become naturalized in the tidewater area of Virginia and locally in other areas outside of its historically natural range.[9]

Ecology

Individual seeds

Magnolia grandiflora can produce seed by 10 years of age, although peak seed production is achieved closer to 25 years of age. Around 50% of seeds can germinate, and they are spread by birds and mammals.[3] Squirrels, opossums, quail, and turkey are known to eat the seeds.[10]

Cultivation and uses

The plant collector Mark Catesby, the first in North America, brought M. grandiflora to Britain in 1726, where it entered cultivation and overshadowed M. virginiana, which had been collected a few years earlier. It had also come to France, the French having collected it in the vicinity of the Mississippi River in Louisiana.[11] It was glowingly described by Philip Miller in his 1731 work The Gardeners' Dictionary.[12] One of the earliest people to cultivate it in Europe was Sir John Colliton of Exeter in Devon; scaffolding and tubs surrounded his tree, where gardeners propagated its branches by layering, the daughter plants initially selling for five guineas each (but later falling to half a guinea).[12]

Tree planted 1807 at Jardin des plantes in Nantes
Catesby's Laurel tree of Carolina by G.D. Ehret

It is often planted in university campuses and allowed to grow into a large tree, either with dependent branches, or with the lower branches removed to display the bare trunks. It is also espaliered against walls, which improves its frost-hardiness.[4]

United States cultivation

Magnolia grandiflora is a very popular ornamental tree throughout its native range in the coastal plain of the Gulf/South Atlantic states. Grown for its attractive, shiny green leaves and fragrant flowers, it has a long history in the southern United States. Many large and very old specimens found in the subtropical port cities such as New Orleans, Mobile, Savannah, Charleston, and Wilmington, NC. M. grandiflora is the state tree of Mississippi and the state flower of Louisiana.

The species is also cultivated in the warmer parts of the United States; On the East Coast, a small number of specimens can be found growing as far north as coastal areas of New Jersey, Connecticut, and Long Island, NY. Farther south, it is grown more widely in Delaware, much of the Chesapeake Bay region in Maryland, and much of eastern Virginia. On the West Coast, it can be grown as far north as British Columbia/Seattle area, though cooler summers on the West Coast slow growth compared to the East Coast.[4]

In the interior of the US, some of the cold-hardy cultivars have survived north to the southern Ohio Valley (Ohio, Kentucky, southern Indiana). Farther north, few known long term specimens are found due to the severe winters, very cold temperatures, and/or lack of sufficient summer heat.

Magnolia grandiflora is also grown in parts of Mexico, Central America, and South America as well as parts of Asia.[4]

It is recommended for seashore plantings in areas that are windy but have little salt spray.[13] The foliage will bronze, blotch, and burn in severe winters at the northern limits of cultivation, especially when grown in full winter sun,[14] but most leaves remain until they are replaced by new foliage in the spring. In climates where the ground freezes, winter sun appears to do more damage than the cold. In the Northern Hemisphere, the south side of the tree will experience more leaf damage than the north side. Two extremes are known, with leaves white underneath and with leaves brown underneath. The brown varieties are claimed to be more cold-hardy than the white varieties, but this does not appear to be proven as yet. Once established, the plants are drought tolerant, and the most drought tolerant of all the Magnolia species.[14]

The leaves are heavy and tend to fall year round from the interior of the crown and form a dense cover over the soil surface,[14] and they have been used in decorative floral arrangements.[15] The leaves have a waxy coating that makes them resistant to damage from salt and air pollution.[14]

In the United States, southern magnolia, along with sweetbay (Magnolia virginiana) and cucumbertree (Magnolia acuminata), is commercially harvested. Lumber from all three species is simply called magnolia, which is used in the construction of furniture, boxes, pallets, venetian blinds, sashes, and doors and used as veneers. Southern magnolia has yellowish-white sapwood and light to dark brown heartwood tinted yellow or green. The usually straight-grained wood has uniform texture with closely spaced rings. The wood is ranked moderate in heaviness, hardness, and stiffness, and moderately low in shrinkage, bending, and compression strength; it is ranked moderately high in shock resistance.[16] Its use in the Southeastern United States has been supplanted by the availability of harder woods.[17]

Cultivars

Over 50 cultivars have been developed and named in North America and Europe. Most plants in nurseries are propagated by cuttings, resulting in more consistent form in the various varieties available.[18] Many older cultivars have been superseded by newer ones and are no longer available.[19] Some cultivars have been found to be more cold hardy, they include:

Other commonly grown cultivars include:

Chemistry

M. grandiflora contains phenolic constituents shown to possess significant antimicrobial activity. Magnolol, honokiol, and 3,5′-diallyl-2′-hydroxy-4-methoxybiphenyl exhibited significant activity against Gram-positive and acid-fast bacteria and fungi.[22] The leaves contain coumarins and sesquiterpene lactones.[23] The sesquiterpenes are known to be costunolide, parthenolide, costunolide diepoxide, santamarine, and reynosin.[24]

References

  1. ↑ Gardiner, p. 144
  2. 1 2 Zion, Robert L. (1995). Trees for architecture and landscape. New York: Van Nostrand Reinhold. p. 224. ISBN 978-0-471-28524-3.
  3. 1 2 3 4 5 6 Maisenhelder, Louis C. (1970). "Magnolia" (PDF). American Woods FS-245. US Dept. of Agriculture. Retrieved 2009-11-05.
  4. 1 2 3 4 5 Callaway, p. 99
  5. ↑ Coladonato, Milo (1991). "Magnolia grandiflora". Fire Effects Information System, [Online]. Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).: U.S. Department of Agriculture, Forest Service. Retrieved 12 January 2010.
  6. ↑ Gardiner, p. 143
  7. 1 2 Whitney, Eleanor Noss; Rudloe, Anne; Jadaszewski, Erick. Priceless Florida: Natural Ecosystems and Native Species. Pineapple Press (FL). p. 36. ISBN 978-1-56164-308-0.
  8. ↑ Nelson, Gil; Marvin, Jr Cook. The Trees of Florida: A Reference and Field Guide (Reference and Field Guides (Paperback)). Pineapple Press (FL). p. 17. ISBN 978-1-56164-055-3.
  9. ↑ http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200008470
  10. ↑ Halls, L. K. 1977. Southern magnolia/Magnolia grandiflora L. In Southern fruit-producing woody plants used by wildlife. p. 196-197. USDA Forest Service, General Technical Report SO-16. Southern Forest Experiment Station, New Orleans, LA.
  11. ↑ Aitken, Richard (2008). Botanical Riches: Stories of Botanical Exploration. Melbourne, Victoria: Miegunyah Press: State Library of Victoria. p. 112. ISBN 0-522-85505-9.
  12. 1 2 Gardiner, p. 18
  13. ↑ Bush-Brown, Louise Carter; Bush-Brown, James; Irwin, Howard S. (1996). America's garden book. New York: Macmillan USA. p. 537. ISBN 0-02-860995-6.
  14. 1 2 3 4 Sternberg, Guy; Wilson, James; Wilson, Jim (2004). Native trees for North American landscapes: from the Atlantic to the Rockies. Portland: Timber Press. p. 268. ISBN 978-0-88192-607-1.
  15. ↑ Callaway, p. 13
  16. ↑ The Encyclopedia of Wood. Skyhorse Publishing. pp. 1–7. ISBN 978-1-60239-057-7.
  17. ↑ Callaway, p. 14
  18. 1 2 Gardiner, p. 145
  19. ↑ Callaway, p. 100
  20. 1 2 3 Gardiner, p. 147
  21. 1 2 Brickell, Christopher (1989). The American Horticultural Society encyclopedia of garden plants. New York: Macmillan. p. 51. ISBN 0-02-557920-7.
  22. ↑ Antimicrobial activity of phenolic constituents of magnolia grandiflora L. Alice M. Clark, Arouk S. El-Feraly, Wen-Shyong Li, Journal of Pharmaceutical Sciences, August 1981, Volume 70, Issue 8, pages 951–952, doi:10.1002/jps.2600700833
  23. ↑ Coumarins and sesquiterpene lactones from Magnolia grandiflora leaves. Yang MH, Blunden G, Patel AV, O'Neill MJ and Lewis JA, Planta medica, 1994, vol. 60, no 4, pages 390-390, INIST:11250251
  24. ↑ Isolation and characterization of the sesquiterpene lactones costunolide, parthenolide, costunolide diepoxide, santamarine, and reynosin from Magnolia grandiflora L. Farouk S. El-Feraly and Yee-Ming Chan, Journal of Pharmaceutical Sciences, March 1978, Volume 67, Issue 3, pages 347–350, doi:10.1002/jps.2600670319

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