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 southern Virginia 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. It typically has a single stem (or trunk) and a pyramidal shape. 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, 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.

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.

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".

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, evergreen magnolia, large-flower magnolia or big laurel are alternative names. The timber is known simply as magnolia.

M. grandiflora fruit

Distribution and habitat

Southern magnolias are native to the Southeastern United States, from southeast Virginia 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. It is killed by summer fires, and is missing from habitats that undergo regular burning.

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. Despite preferring sites with increased moisture, it does not tolerate inundation. It grows on sand-hills in maritime forests, where it is found growing with live oaks and saw palmetto. 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.

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. Squirrels, opossums, quail, and turkey are known to eat the seeds.

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. It was glowingly described by Philip Miller in his 1731 work The Gardeners' Dictionary. 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).

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.

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.

In the interior of the US, some of the cold-hardy cultivars have survived north to the southern Ohio Valley (southern 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.

It is recommended for seashore plantings in areas that are windy but have little salt spray. The foliage will bronze, blotch, and burn in severe winters at the northern limits of cultivation, especially when grown in full winter sun, 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.

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, and they have been used in decorative floral arrangements. The leaves have a waxy coating that makes them resistant to damage from salt and air pollution.

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. Its use in the Southeastern United States has been supplanted by the availability of harder woods.

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. Many older cultivars have been superseded by newer ones and are no longer available. Some cultivars have been found to be more cold hardy, they include:

• 'Bracken's Brown Beauty', developed by Ray Bracken of Easley, South Carolina, in the late 1960s, is a popular cultivar which has survived long-term in southern Ohio, West Virginia, New Jersey, and Long Island, NY. This cultivar grows in a dense and compact pattern, with narrow, medium-sized, glossy leaves. Flowers measure 5–6 in (13–15 cm).
• 'Edith Bogue' was brought to the coastal plain of New Jersey from Florida in the 1920s. The original tree sent to Edith A. Bogue from Florida helped to establish cold-hardy specimens in the Middle Atlantic states from Delaware to coastal Connecticut. Once established, 'Edith Bouge' has been known to have only minor spotting and margin burn on the leaf in temperatures as low as −5 °F (−21 °C). With a vigorous classic pyramidal shape, this cultivar grows to 35 ft with a 15-ft spread.
• 'Angustifolia', developed in France in 1825, has narrow, spear-shaped leaves 20 cm (7.9 in) long by 11 cm (4.3 in) wide, as its name suggests.
• 'Exmouth' was developed in the early 18th century by John Colliton in Devon. It is notable for its huge flowers, with up to 20 tepals, and vigorous growth. Erect in habit, it is often planted against walls. The leaves are green above and brownish underneath. The flowers are very fragrant and the leaves are narrow and leathery.
• 'Goliath' was developed by Caledonia Nurseries of Guernsey, and has a bushier habit and globular flowers of up to 30 cm (12 in) diameter. Long-flowering, it has oval leaves which lack the brownish hair underneath.
• 'Little Gem', a dwarf cultivar, is grown in more moderate climates, roughly from Maryland and the Virginias southward. Originally developed in 1952 by Steed's Nursery in Candor, North Carolina, it is a slower-growing form with a columnar shape which reaches around 4.25 m (13.9 ft) high and 1.2 m (3.9 ft) wide. Flowering heavily over an extended period in warmer climate, it bears medium-sized, cup-shaped flowers, and has elliptic leaves 12.5 cm (4.9 in) long by 5 cm (2.0 in) wide.

Other commonly grown cultivars include:

• 'Ferruginea' has dark-green leaves with rust-brown undersides.
• 'Southern Charm' has large oval leaves, bushy habit, and smaller growth. It is also known as 'Teddy Bear'.

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. The leaves contain coumarins and sesquiterpene lactones. The sesquiterpenes are known to be costunolide, parthenolide, costunolide diepoxide, santamarine, and reynosin.

Gallery

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  Magnolia grandiflora (southern magnolia) – a large tree at Hemingway, South Carolina

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  Bark on trunk

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  Southern magnolia foliage and flower

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  A cluster of leaves

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  Before the opening act

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  Inside the flower

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  Seed cluster of M. grandiflora

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  From below

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  Martin Johnson Heade: Magnolia

External links

• Magnolia grandiflora Magnolia Grandiflora from Audubon's Birds of America
• Magnolia grandiflora images at bioimages.vanderbilt.edu