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Bigleaf Magnolia

Bigleaf Magnolia (Magnolia macrophylla)

FAMILY: Magnoliaceae 
 
DESCRIPTION: Small tree to 18 m., flowering late May-June.  
 
SIMILAR SPECIES: Very similar to Magnolia tripetala, but differing in a number of characters. M. macrophylla has leaves auricled at base and terminal buds pubescent, M. tripetala has leaves tapered to base and terminal buds glabrous. Also similar to M. acuminata, which has smaller non-auricled leaves and pubescent terminal buds. Other than these species it is unlikely to be confused with any other tree in Ohio. M. macrophylla has the largest entire leaves of any woody plant in Ohio, often reaching 9 dm. in length.  
 
TOTAL RANGE: Widely scattered throughout the southeastern United States: cent. KY and TN to NC, GA, AL, MS, LA, and ne. AR; disjunct in s. OH.  
 
STATE RANGE: There are post-1990 records from Jackson County.  
 
HABITAT: In Ohio, found both in mesic wooded ravines and near the tops of these ravines in oak woods.  
 
THREATS: Opening of the canopy by logging operations. This tree is apparently unable to tolerate direct sunlight.  
 
RECOVERY POTENTIAL: Unknown.  
 
INVENTORY GUIDELINES: The leaves and buds of this species are sufficient for identification; the very few populations should not be disturbed.  
 
COMMENTS: This plant is at the northern edge of its range on the Allegheny Plateau. Its Ohio distribution is along a major tributary of the pre-glacial Teays river, and very possibly reached Ohio in pre-glacial times by seeds carried along this river. Its distribution in Ohio is well known, and it is doubtful that new locations of this very obvious plant will be found.  
 
This plant has interesting adaptations to insure cross-pollination.  It is pollinated by beetles, which feed on various flower parts (Thien, 1974).  
 
SELECTED REFERENCES:  
 
Rockwell, H.C., Jr. 1966. The genus Magnolia in the United States.  M.A. Thesis, West Virginia University, Morgantown, WV. 93 p.  
 
Thien, L.B. 1974. Floral biology of Magnolia. Am. J. Bot. 61: 1037-1045. 

UPDATED 12/2020

For more information:

Division of Natural Areas and Preserves

614-265-6453