{{Short description|Species of tree}} {{more footnotes needed|date=June 2017}} {{Speciesbox | name = Bigleaf magnolia | image = MagnoliaMacrophylla.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 20 November 2021">{{cite iucn |author=Global Tree Specialist Group |date=2014 |title=''Magnolia macrophylla'' |volume=2014 |article-number=e.T62595A3116514 |doi=10.2305/IUCN.UK.2014-1.RLTS.T62595A3116514.en |access-date=20 November 2021}}</ref> | genus = Magnolia | display_parents = 2 | parent = Magnolia sect. Macrophylla | species = macrophylla | authority = [[André Michaux|Michx.]] | range_map = Magnolia macrophylla range map.jpg | range_map_caption = Natural range }}
'''''Magnolia macrophylla''''', the '''bigleaf magnolia''', is a [[deciduous]] [[magnolia]] native to the southeastern [[United States]]. This species boasts the largest simple [[leaf]] and single [[flower]] of any native woody plant in North America.
==Classification== ''Magnolia macrophylla'' is currently considered monotypic, with no subspecies or varieties.<ref name="POWO">{{cite POWO |title=''Magnolia macrophylla'' Michx. |id= 30417720-2 |access-date=2025-07-16}}</ref> In the past, it was often treated as having two subspecies, subsp. ''ashei'' and subsp. ''dealbata'', but these are now treated as separate species, ''[[Magnolia ashei]]'' in Florida,<ref name="POWO2">{{cite POWO |title=''Magnolia ashei'' Weath. |id= 149272-2 |access-date=2025-07-16}}</ref> and ''[[Magnolia dealbata]]'' in eastern Mexico.<ref name="POWO3">{{cite POWO |title=''Magnolia dealbata'' Zucc. |id= 280259-2 |access-date=2025-07-16}}</ref>
==Description== The bigleaf magnolia is a medium-sized understory [[tree]] {{cvt|15|–|20|m}} tall, though some individuals over 27 m tall (and over 100 cm circumference)<ref>See thread on an ENTS trip report in Roswell, GA here: http://www.ents-bbs.org/viewtopic.php?f=73&t=2133</ref> have been documented by the [https://web.archive.org/web/20110225183236/http://nativetreesociety.org/ Eastern Native Tree Society]. This species is distinguished from other magnolias by the large [[leaf]] size, {{cvt|24|–|60|cm}} (rarely to {{cvt|100|cm}}) long and {{cvt|11|–|26|cm}} (rarely to {{cvt|32|cm}}) broad, with a stout {{cvt|5.5|–|15|cm}} [[petiole (botany)|petiole]].<ref name="Hunt">{{cite book | last=Hunt | first=David | title=Magnolias and their allies | publisher=International Dendrology Society & Magnolia Society | publication-place=Milborne Port, Sherborne, UK | date=1998 | isbn=0-9517234-8-0 | pages=92–93}}</ref> The tree's branches often bend under the weight of this heavy foliage. The flowers typically have nine [[tepal]]s (sometimes only six), with three whorls of three tepals each, the larger ones with a purple spot at the base. The tepals are typically about {{cvt|14.5|–|20.5|cm}} long and {{cvt|5|–|14|cm}} wide.<ref name="Hunt"/> It is, like all Magnolias, beetle pollinated. The fruit is a cone-like cluster of achenes {{cvt|5.5|–|8|cm}} long.<ref name="Hunt"/> The mature seeds, each covered with an orange [[aril]], hang down from the cone on silk-like threads, making themselves readily available to passing birds.
===Bee mortality=== At the Arnold Arboretum, dead bees have been observed inside bigleaf magnolia flowers. However the bees in cited article are honeybees which are not native to North America.<ref>{{cite magazine |title=Seeing Life—Re-engaging with nature |author=William Friedman |date=March 2021 |magazine=[[Harvard Magazine]] |url=https://harvardmagazine.com/2021/03/features-seeing-life-arnold-arboretum |access-date=February 25, 2021}}</ref>
==Distribution and habitat== Bigleaf magnolia is found in rich [[Mesic habitat|mesic]] woods; any disturbance that lets more light reach the ground is beneficial to the establishment of bigleaf magnolia, but despite its relatively fast growth-rate when stimulated by more light, other understory and canopy trees/seedlings are usually able to outgrow and out-compete it. This suits the plant just fine as it is tolerant of low light levels; it does not need full sun to survive once established (however, it does not tolerate full shade). Natural regeneration is quite limited due to the scarcity of mature, seed-bearing plants and the fact that this tree's population mostly consists of widely scattered individuals. In addition, this species is plagued by poor seed set (most likely from limiting factors mentioned above) and low seed [[:wikt:viable|viability]], a trait shared by its cousin and frequent associate in the wild in [[Appalachia]], the ''[[Magnolia fraseri|Fraser magnolia]]''.
In the southeastern United States, especially [[Alabama]] and surrounding areas, ''Magnolia macrophylla'' is sometimes called the "cowcumber magnolia", in contrast with the much smaller-leaved [[Magnolia acuminata|cucumber-tree magnolia]], ''M. acuminata''.{{cn|date=July 2025}}
==Threats== Collection, both legal and illegal, may have an adverse impact on this tree's population due to low [[population density]], and high [[Collecting|collection]] pressure can [[Local extinction|extirpate]] this species locally. Bigleaf magnolia is listed as [[threatened]] in [[North Carolina]] and [[endangered]] in [[Arkansas]] and [[Ohio]].
==Cultivation== Bigleaf magnolia is often short-lived under cultivation unless its rather demanding requirements are met. This tree likes loose, undisturbed rich mesic soil (or mulch and compost substitutes) in full sun or part shade with moist, well-drained soil and a low pH.<ref>{{Cite book|title=Trees for the South|last=Hastings|first=Don|publisher=Longstreet Press|year=2001|isbn=1-56352-596-8|location=Atlanta, Georgia|page=109}}</ref> This tree will likely succeed in sites that closely mimic its natural habitat and where it is protected from strong wind that can tatter its large foliage. It can be grown farther north than its southerly range suggests, but needs watering during extended dry periods. This plant is generally problem-free.
==Gallery== <gallery widths="230" heights="200" mode="packed"> File:Magnolia macrophylla bigleaf magnolia.JPG|Young tree in North Chickamauga Creek, Tennessee File:Magnolia macrophylla ssp. macrophylla flower.jpg|Open flower File:Magnolia macrophylla ssp. macrophylla fruit.jpg|Mature fruit File:Magnolia macrophylla ssp. macrophylla.jpg|At bud break File:Magnolia macrophylla ssp. macrophylla leaves.jpg|Leaves in fall File:BigLeafMagnoliaFruitUnripe.jpg|An unripe fruit. File:MagnoliamacrophyllaNCS.jpg|Large specimen growing on [[North Carolina State University|NCSU]] campus. File:Magnolia macrophylla tree AA.jpg|''Magnolia macrophylla'' 1989 accession (#960-89*A), Arnold Arboretum of Harvard University File:Bigleaf Magnolia Magnolia macrophylla Sapling 1550px.jpg|A sapling planted in the Tyler Arboretum File:Bigleaf Magnolia Magnolia macrophylla Leaf 2500px.jpg|A single leaf on the above sapling File:BigleafMagnoliaHighline.jpg|A northerly specimen planted on NYC's [[High Line|Highline]]. </gallery>
==References== {{Reflist}}
==External links== {{Commons category|Magnolia macrophylla}} *[https://arboretum.harvard.edu/plants/image-search/?keyword=Magnolia+macrophylla&submit=Search ''Magnolia macrophylla'' images at the Arnold Arboretum of Harvard University Plant Image Database] *Hetman, Jon. [https://arboretum.harvard.edu/stories/hunnewell-building-spring-magnolia-1986/ "Magnolia macrophylla".] Arnold Arboretum of Harvard University website, 13 May 2019. Accessed 20 April 2020. *Friedman, William (Ned).[https://arboretum.harvard.edu/stories/killer-magnolias/ "Killer magnolias".]''Posts from the Collections,'' Arnold Arboretum of Harvard University website, 20 July 2019. Accessed 20 April 2020. *[http://www.michaux.org/magnolia.htm An ecological study of Magnolia macrophylla in Gaston County, NC] *[https://web.archive.org/web/20080604141716/http://www.cas.vanderbilt.edu/bioimages/species/frame/mama2.htm ''Magnolia macrophylla'' images at bioimages.vanderbilt.edu] *[https://web.archive.org/web/20070927143223/http://www.fnai.org/FieldGuide/pdf/Magnolia_ashei.PDF Field Guide to the Rare Plants and Animals of Florida Online: Magnolia ashei] *[http://www.treetrail.net/magnolia.html Magnolia macrophylla Distribution Map] *[http://www.plantmaps.com/nrm/magnolia-macrophylla-bigleaf-magnolia-native-range-map.php Interactive Distribution Map of ''Magnolia macrophylla''] *[http://www.ents-bbs.org/viewtopic.php?f=73&t=2133]
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[[Category:Magnolia|macrophylla]] [[Category:Endangered flora of the United States]] [[Category:Trees of Northern America]] [[Category:Garden plants of North America]] [[Category:Ornamental trees]]