Bigleaf magnolia
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 Big Leaf Magnolia
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| Magnolia macrophylla Michx. |
The Bigleaf Magnolia (Magnolia macrophylla) is a deciduous magnolia native to the southeastern United States and eastern Mexico.
[edit] Physical characteristics
The plant is medium-sized understory tree 15-20 m tall, distinguished from other magnolias by the large leaf size, 25-80 cm long and 11-30 cm broad. Many of the tree's branches bend under the weight of the large foliage. This species boasts the largest simple leaf and single flower of any native plant in North America.
Bigleaf Magnolia is very rare and widely scattered in the wild; few people have seen it except in cultivation.
This tree is found in rich 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 like 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 scatterd individuals. In addition, this species is plagued by poor seed set (most likely from limiting factors mentioned above) and low seed viability, a trait shared by its cousin and frequent associate in the wild, Fraser magnolia.
Plant collection, both legal and illegal, may have an adverse inpact on this tree's population due to low population density, and high collection pressure can cause this species to locally disappear.
There are three subspecies; the latter two have been treated as separate species by some botanists:
- Magnolia macrophylla subsp. macrophylla. Bigleaf Magnolia. Southeastern United States. secure. Tree to 20 m; leaves 50-90 cm long, fruit 4-10 cm long with more than 50 carpels.
- Magnolia macrophylla subsp. ashei (Wetherby) Spongberg. Ashe Magnolia. Northwest Florida. EN. Shrub or small tree to 12 m; leaves 25-60 cm long, fruit 4-5 cm long with less than 50 carpels.
- Magnolia macrophylla subsp. dealbata (Zuccarini) J. D. Tobe. Mexican Bigleaf Magnolia. Mexico (Hidalgo to Oaxaca and Vera Cruz, in cloud forests). DD. Tree to 20 m; leaves 30-60 cm long, fruit 8-15 cm long with more than 70 carpels.
The Ashe Magnolia is a rare shrub, exceptionally a small tree, that is found only along the bluffs and ravines adjacent to the Apalachicola River, along with several other rare plants unique to the area, such as Florida Yew. It resembles the typical subsp. macrophylla, but has shorter, broader leaves, smaller flowers, and longer fruit. The 6 to 8-inch diameter flowers occur in late spring and are white with rose-purple blotches on the inner tepals. The Florida Department of Agriculture lists the Ashe magnolia as endangered due to its small population and restricted range. The fruit is eaten by wildlife, but because of the plant's scarceness, it does not form a significant portion of any creature's diet.
This species is often short-lived under cultivation unless its rather picky requirements are met. This tree likes loose, undisturbed rich mesic soil (or mulch and compost substitutes) in full sun or part shade with plenty of moisture. This tree will likely succeed in sites that closely mimic its natural habitat and where it is protected from strong wind which can tatter its large foliage. It can be grown farther north than its southernly range suggests. Water during extended dry periods. This plant is generally problem free.
