Magnolia sect. Macrophylla, Michaux, 1803

García-Morales, Leccinum J., Iamonico, Duilio & Jiménez, Jesús García, 2017, Nomenclatural remarks on Magnolia sect. Macrophylla (Magnoliaceae), with description of a new species from North America (Tamaulipas, Mexico), Phytotaxa 309 (3), pp. 238-244 : 243

Key to species of Magnolia sect. Macrophylla

1. Trees with branching trunks; eastern USA, Florida ; 0‒150 m ................................................................................... Magnolia ashei

- Tree without branching trunks; not in Florida, eastern USA..............................................................................................................2

2. Flowers white with a dark blotch near base of the petals...................................................................................................................3

- Flowers white without a dark blotch on the petals.............................................................................................................................6

3. Leaf blades 25‒40 cm long; Mexico, Nuevo León; 1500‒1700 m ............................................................. Magnolia nuevoleonensis

- Leaf blades ≥ 50 cm long; except Nuevo León, Mexico...................................................................................................................4

4. Carpels 35‒42; Mexico (Tamaulipas; 1500‒1750 m) ....................................................................................... Magnolia alejandrae

- Carpels 44‒78; except Tamaulipas, Mexico.......................................................................................................................................5

5. Leaf blades 50‒110 cm long; USA, Alabama, Arkansas, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Ohio, Tennessee, Virginia; 150‒300 m ................................................................................................................................. Magnolia macrophylla

- Leaf blades 24‒70 cm long; eastern Mexico, Veracruz ; 1600‒1700 m ................................................................. Magnolia vovidesii

6. Stamens 420‒430; stamens 19‒21 mm long; carpels 80‒105; south Mexico, Oaxaca ; 1600‒1900 m) ............... Magnolia dealbata

- Stamens 290‒310; stamens 10‒15 mm; carpels 50‒65; central-eastern Mexico, Hidalgo, Queretaro, San Luis Potosi ; 1800‒1950 m).................................................................................................................................................................. Magnolia rzedowskiana