Loebner's Magnolia

Family: Magnoliaceae
Latin Name: Magnolia loebneri 
'Merrill'
Common Name(s): Loebner's Magnolia, Merrill Magnolia

Deciduous or Evergreen: Deciduous
Native Range: Japan
USDA Hardiness Zone: 4-9
Mature Height: 20-30'
Mature Spread: 20-40'
Bloom Time: Late spring
Native to Minnesota: No
Shade Tolerant: Partial

Description:

The 'Merrill' cultivar of Loebner's Magnolia is a hybrid magnolia that is one of the few cold hardy magnolias.  Leaves are simple, alternate, obvate, and glossy, but the tree is best known for its floriferous, white blooms.  The tree usually grows with mutliple trunks and has smooth gray bark.  

Loebner's Magnolia is a cross between Magnolia kobus and Magnolia stellata, two Japanese magnolia varieties.  Max Loebner, a German horticulturist, made the first cross in the early 1900s, and noted that the new hybrid had better cold hardiness than many other magnolias.  Some organizations do not recommend planting the tree below a USDA hardiness zone of 5, but numerous trees at the Minnesota Lanscape Arboretum have survived the Minnesota winter.  

This particular tree is the only example of Loebner's Magnolia on the University of Minnesota's campus, but there are numerous specimens at the Minnesota Landscape Arboretum.  

Issues:

As mentioned, Loebner's Magnolia is only marginally hardy in Minnesota, so particularly cold winters can damage the trees.  Additionally, late spring frosts can kill freshly opened, delicate flower buds.  Magnolia scale and verticillium wilt can also be a problem.

Other Resources:

Minnesota Landscape Arboretum Magnolia Collection

Missouri Botanical Garden