Beloved by gardeners and florists for the fragrant large white flowers that occur in spring and summer warmth, the southern magnolia also has large, glossy leaves with alluring undersides that are a fuzzy rusty brown in color. Native to the coastal plain of the deep South in the United States, southern magnolia today is widely grown as an ornamental tree in USDA winter hardiness zones 6b through 9.
The southern magnolia, like all other magnolia species, is considered one of the more primitive types of flowering plants. Thus, the southern magnolia is considered an angiosperm by botanists. Moreover, the fact that the seed of this plant germinates with two embryonic leaves (cotyledons) and produces a branching vein pattern in its foliage makes it a dicot.
The southern magnolia is logically placed in the magnolia family, Magnoliaceae. This family is further broken down into two subfamilies, Magnolioideae and Liriodendroideae. Southern magnolia is a member of the former (as are other magnolias), and the latter subfamily comprises the tulip trees.
Distinction Among Other Magnolias
All magnolias are placed in the genus Magnolia, including the southern magnolia tree. There are over 125 different species of magnolias worldwide, and taxonomists further segregate these plants by common genetic lineages, geographic origins or other characteristics. The southern magnolia is subsequently classified as being in subgenus Magnolia and section Magnolia. Although this sounds redundant, the subgenus and section designations keep the southern magnolia among similar plants that are not in the subgenera named either Yulania or Gynopodium. There are seven other sections in the Magnolia subgenus, according to the Magnolia Society International Online.
Finally, to distinguish the southern magnolia from any other closely related plant in the section Magnolia, it is given the species epithet (name) of Magnolia grandiflora. A species means the plant breeds with itself in the wild to produce like offspring.
Because the southern magnolia possesses many ornamental features, man has been growing this tree for generations. Thus, horticulturists have selected seedlings or other mutations that display a beneficial characteristic, such as a shorter mature growth size, larger flowers or better tolerance to cold or soil types. These cultivated (man-selected) varieties are most often called "cultivars." Examples of southern magnolia cultivars include 'Little Gem,' 'Edith Bogue,' 'D.D. Blanchard,' 'Brackens' Brown Beauty' and 'Goliath.' Cultivars are propagated asexually (such as by branch cuttings) to retain the genetic materials that create the unique qualities of each.