The natural range of Magnolia species is a disjunct distribution, with a main center in east and southeast Asia and a secondary center in eastern North America, Central America, the West Indies, and some species in South America. Today many species of Magnolia and an ever-increasing number of hybrids can also be found as ornamentals in large parts of North America, Europe, Australia and New Zealand. The genus is named after French botanist Pierre Magnol. Known as kepelan in Indonesia, this wood is used for making furniture and carved panels and never for statues.
Magnolia is an ancient genus. Having evolved before bees appeared, the flowers developed to encourage pollination by beetles. As a result, the carpels of Magnolia flowers are tough, to avoid damage by eating and crawling beetles. Fossilised specimens of M. acuminata have been found dating to 20 million years ago, and of plants identifiably belonging to the Magnoliaceae dating to 95 million years ago. Another primitive aspect of Magnolias is their lack of distinct sepals or petals. The term tepal has been coined to refer to the intermediate element that Magnolia has instead. Magnolias are used as food plants by the larvae of some Lepidoptera species, including Giant Leopard Moth.
Magnolia grandiflora is the official state flower of both Mississippi and Louisiana. The flower's abundance in Mississippi is reflected in its nickname of "Magnolia State". The magnolia is also the official state tree of Mississippi.
Carolus Linnaeus, who was familiar with Plumier's Genera, adopted the genus name Magnolia in 1735 in his first edition of Systema naturae, without a description but with a reference to Plumier's work. In 1753, he took up Plumier's Magnolia in the first edition of Species plantarum. Since Linnaeus never saw an herbarium specimen (if there ever was one) of Plumier's Magnolia and had only his description and a rather poor picture at hand, he must have taken it for the same plant which was described by Catesby in his 1730 Natural History of Carolina. He placed it in the synonymy of Magnolia virginiana variety foetida, the taxon now known as Magnolia grandiflora.
The species that Plumier originally named Magnolia was later described as Annona dodecapetala by Lamarck, and has since been named Magnolia plumieri and Talauma plumieri (and still a number of other names) but is now known as Magnolia dodecapetala.
This work contains a drawing of a plant under the vernacular name Eloxochitl, that is most likely Magnolia macrophylla subsp. dealbata. It is possibly first-ever description of a Magnolia that was seen in the Western World. It is unclear whether there are early descriptions made by English or French missionaries who were sent to North America, but the first introduction of a Magnolia into Europe is well documented. It was the missionary and plant collector John Banister (1654-1693) who sent back Laurus tulipifera, foliis subtus ex cinereo aut argenteo purpurascentibus from Virginia in 1688, to Henry Compton, the Bishop of London. This species is now known as Magnolia virginiana (Sweetbay magnolia). Thus, a plant collector had shipped the first Magnolia from North America to Europe before Charles Plumier discovered his Talauma on Martinique and gave it the name Magnolia.
By the end of the 18th century, botanists and plant hunters exploring Asia began to name and describe the Magnolia species from China and Japan. The first Asiatic species to be described by western botanists were Magnolia denudata and Magnolia liliiflora, and Magnolia coco and Magnolia figo. Soon after that, in 1794, Carl Peter Thunberg collected and described Magnolia obovata from Japan and at roughly the same time Magnolia kobus was also first collected.
With the number of species increasing, the genus was divided into the two subgenera Magnolia and Yulania. Magnolia contains the American evergreen species Magnolia grandiflora, which is of horticultural importance, especially in the United States, and Magnolia virginiana, the type species. Yulania contains several deciduous Asiatic species, such as Magnolia denudata and Magnolia kobus, which have become horticulturally important in their own right and as parents in hybrids. Classified in Yulania, is also the American deciduous Magnolia acuminata (Cucumber tree), which has recently attained greater status as the parent which is responsible for the yellow flower colour in many new hybrids.
Relations in the family Magnoliaceae have been puzzling taxonomists for a long time. Because the family is quite old and has survived many geological events (such as ice ages, mountain formation and continental drift), its distribution has become scattered. Some species or groups of species have been isolated for a long time, while others could stay in close contact. To create divisions in the family (or even within the genus Magnolia), solely based upon morphological characters, has proven to be a nearly impossible task.
By the end of the 20th century, DNA sequencing had become available as a method of large scale research on phylogenetic relationships. Several studies, including studies on many species in the family Magnoliaceae, were carried out to investigate relationships. What these studies all revealed was that genus Michelia and Magnolia subgenus Yulania were far more closely allied to each other than either one of them was to Magnolia subgenus Magnolia. These phylogenetic studies were supported by morphological data.
As nomenclature is supposed to reflect relationships, the situation with the species names in Michelia and Magnolia subgenus Yulania was undesirable. Taxonomically there are three choices; 1: to join Michelia and Yulania species in a common genus, not being Magnolia (for which the name Michelia has priority); 2: to raise subgenus Yulania to generic rank, leaving Michelia names and subgenus Magnolia names untouched; or 3: to join Michelia with genus Magnolia into genus Magnolia s.l. (a big genus). Magnolia subgenus Magnolia can not be renamed because it contains Magnolia virginiana, the type species of the genus and of the family. Not many Michelia species have so far become horticulturally or economically important, apart for their wood. Both subgenus Magnolia and subgenus Yulania include species of major horticultural importance, and a change of name would be very undesirable for many people, especially in the horticultural branch. In Europe, Magnolia even is more or less a synonym for Yulania, since most of the cultivated species on this continent have Magnolia (Yulania) denudata as one of their parents. Most taxonomists who acknowledge close relations between Yulania and Michelia therefore support the third option and join Michelia with Magnolia.
The same goes, mutatis mutandis, for the (former) genera Talauma and Dugandiodendron, which are then placed in subgenus Magnolia, and genus Manglietia, which could be joined with subgenus Magnolia or may even earn the status of an extra subgenus. Elmerrillia seems to be closely related to Michelia and Yulania, in which case it will most likely be treated in the same way as Michelia is now. The precise nomenclatural status of small or monospecific genera like Kmeria, Parakmeria, Pachylarnax, Manglietiastrum, Aromadendron, Woonyoungia, Alcimandra, Paramichelia and Tsoongiodendron remains uncertain. Taxonomists who merge Michelia into Magnolia tend to merge these small genera into Magnolia s.l. as well. At present, western botanists tend toward a big Magnolia genus, whereas many Chinese botanists still recognize the different small genera.
The bark from M. officinalis has long been used in traditional Chinese medicine, where it is known as hou po (厚朴). In Japan, kōboku, M. obovata has been used in a similar manner. The aromatic bark contains magnolol and honokiol, two polyphenolic compounds that have demonstrated anti-anxiety and anti-angiogenic properties. Magnolia bark also has been shown to reduce allergic and asthmatic reactions.
Magnolia has attracted the interest of the dental research community because magnolia bark extract inhibits many of the bacteria responsible for caries and periodontal disease. In addition, the constituent magnolol interferes with the action of glucosyltransferase, an enzyme needed for the formation of bacterial plaque.