Definitions

appressed

Magnoliaceae

The Magnoliaceae is a family in the flowering plant Order Magnoliales. It consists of two subfamilies:

  • Magnolioideae, of which Magnolia is the most well-known genus.
  • Liriodendroidae, a monogeneric subfamily, of which Liriodendron (Tulip trees) is the only genus.

Unlike most angiosperms, whose flower parts are in rings, the Magnoliaceae have their stamens and pistils in spirals on a conical receptacle. This arrangement is found in old fossil plants and is believed to be primitive for angiosperms. Their flowers are also not so clearly differentiated into having sepals and petals like most other flowering plants; the "dual-purpose" parts that occupy both positions are known as tepals.

The family has approximately 225 species in 7 genera, although some classification systems include all of subfamily Magnoioideae in genus Magnolia. The family ranges across eastern North America, Mexico and Central America, the West Indies, tropical South America, southern and eastern India, Sri Lanka, Indochina, Malesia, China, Japan, and Korea.

Description

The monophyly of Magnoliaceae is supported by a number of shared morphological characters. Flowers are bisexual (with the exception of Kmeria and some species of Magnolia section Gynopodium), radial, and with an elongate receptacle. Leaves are alternate, simple, and sometimes lobed. The inflorescence is a solitary flower with indistinguishable petals and sepals. Sepals range from six to many; stamens are numerous and feature short Filaments which are poorly differentiated from the anthers. Carpels are usually numerous, distinct, and on an elongate recepticle. The fruit is an aggregate of follicles which usually become closely appressed as they mature and open along the abaxial surface. Seeds have a fleshy coat and color that ranges from red to orange (except Liriodendron). Magnoliaceae flowers are showy and beetle pollinated, except for Liriodendron, which is bee pollinated. The carpals of Magnolia flowers are especially thick to avoid damage by beetles who feast and crawl on them. The seeds of Magnolioideae are bird dispersed while the seeds of Liriodendron are wind dispersed.

Biogeography

Due to its great age, Magnoliaceae has become highly scattered in its distribution as a result of major geologic events such as ice ages, continental drift, and mountain formation. This distribution pattern has isolated some species while keeping others in close contact. Extant species of Magnoliaceae are widely distributed in temperate and tropical Asia from the Himalayas to Japan and southwest through Malaysia and New Guinea. Asia is home to approximately two thirds of the species in Magnoliaceae, with the remainder of the family spread across the Americas with temperate species extending into the southern United States and tropical elements extending into Brazil and the West Indies.

Systematics

Due to this great deal of family wide morphological similarity, no consensus has yet emerged on the number of genera in the family. The development of DNA sequencing at the end of the twentieth century had a profound impact on the research of phylogenetic relationships within the family. The employment of ndhF and cpDNA sequences has refuted many of the traditionally accepted phylogenetic relationships within Magnoliaceae. For example, it has shown the genera Magnolia and Michelia to be paraphyletic when the remaining four genera of Magnolioideae are split out. In fact, even many of the subgenera (Magnolia Magnolia, Magnolia Talauma) have been found to be paraphyletic. Although no completely resolved phylogeny– for the family has yet been determined, these technological advances have allowed systematists to broadly circumscribe major lineages, word.

Economic Significance

As a whole, Magnoliaceae is not an economically significant family. With the exception of a great deal of ornamental cultivation, the economic significance of Magnolias is generally confined to the use of wood from certain timber species and the use of bark and flowers from several species believed to possess medicinal qualities. Magnolias have a rich cultural tradition in China where references to their healing qualities go back thousands of years. The Chinese have long used the bark of Magnolia officinalis, a magnolia native to the mountains of China with large leaves and fragrant white flowers, as a remedy for cramps, abdominal pain, nausea, diarrhea, and indigestion. Certain magnolia flowers, such as the buds of Magnolia liliflora, have been used to treat chronic respiratory infections, sinus infections, and lung congestion. Recently, magnolia bark has become incorporated into alternative medicine in the west where tablets made from the bark of M. officinalis have been marketed as an aid for anxiety, allergies, asthma, and weight-loss. Preliminary studies have suggested that compounds found in magnolia bark might have antibacterial and antifungal properties. To this day, however, there has never been a large scale study on the health effects of magnolia bark or flowers.

References

  • Hunt, D. (ed). 1998. Magnolias and their allies. International Dendrology Society & Magnolia Society. ISBN 0-9517234-8-0
  • Azuma, H., García-Franco, J. G., Rico-Gray, V., and Thien, L. B. (2001). Molecular phylogeny of the Magnoliaceae: the biogeography of tropical and temperate disjunctions. American Journal of Botany. 88: 2275-2285.

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