Lythraceae are a family of flowering plants. It includes about 620 species of mostly herbs, with some shrubs and trees, in 31 genera.^[1] Major genera include Cuphea (275 spp.), Lagerstroemia (56), Nesaea (50), Rotala (45), and Lythrum (35).^[2] Lythraceae have a worldwide distribution, with most species in the tropics but ranging into temperate climate regions as well.

The family is named after the type genus, Lythrum, the loosestrifes (e.g. Lythrum salicaria Purple loosestrife) and also includes henna (Lawsonia inermis). It now includes the pomegranate, formerly classed in a separate family Punicaceae. The family also includes the widely cultivated crape myrtle trees. Botanically, the leaves are usually in pairs (opposite), and flowers have petals that emerge from the rim of the calyx tube. The petals often appear crumpled.

Characteristics

The Lythraceae are most often herbs, and less often shrubs or trees; the shrubs and trees often have flaky bark.^[3] Traits shared by species within the Lythraceae that distinguish them from belonging to other plant families are the petals being crumpled in the bud and the many-layered outer integument of the seed.^[2]

Leaves

The leaves generally have an opposite arrangement, but sometimes are whorled or alternate. They are simple with smooth margins and pinnate venation.^[2] Stipules are typically reduced, appearing as a row of minute hairs,^[2] or absent.^[3]

Flowers

The flowers are bisexual, radially or occasionally bilaterally symmetric, with a well-developed hypanthium. The flowers are most commonly 4-merous but can be 6-merous, with 4-8 sepals and petals. The sepals may be distinct, partially fused to form a tube, or touching without overlapping. The petals are crumpled in the bud and wrinkled at maturity, and are typically distinct and overlapping; they are occasionally absent.^[2] There are usually twice as many stamens as petals, arranged in two whorls, and the stamens are often unequal in length. Occasionally the stamens are reduced to one whorl, or are more numerous with multiple whorls.^[1] The ovary is typically superior, infrequently semi-inferior,^[4] or rarely inferior. There can be two to many carpels, which are fused together (syncarpous), and there can be two to numerous ovules in each locule, with axile placentation of the ovules.^[2]

Heterostyly – the presence of two (distylous) or three (tristylous) distinct flower morphs within a species differing in the lengths of the pistil and stamens – is common within the Lythraceae.^[2]

Gallery

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  Crape Myrtle

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  Crape Myrtle flowers - notice how the petals emerge from the calyx tube.

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  Lythrum salicaria

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  Cuphea ignea

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  Cuphea nudicostata

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  Pomegranate

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  Rotala species

Genera

Lythraceae has 31 genera in five subfamilies, as follows:

• Subfamily Lythroideae Juss. ex Arn. 1832 = 'Lythraceae sensu stricto', 27 genera:

• Subfamily Punicoideae (Horan. 1834) S. A. Graham, Thorne & Reveal 1998 = 'Punicaceae',^[5] 1 genus:

• Punica

• Subfamily Sonneratioideae (Engl. & Gilg 1924) S. A. Graham, Thorne & Reveal 1998,^[5] 1 genus:

• Sonneratia

• Subfamily Duabangoideae (Takht. 1986) S. A. Graham, Thorne & Reveal 1998 = 'Duabangaceae',^[5] 1 genus:

• Duabanga

• Subfamily Trapoideae Voigt 1845 = 'Trapaceae', 1 genus:

• Trapa

References

Further reading

Wikimedia Commons has media related to: Lythraceae

Wikispecies has information related to: Lythraceae

• Little S. A., Stockey R. A., and Keating, R. C. (2004). "Duabanga-like leaves from the Middle Eocene Princeton chert and comparative leaf histology of Lythraceae sensu lato". American Journal of Botany 91 (7): 1126–1139. doi:10.3732/ajb.91.7.1126. PMID 21653468. 
• Carr, Gerald. "Lythraceae". University of Hawaii. Archived from the original on 2008-12-05. http://web.archive.org/web/20081205132651/http://www.botany.hawaii.edu/faculty/carr/lythr.htm. Retrieved 2008-12-20. 
• Lythraceae in L.Watson and M.J.Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval.