Lythraceae
Template:Short description Template:Automatic taxobox
Lythraceae is a family of flowering plants, including 32 genera, with about 620 species of herbs, shrubs, and trees.<ref name="Stevens 2001">Template:Cite web</ref> The larger genera include Cuphea (275 spp.), Lagerstroemia (56), Nesaea (50), Rotala (45), and Lythrum (35).<ref name="Judd 2008">Template:Cite book</ref> It also includes the members of the former families of the pomegranate (Punica granatum, formerly in Punicaceae) and of the water caltrop (Trapa natans, formerly in Trapaceae). Lythraceae has 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 the flower petals emerge from the rim of the calyx tube. The petals often appear crumpled.
Characteristics
Lythraceae species are most often herbs, and less often shrubs or trees; the shrubs and trees often have flaky bark.<ref name="Mabberley 2008">Template:Cite book</ref> 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.<ref name="Judd 2008" /><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Leaves
The leaves generally have an opposite arrangement, but sometimes are whorled or alternate. They are simple with smooth margins and pinnate venation.<ref name="Judd 2008"/> Stipules are typically reduced, appearing as a row of minute hairs,<ref name="Judd 2008"/> or absent.<ref name="Mabberley 2008"/>
Flowers
The flowers are bisexual, radially or occasionally bilaterally symmetric, with a well-developed hypanthium. The flowers are most commonly quadimerous but can be heximerous, with four to eight 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.<ref name="Judd 2008"/> Usually, twice as many stamens as petals are seen, 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.<ref name="Stevens 2001"/> The ovary is typically superior, infrequently semi-inferior,<ref name="Graham and Cavalcanti">Template:Cite web</ref> or rarely inferior. The two to many carpels can be fused together (syncarpous), with two to numerous ovules in each locule, with axile placentation of the ovules.<ref name="Judd 2008" />
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.<ref name="Judd 2008" />
Fruits and seeds
The fruit is usually a dry, dehiscent capsule, occasionally a berry. The seeds are usually flattened and/or winged, with a multilayered outer integument.<ref name="Judd 2008" /> Epidermal hairs that expand and become mucilaginous when wet are found in about half the genera.<ref name="Stevens 2001" />
Distribution
The Lythraceae are widely distributed, but with most species tropical and some temperate.<ref name="Stevens 2001" /><ref name="Judd 2008" /> They are absent from the Sahara and most arid regions of Australia.<ref name="Stevens 2001" /> Many species occur in aquatic or semi-aquatic habitats (Decodon, Didiplis, Rotala, Sonneratia, Trapa).<ref name="Judd 2008" /><ref name="Mabberley 2008" /> The oldest fossils of the family are pollen from the Late Cretaceous (Campanian) of Wyoming in western North America, around 82 to 81 million years old.<ref>Template:Cite journal</ref>
Economic importance
Edible crops include the pomegranate (Punica granatum) and the water caltrop (Trapa bicornis or T. natans). The pomegranate is cultivated for the fleshy arils surrounding the seeds, and the water caltrop for its seeds. Henna (Lawsonia inermis) is cultivated for the dye of the same name, derived from its leaves.
Ornamentals are grown from a number of genera, including Cuphea, Lagerstroemia (crape myrtles), and Lythrum (loosestrifes).<ref name="Judd 2008" />
Purple loosestrife (Lythrum salicaria) is an invasive exotic weed of wetlands throughout Canada and the United States.<ref>Template:Cite web</ref>
Taxonomy
Within the order Myrtales, the family Lythraceae is most closely related to the Onagraceae, with the Combretaceae sister to both families.<ref name="Judd 2008" /><ref name="Graham and Cavalcanti" /> Molecular phylogeny work has led to the inclusion of the formerly recognized families Duabangaceae, Punicaceae, Sonneratiaceae, and Trapaceae.<ref name="Graham and Cavalcanti" />
Genera
Lythraceae consists of 28 genera<ref name = powo>Template:Cite web</ref> in five subfamilies:
Lythroideae
Authority: de Jussieu ex Walker-Arnott, 1832; previously 'Lythraceae sensu stricto'<ref name="Christenhusz-Byng2016">Template:Cite journal</ref> Template:Div col
- Adenaria Template:Small
- Ammannia Template:Au (synonyms Crenea Template:Small, Hionanthera Template:Small, and Nesaea Template:Small)
- Capuronia Template:Small
- Cuphea Template:Small
- Decodon Template:Small
- Didiplis Template:Small
- Diplusodon Template:Small
- Galpinia Template:Small
- Ginoria Template:Small (synonym Haitia Template:Small)
- Gyrosphragma Template:Small
- Heimia Template:Small
- Koehneria Template:Small
- Lafoensia Template:Small
- Lagerstroemia Template:Small
- Lawsonia Template:Small
- Lourtella Template:Small
- Lythrum Template:Small
- Pehria Template:Small
- Pemphis Template:Small
- Physocalymma Template:Small
- Pleurophora Template:Small
- Rotala Template:Small
- Tetrataxis Template:Small
- Woodfordia Template:Small
- Subfamily Punicoideae (Horan. 1834) S. A. Graham, Thorne & Reveal 1998 = 'Punicaceae',<ref name="Graham 1998">Template:Cite journal</ref> 1 genus:
- Subfamily Sonneratioideae (Engl. & Gilg 1924) S. A. Graham, Thorne & Reveal 1998,<ref name="Graham 1998"/> 1 genus:
- Subfamily Duabangoideae (Takht. 1986) S. A. Graham, Thorne & Reveal 1998 = 'Duabangaceae',<ref name="Graham 1998"/> 1 genus:
- Subfamily Trapoideae Voigt 1845 = 'Trapaceae', 1 genus:
- Subfamily Incertae sedis
- †Shirleya Pigg & DeVore (Miocene, Washington state)<ref name="Pigg2005">Template:Cite journal</ref>
Gallery
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Crepe myrtle flowers - the petals emerge from the calyx tube.
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Rotala species
References
Further reading
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Template:Angiosperm families Template:Taxonbar Template:Authority control