Jeffersonia

{{Short description|Genus of flowering plants belonging to the barberry family}} {{Redirect|Twinleaf|the town in the Pokémon franchise|Pokémon regions#Sinnoh{{!}}Pokémon regions}} {{Automatic taxobox | name = Twinleaf | image = Jeffersonia diphylla kz03.jpg | taxon = Jeffersonia | authority = Barton 1793 not Brickell 1800 (syn of ''Gelsemium'' in Loganiaceae) }}

'''''Jeffersonia''''', also known as '''twinleaf''' or '''rheumatism root''', is a small genus of herbaceous perennial plants in the family Berberidaceae. They are uncommon spring wildflowers and grow in limestone soils of rich deciduous forests. ''Jeffersonia'' was named for United States President Thomas Jefferson by his contemporary Benjamin Smith Barton.<ref>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=116785 Flora of North America: Jeffersonia]</ref> This genus was formerly grouped in genus ''Podophyllum''. Twinleaf is protected by state laws as a threatened or endangered plant in Georgia, Iowa, New York, and New Jersey.<ref>[https://plants.usda.gov/java/profile?symbol=JEDI USDA Plants Database: Jeffersonia]</ref>

== Description == ''Jeffersonia diphylla'' has leaves and flowers that are smooth and emerge directly from the rhizome. The leaves are divided into two leaflets which are half-ovate in shape with entire or shallowly toothed margins.<ref name="CoffinPfannmuller1988">{{cite book|author1=Barbara Coffin|author2=Lee Pfannmuller|title=Minnesota's Endangered Flora and Fauna|url=https://books.google.com/books?id=wfWNq91AjeoC|year=1988|publisher=U of Minnesota Press|isbn=978-0-8166-1689-3|page=103}}</ref> It has showy white flowers with four sepals, eight petals, eight stamens, and a singly pistil;<ref name="CoffinPfannmuller1988"/> the flower resembles bloodroot flowers. The short-lived flower appears in April or May before the forest canopy appears (see spring ephemeral). The fruit is a green pear-shaped capsule with a hinged top. The characteristic leaves are large and nearly divided in half, giving rise to its common name, twinleaf. It rarely grows taller than {{convert|12|inch|cm}}. As with other deciduous forest plants, the seeds are dispersed by ants, a process known as myrmecochory.

== Species == ;accepted species<ref name=k>[http://www.theplantlist.org/tpl1.1/search?q=Jeffersonia The Plant List, search for ''Jeffersonia'']</ref> *''Jeffersonia diphylla'' (L.) Pers. – Eastern North America especially Great Lakes region, Ohio Valley, and Appalachians<ref>[http://bonap.net/MapGallery/County/Jeffersonia%20diphylla.png Biota of North America Program 2013 county distribution map]</ref>

;unresolved names<ref name=k/> *''Jeffersonia dubia'' (Maxim.) Benth. & Hook. f. ex Baker & Moore – China, Korea, Russia (called ''Plagiorhegma dubium'' in Flora of China<ref>[http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=242338581 Flora of China Vol. 19 Page 783 <big>鲜黄连</big> xian huang lian ''Plagiorhegma dubium'' Maximowicz]</ref>) *''Jeffersonia lobata'' Nutt. *''Jeffersonia odorata'' Raf.

;species in homonymic genus<ref name=k/> In 1800, Brickell used the name ''Jeffersonia'' to refer to some plants in the Loganiaceae, thus creating an illegitimate homonym.<ref>[http://www.tropicos.org/Name/40033270 Tropicos, ''Jeffersonia'' Brickell ]</ref> Species names coined using this illegitimate use of the name: *''Jeffersonia sempervirens'' Brickell, now called ''Gelsemium sempervirens'' (L.) J.St.-Hil

==Distribution and habitat== ''Jeffersonia diphylla'' is native to Eastern North America where it is found from Minnesota east to New York and south to Tennessee.<ref name="CoffinPfannmuller1988"/> In Minnesota it grows in the lower southeastern section of the state in mesic deciduous forests and most commonly in ravines or on talus slopes.<ref name="CoffinPfannmuller1988"/> In Minnesota it has a preference for growing on calcareous soils of north and east-facing slopes and is listed as a threatened species.<ref name="CoffinPfannmuller1988"/> In Minnesota it is found in association with other uncommon woodland plants such as ''Hydrastis canadensis'' (golden seal) and ''Dicentra canadensis'' (squirrel-corn).<ref name="CoffinPfannmuller1988"/>

== Uses == ''Jeffersonia'' has had a variety of medical uses. One is hinted at by an archaic common name of ''Jeffersonia diphylla'', Rheumatism root. The roots of both species contain berberine, a known anti-tumor alkaloid. The plant is therefore considered poisonous.

right|thumb|250px|A specimen of ''Jeffersonia diphylla'' in bloom.

=== America === Native Americans use ''Jeffersonia diphylla'' for a variety of medicines.

The Cherokee use an infusion of this plant for treating dropsy, as well as gravel and urinary tract problems, and as a poultice for sores and inflammation.<ref>Hamel, Paul B. and Mary U. Chiltoskey 1975 Cherokee Plants and Their Uses – A 400 Year History. Sylva, N.C. Herald Publishing Co. (p. 59)</ref>

The Iroquois used a decoction of the plant to treat gall and diarrhea.<ref>Herrick, James William 1977 Iroquois Medical Botany. State University of New York, Albany, PhD Thesis (p. 332)</ref>

The whole plant was used in early American medicine as an antispasmodic, diuretic, emetic, expectorant and general tonic. The "root" was once also used as an emetic in large doses, and as an expectorant in small doses.<ref>[http://www.pfaf.org/database/plants.php?Jeffersonia+diphylla Plants for a Future Database: ''J. diphylla'']</ref> Modern medicine does not use this plant.

==References== {{Reflist}}

Category:Berberidaceae Category:Berberidaceae genera Category:Monotypic Ranunculales genera Category:Thomas Jefferson Category:Taxa named by Benjamin Smith Barton