Ditrysinia is a small genus in the spurge family (Euphorbiaceae), placed in the order Malpighiales. It was described by Constantine Samuel Rafinesque in 1825 (published in Neogenyton). The genus is monotypic, containing a single recognized species, Ditrysinia fruticosa, commonly known as the Gulf sebastian-bush. A second name once included in the genus, Ditrysinia sylvatica, has since been transferred to the related genus Stillingia as Stillingia sylvatica.
Ditrysinia fruticosa is native to the southeastern United States, occurring across eastern Texas, Louisiana, southwestern Arkansas, Mississippi, Alabama, northern Florida, Georgia, and the Carolinas. It is a monoecious shrub, typically reaching 1.5 to 2.5 meters in height, with alternately arranged leaves that range from elliptic to lance-elliptic in shape, 3 to 7.5 cm long and 0.8 to 3.5 cm wide.
The species favors shaded, moist-to-wet ground and is classified by the USDA as facultative to facultative-wetland. It is typically found in swampy forests and other damp, shaded settings, including mesic woodlands and floodplain forests, though it has also been recorded on drier limestone bluffs. As a member of Euphorbiaceae, it shares the family's broader characteristics, though detailed floral and fruiting data specific to the genus are limited in general references.
Distribution
Ditrysinia fruticosa, the genus's only species, is native to the southeastern United States — eastern Texas, Louisiana, southwestern Arkansas, Mississippi, Alabama, northern Florida, Georgia, and North and South Carolina.
Ecology
The species grows in mostly shaded, moist-to-wet habitats such as swampy forests, mesic woodlands, and floodplain forests, and is occasionally found on limestone bluffs. The USDA classifies it as facultative to facultative-wetland.
Taxonomy Notes
Ditrysinia was described as a genus in 1825 by Rafinesque and is placed in family Euphorbiaceae, order Malpighiales. It is monotypic, containing only Ditrysinia fruticosa. A name once included in the genus, Ditrysinia sylvatica, has since been reclassified as Stillingia sylvatica.
