|Photo taken by Gil|
|Division:||Magnoliophyta - Flowering plants|
|Class:||Magnoliopsida – Dicotyledons|
|Natural range of Diodia virginiana from USDA NRCS Plants Database.|
Common name: Virginia buttonweed, large buttonweed
Varieties: Diodia hirsuta Pursh; D. tetragona Walter; D. virginiana var. attenuata Fernald; D. virginiana var. latifolia Torrey & Gray; D. virginiana var. virginiana
Diodia virginiana tends to grow in spreading mats, sometimes floating in shallow water.
Generally, for Diodia genus, they are "annual or perennial herbs. Leaves sessile, opposite pubescent or glabrate, margins hyaline, setose-serrate; stipules linear or fimbriate, ½ as long, or longer than, the fruit. Flowers 4-merous, axillary, usually solitary, sessile; calyx lobes equal or unequal; corolla salverform. Fruit leathery, surmounted by the persistent calyx lobes, splitting into 2, indehiscent, 1-seeded segments." 
Specifically, for D. virginiana species, they are "erect or spreading, usually pubescent perennial from a woody root crown, the stems branched, 1-6 dm or more long. Leaves elliptic-lanceolate to oblanecolate, mostly 2-7 cm long, 4-12 mm wide. Calyx lobes 2, linear-lanceolate, 2-4 mm long, pubescent; corolla white, tube filiform, 7-9 mm long, lobes 3-4 mm long, the inner surface pubescent; stigmas filiform or the style appearing cleft. Fruit pubescent, oblong-ellipsoid, 5-9 mm long, 3-5 mm in diam., prominently ridged. Fruit splitting into 2, indehiscent, 1-seeded segments." 
D. virginiana is native to eastern and central United States, from Connecticut, Pennsylvania, Illinois, and Kansas south to Florida and Texas.
Typical habitats of this species include wet fields, ditches, and other wet to moist habitats. D. virginiana occurs in moist to wet areas, and areas subject to periodic inundation like ephemeral ponds. It occurs in a wide range of light levels, from deep shade to full sun, but tends to prefer sandy soil types such as loamy sand, sand, sandy loam and sandy peat. It can be found in natural communities including pine savannas, grassy areas near lakes and ponds, prairies, floodplain forests, sand bars, cypress-hardwood swamps, swampy woodlands, wetland areas, and calcareous hammocks. However, it can also appear in disturbed habitat, like cutover pine woods, roadsides, old fields, and mowed areas. As well, D. virginiana is a characteristic species of calcareous savannas, and an indicator species of upper panhandle savannas in Florida.
The plant was found to increase its frequency and biomass in response to soil disturbance by clearcutting and chopping in North Florida flatwoods forests. It has shown positive regrowth in reestablished native flatwood habitats that were disturbed by these practices.
Associated species include Diodia teres, Aristida stricta, Polygonum, Sabatia dodecandra, Hypericum galioides, Eupatorium semiserratum.
Diodia virginiana is frequent and abundant in the Calcareous Savannas community type and is an indicator species for the Upper Panhandle Savannas community type as described in Carr et al. (2010).
This species is thought to be dispersed by gravity. 
Seed bank and germination
Tilling and burning cause increase in cover percentage. 
Herbivory and toxicology
This species consists of approximately 5-10% of the diet for large mammals and various terrestrial birds. However, it is considered to have a poor foraging value. Plants in the genus Diodia were recorded in the scat of gopher tortoises (Gopherus polyphemus).
Conservation, cultivation, and restoration
D. virginiana is listed as threatened by the Indiana Department of Natural Resources, Division of Nature Preserves, and listed as endangered by the New Jersey Department of Environmental Protection, Office of Natural Lands Management. It is also considered to be weedy or invasive in some areas of the northeast and the southeast.
References and notes
- Weakley, A.S. 2020. Flora of the Southeastern United States. Edition of 20 October 2020. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
- Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: June 2014. Collectors: Loran C. Anderson, R. K. Godfrey, R. Komarek, R. Kral, Sidney McDaniel, R. A. Norris, A.E. Radford, Cecil R. Slaughter, B. K. Holst, Valerie Renard, Lovette E. Williams, Rev. Robert Brinker, Robert L. Lazor, Grady W. Reinert, Suellen Folensbee, Paul L. Redfearn, Jr., S. W. Leonard, Gary R. Knight, Jame Amoroso, W. G. D'Arcy, Gywnn W. Ramsey, H. Larry Stripling, W. P. Adams, K. Craddock Burks, William Lindsey, D. W. Mather, Jean W. Wooten, Robert J. Lemaire, O. Lakela, Robert J. Lemaire, Leon Neel, R. F. Doren, A. Gholson Jr., K. Willis, R. Cherry, and Annie Schmidt. States and Counties: Florida: Alachua, Bay, Calhoun, Charlotte, Citrus, Collier, Columbia, Dade, Dixie, Duval, Escambia, Flagler, Franklin, Hamilton, Highland, Holmes, Indian River, Jackson, Jefferson, Lake, Leon, Levy, Liberty, Madison, Marion, Okaloosa, Orange, Osceola, Palm Beach, Polk, Osceola, Sarasota, Santa Rosa, St. Johns, Sumter, Taylor, Wakulla, Walton, and Washington. Georgia: Grady and Thomas.
- Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. Manual of the Vascular Flora of the Carolinas. 1964, 1968. The University of North Carolina Press. 979. Print.
- Carr, S. C., et al. (2010). "A Vegetation Classification of Fire-Dependent Pinelands of Florida." Castanea 75(2): 153-189.
- Moore, W.H., B.F. Swindel, and W.S. Terry. (1982). Vegetative Response to Clearcutting and Chopping in a North Florida Flatwoods Forest. Journal of Range Management 35(2):214-218.
- Carr, S.C., K.M. Robertson, and R.K. Peet. 2010. A vegetation classification of fire-dependent pinelands of Florida. Castanea 75:153-189.
- Nelson, G. PanFlora: Plant data for the eastern United States with emphasis on the Southeastern Coastal Plains, Florida, and the Florida Panhandle. www.gilnelson.com/PanFlora/ Accessed: 8 DEC 2016
- Kirkman, L. Katherine. Unpublished database of seed dispersal mode of plants found in Coastal Plain longleaf pine-grasslands of the Jones Ecological Research Center, Georgia.
- Kirkman, L. K. and R. R. Sharitz (1994). "Vegetation disturbance and maintenance of diversity in intermittently flooded Carolina bays in South Carolina." Ecological Applications 4: 177-188.
- Glitzenstein, J. S., D. R. Streng, et al. (2003). "Fire frequency effects on longleaf pine (Pinus palustris, P.Miller) vegetation in South Carolina and northeast Florida, USA." Natural Areas Journal 23: 22-37.
- Moore, W. H., et al. (1982). "Vegetative response to prescribed fire in a north Florida flatwoods forest." Journal of Range Management 35: 386-389.
- Miller, J.H., and K.V. Miller. 1999. Forest plants of the southeast and their wildlife uses. Southern Weed Science Society.
- Hilman, J. B. (1964). "Plants of the Caloosa Experimental Range " U.S. Forest Service Research Paper SE-12
- Birkhead, R. D., et al. (2005). "Patterns of folivory and seed ingestion by gopher tortoises (Gopherus polyphemus) in a southeastern pine savanna." American Midland Naturalist 154: 143-151.
- USDA, NRCS. (2016). The PLANTS Database (http://plants.usda.gov, 2 May 2019). National Plant Data Team, Greensboro, NC 27401-4901 USA.