|Photo by John R. Gwaltney, Southeastern Flora.com|
|Division:||Magnoliophyta - Flowering plants|
|Class:||Magnoliopsida – Dicotyledons|
|Family:||Fabaceae ⁄ Leguminosae|
| Chamaecrista nictitans|
|Natural range of Chamaecrista nictitans from USDA NRCS Plants Database.|
Common name: Sensitive partridge pea
Synonyms: Cassia nictitans var. nictitans; C. nictitans var. hebecarpa Fernald; Chamaecrista nictitans ssp. nictitans var. nictitans; Chamaecrista procumbens (Linnaeus) Greene; Chamaecrista multipinnata Pollard
Varieties: Chamaecrista nictitans (Linnaeus) Moench var. aspera (Muhlenberg ex Elliott) Irwin & Barneby
Chamaecrista nictitans is a decumbent herb that forms large mats.
Generally, in the group Chameacrista it includes trees, shrubs, or herbs. The leaves are evenly 1-pinnate with conspicuous gland(s) on the petiole or rachis. The flowers are either solitary or clustered in axillary racemes or terminal panicles, perfect. The calyx has an inconspicuous tube, 5 lobed, equally imbricate, and often unequal. There are 5 petals and are a little unequal. The stamens 5-10, are often unequal and some are sterile or imperfect. The anthers are basifixed and opening by 2 apical pores. The legume is few-to many-seeded, often septate, and exceedingly variable. Including Chamaecrista Moench, Ditremexa Raf., Emelista Raf. 
Specifically, for Chamaecrista nictitans, the species is an annual, growing up to 1-5 dm tall from the taproot. The stems are glabrous to densley appressed-puberulent with incurved trichomes. The leaves are sensitive with a slender-stalked umbrella-shaped gland, about 0.4-0.8 mm in diameter. Just below the leaves are persistent, striate. The flowers are axillary, solitary, or 2-3 borne in a short raceme. The pedicels grow up to 1-4 mm long. The sepals are lanceolate, growing 3-4 mm long, acuminate. The petals are bright yellow in color, are very unequal, and the lowermost and largest is 6-8 mm long and about 2 times as large as the other four. There are 5 stamens, unequal. The legume is elastically dehiscent, growing 2-4 cm long, and 3-6 mm broad, and is glabrous to most commonly densely appressed-puberulent or rarely villous. 
It is a legume. By mid-season in June and July, a maximum nitrogen-fixing rate was observed.
C. nictitans is tolerant of overstory canopies that decrease the light level to about half the ambient (i.e., it can live in partially shaded areas and its nitrogen-fixing capability won't be significantly affected). It is also tolerant of a wide range of dry to wet soil types, having been found in soils as diverse as sandy silt loam, low black sandy peat, shallow soil overlaying limerock, shell sand, red clay, loessial soil, sandy clay loam, dry marl, calcareous and shaly soils, clay, igneous intrusive rocky soils, and novaculite ridges.
C. nictitans occurs in a variety of natural and disturbed communities. It is found in longleaf pine-wiregrass communities, longleaf pine-scrub oak sandy ridges, annually burned savannas, xeric oak-saw palmetto scrub communities, wooded banks of creeks, slash pine flats, borders of brackish and salt marshes, low weedy swales, laurel oak woodlands, upland slopes, dry sandhills, margins of hillside bogs, and loblolly pine forests. C. nictitans is also able to colonize some disturbed areas, including roadsides, railways, clear-cut pine flatwoods, vacant lots, cultivated fields, power line corridors, old fields, and plantations of young slash pine.
Associated species include Chamaecrista fasciculata, Panicum, Andropogon, Strophostyles leiosperma, oaks, saw palmetto, broomsede, laurel oak, and others.
It has been observed flowering in August through October, and fruiting in August through November.
This species is thought to be dispersed by consumption by vertebrates. 
This species occurs in areas that regularly burn, suggesting a level of fire tolerance.
The following Hymenoptera families and species were observed visiting flowers of Chamaecrista nictitans at Archbold Biological Station:
Halictidae: Augochloropsis sumptuosa
Use by animals
A bee, Augochloropsis anonyma (Cockerell) was found on C. nictitans.
Conservation and management
Cultivation and restoration
References and notes
- 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. 577-8. Print.
- Cathey, S. E., L. R. Boring, et al. (2010). "Assessment of N2 fixation capability of native legumes from the longleaf pine-wiregrass ecosystem." Environmental and Experimental Botany 67: 444-450.
- Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: June 2014. Collectors: Robert K. Godfrey, R. Komarek, R. F. Doren, Cecil R Slaughter, R. Kral, P. O. Schallert, S. M. Tracy, D. B. Ward, D. Burch, J. K. Small, Chas. A. Mosier, Richard D. Houk, A. H. Curtiss, O. Lakela, J. K. Small, G. K. Small, George R. Cooley, Richard J. Eaton, James D. Ray, Jr., C. Ritchie Bell, Loran C. Anderson, Neal Morar, Delzie Demaree, J. J. Rudloe, C.M. Rogers, J. Beckner, J. Carmichael, James R. Burkhalter, Robert L. Lazor, Sidney McDaniel, John Morrill, P. Gillespie, Richard S. Mitchell, W. D. Reese, Joseph Ewan, H. R. Reed, W. R. Anderson, M.N. Sears; Windler, Keenan, - Lombardo, - Williams; R. L. Lane, JR., J. B. Lewis, C. F. Hyams, S. B. Jones, Samuel B. Jones, Jr., John W. Thieret, William B. Fox, Louis Williams, R. L. Wilbur, Edward S. Steele, Robert F. Thorne, Geo M. Merrill, J.B. Norton, Harry E. Ahles, and R.S. Leisner. States and Counties: Alabama: Dale and Sumter. Arkansas: Conway, Garland, Hot Spring, Jefferson, Lee, Pope, Pulaski, and Sebastian. Dist of Columbia: Addison Hts. Florida: Alachua, Baker, Bay, Brevard, Calhoun, Collier, Dade, Dixie, Duval, Escambia, Franklin, Gadsden, Gulf, Hamilton, Hillsborough, Jackson, Jefferson, Lee, Leon, Levy, Liberty, Manatee, Marion, Monroe, Nassau, Okaloosa, Orange, Osceola, Pinellas, Polk, Putnam, St Johns, Sarasota, Seminole, Taylor, Volusia, Wakulla, Walton, and Washington. Georgia: Decatur, Grady, Taylor, and Thomas. Louisiana: Evangeline, Iberia, and Ouachita. Maryland: Baltimore. Mississippi: Harrison, Lamar, Pearl River, and Saratoga-city. North Carolina: Alleghany, Bertie, Bladen, Buncombe, Burke, Caldwell, Carteret, Catawba, Cherokee, Davidson, Harnett, Haywood, Iredell, Jackson, Mitchell, Orange, Robeson, Swain, Vance, Wilkes, and Wilson. South Carolina: Beaufort, Cherokee, Colleton, Darlington, and Jasper. Tennessee: Anderson, Bedford, and Coffee. Virginia: Amelia, Brunswick, Giles, Prince Edward, Roanoke, and Southampton. West Virginia: Cabell.
- 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.
- Deyrup, M.A. 2015. Database of observations of Hymenoptera visitations to flowers of plants on Archbold Biological Station, Florida, USA.
- Deyrup, M. J. E., and Beth Norden (2002). "The diversity and floral hosts of bees at the Archbold Biological Station, Florida (Hymenoptera: Apoidea)." Insecta mundi 16(1-3).