Rhynchosia tomentosa

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Rhynchosia tomentosa
Rhynchosia tomentosa Gil.jpg
Photo taken by Gil Nelson
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Order: Fabales
Family: Fabaceae ⁄ Leguminosae
Genus: Rhynchosia
Species: R. tomentosa
Binomial name
Rhynchosia tomentosa
(L.) Hook. & Arn.
RHYN TOME dist.jpg
Natural range of Rhynchosia tomentosa from USDA NRCS Plants Database.

Common name: Twining snoutbean (Nelson 2005)

Taxonomic notes

Synonyms: Rhynchosia erecta (Walter) A.P. de Candolle; Rhynchosia intermedia (Torrey & Gray) Small.[1]


Is strongly paraheliotropic.[2]

“Erect, trailing or climbing, perennial herbs or shrubs. Leaves pinnately 3-foliolate or occasionally 1-foliolate; leaflets usually entire and often bearing amber glands, usually estipellate; stipules ovate to lanceolate. Flowers papilionaceous, rarely solitary or in pairs but usually in axillary or occasionally also terminal racemes, several to numerous, loose to compactly clustered, pedicellate, each subtended by a caduceus bract. Calyx tube campanulate or tubular, nearly regular, lobes equal or nearly so in size but with the 2 uppermost partially united; petals yellow in ours, often equaling or even shorter than the calyx; stamens diadelphous, 9 and 1. Legume usually oblong and flattened, 1-2 seeded, dehiscent.”[3]

"Erect herb (1.5) 3-9 m tall with terete to strongly angled, densely pubescent stems. Leaves 3-foliolate; leaflets ovate to oblong or rhombic-ovate, elliptic or obovate, 2-7 cm long, 1/3 to ½ as wide, conspicuously reticulate, moderately to densely short-pubescent, with few to numerous, inconspicuous glands above and velvety tomentose with numerous inconspicuous glands beneath, stipels lacking; stipules soon deciduous, linear-lanceolate, 4-10 mm long. Racemes axillary and terminal, 1.5- cm long, subsessile or on peduncles to 2 cm long with numerous, closely clustered flowers on pedicels 1-3 mm long subtended by linear-subulate to setaceous bract 2-8 mm long. Calyx densely pilose, abundantly but inconspicuously glandular the tube 1.5-2 mm long, lobes linear-subulate4-6 mm long, the upper 2 united for about ½ their length; petals yellow, 5-7 mm long. Legume 1.2-1.6 cm long, 5-7 mm broad, short-pubescent and inconspicuously glandular."[3]


R. tomentosa was found in the study area “within the Upper Coastal Plain Ecoregion with nearly level to gently rolling topography and a maximum elevation of 240m.”[4]



In the Coastal Plains, R. tomentosa can be found in pine-oak woodlands, old growth longleaf pine stands, frequently burned mature longleaf pine-wiregrass stands, longleaf pine sandhills, pine flatwoods, mature longleaf pine savanna, shady oak-hickory woods, hammocks, and calcareous glades.[5][6] It can also occur in recently burned scrubs of cutover pinewoods, former pine plantations, pastures, cut-over cedar glades, roadsides, near pond drains, old fields, powerline clearings, chalk prairies, and clearings of shortleaf pine stands.[5] Soil types include sand, moist loamy soils, sandy loam, and loamy sand.[5]

Associated species include Pinus palustris, Aristida stricta, Magnolia, Quercus, Rhynchosia reniformis and R. difformis.[5]

Rhynchosia tomentosa is an indicator species for the Clayhill Longleaf Woodlands community type as described in Carr et al. (2010)[7]


This species has been observed to flower from May through August[8], and fruits May through October.[5][6]

Fire ecology

Populations of Rhynchosia tomentosa have been known to persist through repeated annual burns.[9][10] This species was observed as an understory plant from frequently burned old-growth mountain longleaf pine stands at Fort McClellan, Alabama.[11]

Conservation, cultivation, and restoration

R. tomentosa was found to be an indicator species in areas 30-80 years after clear-cutting in a southeastern mixed pine forest.[4]

Cultural use

Photo Gallery

References and notes

  1. Weakley, A.S. 2015. Flora of the southern and mid-atlantic states. Working Draf of 21 May 2015. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
  2. KMR observation at Pebble Hill Plantation, Georgia in July.
  3. 3.0 3.1 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. 638. Print.
  4. 4.0 4.1 Archer, J. K., D. L. Miller, et al. 2007. Changes in understory vegetation and soil characteristics following silvicultural activities in a southeastern mixed pine forest. Journal of the Torrey Botanical Society 134: 489-504.
  5. 5.0 5.1 5.2 5.3 5.4 Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: July 2015. Collectors: Loran C. Anderson, T. MacClendon, K. MacClendon, Brenda Herring, Don Herring, R. A. Norris, Rodie White, Richard R. Clinebell II, Robert Kral, Mabel Kral, Roy Komarek, John B. Nelson, A. Anrrich, Elias L Potagas, George R. Cooley, Carroll E. Wood, Jr., Robert K. Godfrey, K. Craddock Burks, Gwynn W. Ramsey, R. S. Mitchell, C. Jackson, Sidney McDaniel, G. Wilder, Roy Komarek, W. C. Coker, C. Ritchie Bell, R. L. Wilbur, James D. Ray, Jr., M. F. Buell, Jean Wooten, S. B. Jones, Carleen Jones, A. B. Seymour, H. R. Reed, A. F. Clewell, M. Morgan. States and Counties: Alabama: Baldwin, Cullman, Elmore, Jefferson, Marengo, Perry. Florida: Calhoun, Citrus, Columbia, Dixie, Gadsden, Hamilton, Jackson, Jefferson, Leon, Liberty, Nassau, Santa Rosa, Suwannee, Wakulla. Georgia: Baker, Grady, Seminole, Thomas, Turner. Mississippii: Clarke, Forrest, Jackson, Lawrence, Pearl River. North Carolina: Richmond, Robeson, Sampson, Wake, Warren. South Carolina: Darlington, Newberry. Compiled by Tall Timbers Research Station and Land Conservancy.
  6. 6.0 6.1 Nelson, Gil. East Gulf Coastal Plain. a Field Guide to the Wildflowers of the East Gulf Coastal Plain, including Southwest Georgia, Northwest Florida, Southern Alabama, Southern Mississippi, and Parts of Southeastern Louisiana. Guilford, CT: Falcon, 2005. 184. Print.
  7. Carr, S.C., K.M. Robertson, and R.K. Peet. 2010. A vegetation classification of fire-dependent pinelands of Florida. Castanea 75:153-189.
  8. 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: 19 MAY 2021
  9. Robertson, K.M. Unpublished data collected from Pebble Hill Fire Plots, Pebble Hill Plantation, Thomasville, Georgia.
  10. Platt, W.J., R. Carter, G. Nelson, W. Baker, S. Hermann, J. Kane, L. Anderson, M. Smith, K. Robertson. 2021. Unpublished species list of Wade Tract old-growth longleaf pine savanna, Thomasville, Georgia.
  11. Varner, J. Morgan, John S. Kush, and Ralph S. Meldhal. 2003. Vegetation of Frequently Burned Old-Growth Longlef Pine (Pinus Palustris Mill.) Savannas on Choccolocco Mountain, Alabama, USA. Natural Areas Journal 23.1: 43-52.