Agalinis tenuifolia

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Agalinis tenuifolia
Agal tenu.jpg
Photo by John R. Gwaltney, Southeastern
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta - Flowering plants
Class: Magnoliopsida - Dicotyledons
Order: Lamiales
Family: Orobanchaceae
Genus: Agalinis
Species: A. tenuifolia
Binomial name
Agalinis tenuifolia
(Vahl) Raf.
AGAL TENU dist.jpg
Natural range of Agalinis tenuifolia from USDA NRCS Plants Database.

Common names: Slender garardia; Slenderleaf false foxglove

Taxonomic notes

Synonyms: Gerardia tenuifolia Vahl; Gerardia polyphylla Small


Annual. Parasitic to the roots of grasses and other herbs. Leaves are opposite, linear to filiform, and sometimes will have tufts on the shoots. Flowers are showy, in terminal racemes; the calyx is 5-parted, the lobes are shorter than the tube; the corolla is 5-parted. The flowers are rose-lavender in color and are rarely white. There are usually 2 yellow lines and numerous purple spots in the throat on the tube. The tube is broad, campanulate, and the lobes are shorter than the tube. The throat is usually lanose at the base of the 2 upper corolla lobes. There are 4 stamens, didynamous, that include filaments and anthers that are also lanose. The stigmas are elongated. The capsules are globose or subglobose, loculicidal.[1]

Is very similar to Agalinis setacea. The difference between Agalinis tenuifolia and Agalinis setacea has to do with the upper corolla lobes. On A. tenuifolia, the upper corolla lobes will be arching over the stamens and closing, or nearly closing, the throat. On a dried specimen of A. tenuifolia, the upper lobes are glabrous basally, making it possible for determination. Flowers August to October,[1] with peak inflorescence in October in northern Florida.[2]


Agalinis tenuifolia is the most widely distributed throughout eastern North America,[3] although varieties leucanthera and polyphylla are limited to the southeaseastern U.S..[4]


This species is a vigorous parasite. It forms haustoria on all 19 commercial species included in Appendix III. No clear host preference was shown, although hardwood species supported more parasitic attachments than pine species [3]. It has been observed to be parasitic on grasses, gray goldenrod, western yarrow, wild strawberry, and tall anemone.[5]


Agalinis tenuifolia can be found in undisturbed grasslands and areas with low soil nutrients in the Great Lakes region.[6] Natural habitat in the Coastal Plain includes open upland woodlands, mixed pine-hardwood stands, mesic wooded edges of limestone glades and open grassy limestone glades, scrubby floodplain woods, borders of wooded mesic hammocks, dry sandy slopes, and calcareous clearings.[7] It occurs on xeric limestone prairies of Illinois, [6] and in moist to dry savannas and bluffs.[8] Prefers semi-shade and sandy soils including sandy loam, sandy clay, and drying or dry loamy sand.[7] In Jackson county, FL, A. tenuifolia was found in clay limestone soils of a sunny upland site.[9]

Agalinis tenuifolia also commonly grows in disturbed sites,[3][10] including clear cut areas and the edges of pine plantations. Large populations may also be found growing at the margins of ditches and in other wet or moist habitats.[3]

Associated species include Aristida, Eupatorium, Juniperus, Schoenus nigricans, Tridens flavus, Agalinis divaricata and others.[7]


In the Coastal Plain it has been observed flowering September through November, and fruiting in October and November.[7]

Seed dispersal

The shiny globoid seed capsule containing many small seeds can be blown by the wind.[11] This species is thought to be dispersed by gravity. [12]


It attracts a wide variety of pollinators, including bees from the Halictid family. They serve as larval food for the common buckeye butterfly (Junonia coenia) caterpillars.[11]

Use by animals

Agalinis species, including this one, host larvae of the common buckeye butterfly (Junonia coenia) in Florida.[13][14]

Diseases and parasites

A. tenuifolia is a hemiparasitic species capable of extracting sugars and proteins from a host, along with surviving without a host by preforming photosynthesis.[15] In the absence of a host, it grows autotropically and can complete its lifecycle without a host. When a host is present, reception of chemical signals enable the parasitic mode causing root elongation to slow and accelerated growth of haustorium. Haustorium are not present unless a host is present.[16]

Conservation and management

Cultivation and restoration

Photo Gallery

References and notes

  1. 1.0 1.1 Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. 1964, 1968. Manual of the Vascular Flora of the Carolinas. The University of North Carolina Press. 960 pp. Print.
  2. Nelson, G. PanFlora: Plant data for the eastern United States with emphasis on the Southeastern Coastal Plains, Florida, and the Florida Panhandle. Accessed: 15 JAN 2015.
  3. 3.0 3.1 3.2 3.3 Musselman, L.J. and W.F. Mann, Jr. 1978. Root parasites of southern forests. General Technical Report SO-20. New Orleans, LA, USDA Forest Service.
  4. USDA NRCS Plants Database accessed 15 JAN 2015.
  5. [[1]]Kansas Wildflowers and Grasses. Accessed: March 22, 2016
  6. 6.0 6.1 Hogg, E.H. and J.K. Morton. 1983. The effects of nesting gulls on the vegetation and soil of islands in the Great Lakes. Canadian Journal of Botany 61:3240-3254.
  7. 7.0 7.1 7.2 7.3 Florida State University Robert K. Godfrey Herbarium Database. URL: Last accessed: June 2014. Collectors: Loran C. Anderson, Wilson Baker, L. Brouillet, J. M. Canne, A. F. Clewell, Angus Gholson, Robert K. Godfrey, R. Karl, S. W. Leonard, and John C. Semple. States and Counties: Florida: Calhoun, Escambia, Gadsden, Jackson, Lafayette, Leon, Levy, Liberty, Walton, Wakulla, and Washington. Georgia: Newton.
  8. Wunderlin, Richard P. and Bruce F. Hansen. Guide to the Vascular Plants of Florida. Second edition. 2003. University Press of Florida: Gainesville/Tallahassee/Tampa/Boca Raton/Pensacola/Orlando/Miami/Jacksonville/Ft. Myers. 547 pp. Print.
  9. Cite error: Invalid <ref> tag; no text was provided for refs named Griffith 2015
  10. Observation by Floyd Griffith in Jackson County, October 20, 2016, posted to Florida Flora and Ecosystematics Facebook Group October 20, 2016.
  11. 11.0 11.1 [[2]]Illinois Wildflowers. Accessed: March 21, 2016
  12. 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.
  13. Observation by Roger Hammer in Silver Springs State Park, Marion County, FL. September 2016, posted to Florida Flora and Ecosystematics Facebook Group August 4, 2017.
  14. Missouri Department of Conservation
  15. Riopel, J. L. and L. J. Musselman (1979). "Experimental Initiation of Haustoria in Agalinis purpurea (Scrophulariaceae)." American Journal of Botany 66(5): 570-575.
  16. Wm. Vance, B. and J. L. Riopel (1984). "Experimental Studies of Haustorium Initiation and Early Development in Agalinis purpurea (L.) Raf. (Scrophulariaceae)." American Journal of Botany 71(6): 803-814.