Ctenium aromaticum

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Common Names: Toothache Grass; Orange Grass [1]

Ctenium aromaticum
Ctenium aromaticum.JPG
Photo by Kevin Robertson
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta - Flowering plants
Class: Liliopsida - Moncots
Order: Cyperales
Family: Poaceae
Genus: Ctenium
Species: C. aromaticum
Binomial name
Ctenium aromaticum
Natural range of Ctenium aromaticum from USDA NRCS Plants Database.

Taxonomic Notes

Synonym: Campulosus aromaticus (Walter) Trinius.[2]

Variety: none.[2]


C. aromaticum is a perennial graminoid of the Poaceae family native to North America. [1] The whole plant is aromatic, which is what the specific epithet is named after. Sterile individuals can be identified by the broad and bicolored leaves that are bluish on the upper side and bright green on the under side.[3] The plant as a whole reaches heights between 2 and 3 feet, with leaf blades 6 to 10 inches long. Seedhead is a spike that is curved with sessile spikelets on one side of rachis, which gives it the appearance of a comb.[4] Average maximum root depth has been found to be approximately 12 centimeters, and average root porosity was found to be 9.1%.[5]


C. aromaticum can be found in the southeastern part of the United States, specifically in Florida, Georgia, Alabama, Mississippi, Louisiana, South Carolina, North Carolina, and Virginia. [1] It is an endemic species of the Southeastern Coastal Plain[3] longleaf pine forest range.[6]



Ideal habitats for the C. aromaticum are in moist clay that may have some standing water after heavy rains. It has adapted to extremely wet conditions with acidic soils. [1] C. aromaticum is considered an indicator species in the upper Florida Panhandle wetland regions. It is also a dominant grass in lower panhandle savannas. [7] Specimens have been collected from habitats including longleaf pineland, wet loamy sands near bog, recently burned pineland, wiregrass savannas, flatwoods savannas, ponds, and prairies. [8] As well, this species is listed as a facultative wetland species, where it grows mostly in wetlands but can also be found in non-wetland areas.[1] The species has been shown to benefit more from a thinned overstory rather than a clearcut overstory.[9] C. aromaticum decreased in frequency and biomass in response to soil disturbance by clearcutting and chopping in North Florida flatwoods forests. It has shown resistance to regrowth in reestablished native flatwood habitat that was disturbed by clearcutting and chopping.[10]

Associated species: Aristida berichiana, Aristida sp., Serenoa repens, Ilex glabra, Pinguicula sp., Panicum sp., Sporobolus floridanus, Pinus palustris, Sarracenia flava, Eriocaulon sp., Euphorbia inundata, Nolina atopocarpa, Aster reticulatus, Buchnera floridana, Hypericum opacum, Eryngium integrifolium, Xyris elliottii, Habenaria integra, Polgala ramosa, Polygala lutea, Hibiscus aculeatus, Tofieldia racemosa, Oxypolis sp., Rhexia alifanus, Arnoglossum ovatum, and Sabatia difformis.[8]

Ctenium aromaticum is frequent and abundant in the Upper Panhandle Savannas, Lower Panhandle Savannas, and Panhandle Seepage Savannas community types as described in Carr et al. (2010).[11]


C. aromaticum flowers periodically between June and August, but can flower later in response to fires in the late summer.[3] It has been observed to flower April through September as well as November with peak inflorescence in April, July, and September.[12] However, it has been seen to flower earlier in the year, a few months after a prescribed burn. Edwin Bridges observed a region starting to flower in February after a prescribed fire in November in a pine savanna. .[13]

Seed bank and germination

The seeds ripen in May and June that develop into stalks that produce plentiful seeds.[4]

Fire ecology

Seeds are produced after the region has been burned.[1] It is known to only flower generally in response to fire.[3] It is a long-lived species that is indicative of immediate post-fire flowering.[14] C. aromaticum can grow rapidly as soon as 6 weeks in response to fire disturbance.[15]

Herbivory and toxicology

This grass can be used for livestock to graze on.[4] Cattle can forage Ctenium aromanticum in the early spring after burning.[16] The seeds are one of the preferred species by the Henslow's sparrow for food in the winter. This species had long been considered an indicator species of Henslow's sparrow habitats. [17]

Conservation, cultivation, and restoration

For restoration efforts, a study by Glitzenstein outplanted Ctenium aromaticum along with Aristida beyrichiana, Sorghastrum nutans, Agrimonia incise, Parnassia caroliniana, Plantago sparsiflora, and Conradina glabra in order to restore a mesic pine savanna site with success.[18]

Cultural use

The plant if chewed by humans causes numbness to the mouth, tongue, and lips[3] due to an isobutylamide compound present in the rhizome.[19][20][21]

Photo Gallery

References and notes

  1. 1.0 1.1 1.2 1.3 1.4 1.5 USDA Plant Database
  2. 2.0 2.1 Weakley, A.S. 2015. Flora of the southern and mid-atlantic states. Working Draft of 21 May 2015. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
  3. 3.0 3.1 3.2 3.3 3.4 Weakley, A. S. (2015). Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC, University of North Carolina Herbarium.
  4. 4.0 4.1 4.2 Magee, P. (2012). Plant Fact Sheet: Toothache Grass Ctenium aromaticum. N.R.C.S. United States Department of Agriculture. Baton Rouge, LA.
  5. Brewer, J. S., et al. (2011). "Carnivory in plants as a beneficial trait in wetlands." Aquatic Botany 94: 62-70.
  6. Sorrie, B. A. and A. S. Weakley 2001. Coastal Plain valcular plant endemics: Phytogeographic patterns. Castanea 66: 50-82.
  7. Carr, S. C., et al. (2010). "A Vegetation Classification of Fire-Dependent Pinelands of Florida." Castanea 75(2): 153-189.
  8. 8.0 8.1 URL: http://herbarium.bio.fsu.edu. Last accessed: June 2018. Collectors: Loran C. Anderson, Nancy E. Jordan, R.K. Godfrey, John Nelson, G. Knight, R. Wnek, John Morrill, Bruce Hansen, A. Curtiss, A. Clewell, E. Tyson, Steve L. Orzell, Edwin Bridges, Sidney McDaniel, R. Kral, O. Lakela, William Reese, Paul Redfearn, Grady W. Reinert, R.Lazor, J.B. McFarlin, P.Ferral, R. Porcher. States and counties: Florida (Wakulla, Liberty, Bay, Franklin, Nassau, Escambia, Duval, Holmes, Jefferson, Santa Rosa, Pasco, Calhoun, Leon, Osceola, Highlands, Jackson), Georgia (Thomas, Dougherty), South Carolina (Berkely)
  9. Brockway, D. G. and C. E. Lewis (2003). "Influence of deer, cattle grazing and timber harvest on plant species diversity in a longleaf pine bluestem ecosystem." Forest Ecology and Management 175: 49-69.
  10. 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.
  11. Carr, S.C., K.M. Robertson, and R.K. Peet. 2010. A vegetation classification of fire-dependent pinelands of Florida. Castanea 75:153-189.
  12. 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: 22 APR 2019
  13. Observation by Edwin Bridges in Highlands County, Fl., February 12, 2016, posted to Florida Flora and Ecosystematics Facebook Group February 13, 2016.
  14. Hinman, S. E. and J. S. Brewer (2007). "Responses of Two Frequently-Burned Wet Pine Savannas to an Extended Period without Fire." The Journal of the Torrey Botanical Society 134(4): 512-526.
  15. Walker, J. and R. K. Peet (1983). "Composition and species diversity of pine-wiregrass savannas of the Green Swamp, North Carolina." Vegetatio 55: 163-179.
  16. Byrd, Nathan A. (1980). "Forestland Grazing: A Guide For Service Foresters In The South." U.S. Department of Agriculture.
  17. DiMiceli, J. K., et al. (2007). "Seed preferences of wintering Henslow's sparrows." Condor 109: 595-604.
  18. Glitzenstein, J. S., Streng, D. R., Wade, D. D., & Brubaker, J. (2001). Starting new populations of longleaf pine ground-layer plants in the outer coastal plain of South Carolina, USA. Natural Areas Journal, 2, 89–110.
  19. Denhof, Carol. 2016. Plant Toothache Grass Ctenium Aromaticum (Walter) Wood. The Longleaf Leader – Denizens of the Longleaf Woodland. Vol. VIII. Iss. 4. Page 10
  20. Sorries, B.A. 2011. A Field Guide to Wildflowers of the Sandhills Region. The University of North Carolina Press. Chapel Hill, NC. 378pp.
  21. USDA, NRCS. 2015 The PLANTS Database (http://plants.usda.gov, 16 November 2015). National Plant Data Team, Greensboro, NC 27401-4901 USA.