Charles Norman Horn

(b. 1956)

The University of North Carolina at Chapel Hill Herbarium (NCU) curates over 300 vascular plant specimens collected by Charles N. Horn.  As we continue to catalog our holdings, and to accession newly mounted material, without doubt more specimens collected by Dr. Horn will be found.

While Newberry College Herbarium is Horn’s primary repository, his specimens can be found in many herbaria across North America including Austin Peay State University (APSC), Botanical Research Institute of Texas (BRIT; NLU), Butler University (BUT), Carnegie Museum of Natural History (CM), Clemson University (CLEMS), East Kentucky University (EKY), Field Museum (F), Florida Department of Agriculture and Consumer Services (PIHG), Francis Marion University (FMUH), George Mason University (GMUH),  Georgia Southern University (GAS), Harvard Herbaria (GH),   Illinois Natural History Survey (ILLS), Utah State University (USU:UTC), Louisiana State University (LSU), James F. Matthews Center for Biodiversity Studies (UNCC), Miami University (MU), Mississippi Museum of Natural Sciences (MMNS), Missouri Botanical Garden (MO), New York Botanical Garden (NY), North Carolina State University (NCSC), Rutgers University (CHRB), Texas A& M (TAES), Troy University (TROY), University of Alabama (UNA), University of California, Riverside (UCR), Florida Museum of Natural History (FLAS), University of Kansas (KANU),  University of Michigan (MICH), University of South Carolina, Columbia (USCH), University of South Florida (USF), University of Tennessee (TENN), University of Vermont (VT), Valdosta State University (VSC), West Virginia University (WVA), College of William & Mary (WILLI), and Eastern Illinois University (EIU).

Charles Horn grew up in Fairfax, Virginia and earned a B. S. in Biology from George Mason University in 1978.  He earned a M.S. in Environmental Biology from The Ohio State University  in Columbus, Ohio in 1980; the title of his thesis was “Life History of Heteranthera dubia (Jacq.) MacM. (Pontederiaceae) with respect to seasonal and environmental effects on morphology”.  For his doctoral work, Horn continued to study Heteranthera at the University of Alabama in Tuscaloosa; the title to his 1985 doctoral thesis was “A Systematic Revision of the genus Heteranthera (sensu lato; Pontederiaceae)”.

He joined the faculty of Newberry College in Newberry, South Carolina in 1986, and is the Curator of the Newberry College Herbarium (NBYC).

Dr. Charles N. Horn with May-white Azalea (Rhododendron eastmanii). May, 2021.



Horn, Charles N. 1981. An ecological life history of Heteranthera dubia (Jacq.) MacM. (Pontederiaceae) with respect to seasonal and environmental effects on morphology. CLEAR Technical Report no. 214. 104 pp. (published Master’s thesis, The Ohio State University, Columbus).

Horn, Charles N. 1983. The annual cycle of growth in Heteranthera dubia (Pontederiaceae) in Ohio. Michigan Botanist 23: 29-34.

Horn, Charles N. 1986. Typifications and a new combination in Heteranthera (Pontederiaceae). Phytologia 59: 290.

Forest, Herman S., Charles N. Horn, and Bernard A. Marcus. 1986. New observations on galls on Zosterella dubia (Jacq.) Small [Heteranthera dubia (Jacq.) MacM.] infected by Membranosorus heterantherae Ostenfeld & Peterson. Environmental and Experimental Botany 26: 377-384.

Horn, Charles N. 1987. [Family] 205. Pontederiaceae. Flora of Ecuador 29: 1-20.

Horn, Charles N. and Robert R. Haynes. 1987. Typification of Pontederia and its Linnaean species names (Pontederiaceae). Taxon 36: 621-625.

Horn, Charles N. 1987. Pontederiaceae. Flora del Paraguay. [7]: 1-28.

Horn, Charles N. 1988. Developmental heterophylly in the genus Heteranthera (Pontederiaceae). Aquatic Botany 31: 197-209.

Horn, Charles N. 1994. 197. Pontederiaceae. Flora of the Guianas. Series A: Phamerogams, 15: 91-102.

Horn, Charles N. 1997. An Ecological study of Frasera caroliniensis in South Carolina. Castanea 62(3): 185-193.

Hill, Steven and Charles N. Horn. 1997. Additions to the Flora of South Carolina. Castanea 62(3): 194-208.

Horn, Charles N. 1998. Pontederiaceae, pickerel weed family. Journal of the Arizona-Nevada Academy of Science 30 (2): 133-136.

Ward, Andrea B. and Charles N. Horn. 1998. An ecological survey of Dirca palustris L. (Leatherwood) in the piedmont of South Carolina. Castanea 63(2): 165-173.

Horn, Charles N. 1998. A note on Eichhornia paniculata (Spreng.) Solms and Eichhornia meyeri A. G. Schulz (Pontederiaceae) in Paraguay. Candollea 53: 127-130.

Horn, Charles N. 1998. Addenda al tratamiento del género Eichhornia Kunth (Pontederiaceae) de la Flora del Paraguay. Candollea 53: 130-131.

Horn, Charles N. 2005. Distribution and ecological preference of Rhododendron eastmanii Kron & Creel (May-white Azalea) in South Carolina. Castanea 70(1): 1-12.

Horn, Charles N. 2008. A vascular flora of Lynch’s Woods Park, Newberry County, South Carolina. Castanea 73(2): 111-122.

Horn, Charles N. 2011. Heterophylly of Didiplis diandra (Nutt. Ex A. DC.) Wood (Lythraceae) and a key to some rooted shallow water and shoreline herbs of the mid-Atlantic piedmont. Castanea 76(3) 272-278.

Horn, Charles. 2012. The Southern Appalachian Botanical Society: Seventy-five years and growing. Castanea 77(4): 283-302.

Horn, Charles. 2015. A New Hybrid of Asimina (Annonaceae) Based on Morphological and Ecological Data. Castanea 80(4): 260-272.

Pellegrini, Marco and Charles Horn. 2017. Two peculiar new species of Heteranthera Ruiz & Pavon (Pontederiaceae) from Brazil, with notes on inflorescences architecture in the family. PhytoKeys 82: 35-56.

Pellegrini, Marco O. O., Charles N. Horn, and Rafael F. Almeida. 2018. Total evidence phylogeny of Pontederiaceae (Commelinales) sheds light on the necessity of its recircumscription and synopsis of Pontederia L. PhytoKeys 108: 25-83.

Horn, Charles N. 2019. Taxonomy, ecology and distribution of the genus Rhododendron (Ericaceae) in South Carolina. Castanea 84(1): 33-44.

Horn, Charles. 2020. Two new species of Heteranthera (Pontederiaceae) in North America. J. Bot. Res. Texas 14(1): 1-8.

Thompson, Megan L., Zack E. Murrell, Charles N. Horn, Kathleen A. Kron, and Emily L. Gillespie. 2020. Novel microsatellite markers for evaluation of genetic diversity in the teatraploid flame azalea, Rhododendron calendulaceum (Ericaceae). Molecular Biology Reports doi: 10.1007/s11033-020-05813-9.


Kaul, Robert B. and Charles N. Horn. 1986. [Family] 154. Pontederiaceae. pp. 1239-1241. In: Great Plains Association. Flora of the Great Plains. University of Kansas Press, Lawrence. 1392 pp.

Horn, Charles N. 1992. Botanical Survey results on the Greenville Water System Properties, pp. 56-61. In: Greenville Watersheds Study Committee. Properties of the Table Rock and Poinsett Reservoirs, Their Future. Published by the authors.

Horn, Charles N. 1993. Cemetery Demography. pp. 155-170. In: Beiswenger, Jane (Ed.). Experiments to Teach Ecology. Ecological Society of America. [paper developed in cooperation with Nancy Flood].

Horn, Charles N. 1996. A Closer Look: Economic Importance of Plants, pp. 598-599. In: Mader, Sylvia. Biology, 5th Edition. Wm. C. Brown, Publisher.

Horn, Charles N. 1997. Pontederiaceae, p. 178. In: Boggan, J., V. Funk, C. Kelloff, M. Hoff, G. Cremers & C. Feuillet (eds). Checklist of the Plants of the Guianas (Guyana, Surinam, French Guiana), 2nd Edition. Smithsonian Institution, Washington, DC.

Horn, Charles N. 1998. Pontederiaceae, pp. 245-246. In: Dubs, Balthasar. Prodromus Florae Matogrossensis, Part I. Checklist of Angiosperms. The Botany of the Mato Grosso, Series B. 3: 1-444.

Guofamg, Wu and Charles N. Horn. 2000. Pontederiaceae (yu jiu hua ke), pp. 40-42. In: Zhengyi, Wu and Peter H. Raven (co-chairs of editorial committee). Flora of China. 24: 1-430.

Horn, Charles N. and Robert R. Haynes. 2001. Pontederiaceae, pp. 2177-2180. In: Stevens, W. D. , Carmen Ulloa Ulloa, Amy Pool y Olga Martha Montiel (editors). Flora de Nicaragua, Angiospermas (Pandaceae-Zygophyllaceae). Monographs in Systematic Botany 85(3): 1911-2666.

Horn, Charles N. 2002. Pontederiaceae, Pickerel-weed Family. pp. 37-46. In: Flora of North America Editorial Committee. (editors). Flora of North America, Volume 26. Oxford University Press.

Horn, Charles N. 2004. Pontederiaceae, pp. 371-376. In: Steyermark, J. A., Paul E. Berry, Kay Yatskievych, and Bruce Holst (general editors). Flora of the Venezuelan Guyana Volume 8: Poaceae-Rubiaceae.

Horn, Charles N. and Elizabeth McClintock. 2011. Pontederiaceae, pp. 1498-1499. In: Bruce G. Baldwin (Convening Editor) The Jepson Manual, Vascular Plants of California, 2nd edition. University of California Press,