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Lab of Dr. Paula Williamson


Dr. Paula Williamson
Paula S. Williamson, Ph.D.



Phone: 512-245-3312

Fax: 512-245-8713


Biology Department
Texas State University - San Marcos
601 University Drive
San Marcos, TX 78666



Ph.D.  1988    University of California, Santa Barbara 
M.A. 1985    University of California, Santa Barbara 
B.S. 1981    Southwest Texas State University



Professional Experience

Texas State University-San Marcos




Associate Dean of the Graduate College


Associate Chair for Graduate Programs


Associate Professor


Assistant Professor


 University of California at Santa Barbara, Dept. of Biological Sciences                                 




Post-Graduate Assistant



Research Interests

Paula Williamson and Gena Janssen studying a population
of Abronia macrocarpa, an endangered Texas endemic.

  • Conservation Biology/Endangered Species Biology
    My lab is interested in understanding causes of species rareness, particularly with regard to reproductive biology. Our work includes relating life history traits and pollination ecology to genetic variability of rare species. We are also interested in reintroduction as a potential recovery measure.


Courses Currently Taught

BIO 3406: Economic Botany 
BIO 1421: Modern Biology


Research Publications

  • Echo-Hawk, P.D., F.M. Oxley, P.S. Williamson, V. Cantu and K. Ostrand.  2014.  Integrated management of an invasive macrophyte.  Journal of Aquatic Plant Management.  52: 97-101.
  • Ferrazzano, S.* and P.S. Williamson.  2013.  Benefits of mycorrhizal inoculation in reintroduction of endangered plant species under drought conditions.  Journal of Arid Environments.  98: 123-125.
  • Ferguson, A.W., R.E. Strauss, A.W. Strong*, S.J. Birnbaum*, J.M. Poole, G.K. Janssen*,and P.S. Williamson.  2013.  Assessing regional differences in predation of endangered species:  Implications from Texas populations of the endangered star cactus (Astrophytum asterias).  Journal of Arid Environments.  97: 143-149.
  • Goodson, J.J.* and P.S. Williamson.  2011.  Germination of seeds in the endangered Abronia macrocarpa.  Southwestern Naturalist  56: 141-146.
  • Birnbaum, S.J.*, J.M. Poole, and P.S. Williamson.  2011.  Reintroduction of star cactus Astrophytum asterias by seed sowing and seedling transplanting, Las Estrellas Preserve, Texas, USA.  Conservation Evidence  8: 43-52.
  • Blair, A.W.* and P.S. Williamson.  2010.  Pollen dispersal in star cactus (Astrophytum asterias).  Journal of Arid Environments  74: 525-527.
  • Ferguson, A.W. and P.S. Williamson.  2009.  New Host Plant Record, the Endangered Star Cactus (Astrophytum asterias), for Moneilema armatum LeConte (Coleoptera: Cerambycidae: Lamiinae).  The Coleopterists Bulletin.  63: 218-220.
  • Watson, C.A., F.W. Weckerly, J.S. Hatfield, C. Farquhar, and P.S. Williamson. Detection, occupancy and survey effort of Golden-cheeked warblers (Dendroica chrysoparia). Animal Conservation. Accepted pending revision.
  • Blair, A. and P.S. Williamson. Pollinator effectiveness and importance in star cactus (Astrophytum asterias). Southwestern Naturalist. In press.
  • Atkins, E.O. and P.S. Williamson. 2008. Comparison of four techniques to eradicate elephant ear. Journal of Aquatic Plant Management. In press.
  • Strong, A.W. and P.S. Williamson. 2007. Breeding system of Astrophytum asterias. Southwestern Naturalist 52: 341-346.
  • Williamson, P.S. 2004. Status of the Large-fruited sand verbena (Abronia macrocarpa). Proceedings of the Texas Plant Conservation Conference. Lady Bird Johnson Wildflower Center Publication.
  • Schneider, E.L., S.C. Tucker, and P.S. Williamson. 2003. Floral development in the Nymphaeales. International Journal of Plant Science 164: 5279-5292.
  • Lippok, B., A.A. Gardine, P.S. Williamson, and S.S. Renner. 2000. Pollination by flies, bees, and beetles of Nuphar ozarkana and N. advena (Nymphaeaceae). American Journal of Botany 87: 898-902.
  • Arsuffi, T.L., P.S. Williamson, M. de la Garza Newkirk, and M. Howard. 2000. The San Marcos River Wetlands Project: Restoration and environmental education in Texas. International Journal of Wilderness 6: 17-21.
  • Williamson, P.S. and C.R. Werth. 1999. Levels and patterns of genetic variation in the endangered species Abronia macrocarpa (Nyctaginaceae). American Journal of Botany 86: 293-301.
  • Arsuffi, T.L., P.S. Williamson, and M. de la Garza Newkirk. 1999. The San Marcos River Wetlands Project: Restoration and a vision of environmental stewardship and management for urban rivers in Texas through education and partnerships. 1998 River Management Society Symposium Proceedings pp. 161-170.
  • Williamson, P.S. and S.K. Bazeer. 1997. Self-incompatibility in Abronia macrocarpa. Southwestern Naturalist 42: 409-415.
  • Van Auken, O.W. and P.S. Williamson. 1997. Rare plants of the southwest: forward. Southwestern Naturalist 42: 367-368.
  • Schneider, E.L. and P.S. Williamson. 1996. Barclaya rotundifolia. Aqua-Planta 2: 87-95.
  • Janssen, G.K. and P.S. Williamson. 1996. Encouraging conservation of endangered plants on private lands: A case study of Frankenia johnstonii, an endangered south Texas subshrub. In: Southwestern Rare and Endangered Plants: Proceedings of the Second Conference. USDA Forest Service General Technical Report RM-GTR-283: 1-7.
  • Williamson, P.S. and E.L. Schneider. 1994. Floral aspects of Barclaya (Nymphaeaceae): Pollination, ontogeny and structure. Plant Systematics and Evolution 8: 104-115.
  • Williamson, P.S. and E.L. Schneider. 1994. Ondinea purpurea den Hartog. Aqua-Planta 1: 3-10.
  • Williamson, P.S., L. Muliani, and G.K. Janssen. 1994. Pollination biology of Abronia macrocarpa (Nyctaginaceae), an endangered Texas species. Southwestern Naturalist 39: 336-341.
  • Moseley, M.F., E.L. Schneider, and P.S. Williamson. 1993. Phylogenetic interpretations from selected floral vasculature characters in the Nymphaeaceae, sensu lato. Aquatic Botany 44: 325-342.
  • Williamson, P.S. 1991. Ondinea, the new Australian water lily. Water Garden Journal 7: 43-48.
  • Williamson, P.S. 1991. Ecological anatomy of Nuphar luteum leaves. Texas A&M University EM Views 6: 7-8.
  • Williamson, P.S. 1991. Crisis in Science: Creating an interest in botany. Native Plant Society of Texas Symposium Proceedings pp. 91-105.
  • Skubatz, H., P.S. Williamson, E.L. Schneider, and B.J.D. Meeuse. 1990. Cyanide-insensitive respiration in thermogenic flowers of Victoria and Nelumbo. Journal of Experimental Botany 41: 1335-1339.
  • Schneider, E.L., P.S. Williamson, and D.C. Whitenberg. 1990. Hot sex in water lilies. Water Garden Journal 6: 41-51.
  • Williamson, P.S., E.L. Schneider, and L.A. Malins. 1989. Tuber and leaf structure of Ondinea purpurea den Hartog (Nymphaeaceae). Western Australian Naturalist 18: 52-61.
  • Williamson, P.S. and M.F. Moseley. 1989. Morphological studies of the Nymphaeaceae (s.l.). XVII. The floral anatomy of Ondinea purpurea subspecies purpurea. American Journal of Botany 76: 1781-1796.
  • Moseley, M.F., I.J. Mehta, P.S. Williamson, and H. Kosakai. 1984. Morphological studies of the Nymphaeaceae (s.l.). XIII. Contributions to the vegetative and floral structure of Cabomba. American Journal of Botany 71: 902-924.
  • Schneider, E.L., M.F. Moseley, and P.S. Williamson. 1983. The pollination biology of Ondinea purpurea. Proceedings of the Vth International Symposium on Pollination. Ed. INRA Publ. Les Colloques de I'INRA, n-21: 231-235.


Chapters in Books

  • Williamson, P.S. and E.L. Schneider. 1993. Cabombaceae. In: The Families and Genera of Flowering Plants. K. Kubitzki, editor. Vol. II. Springer-Verlag, New York.
  • Williamson, P.S. and E.L. Schneider. 1993. Nelumbonaceae. In: The Families and Genera of Flowering Plants. K. Kubitzki, editor. Vol. II. Springer-Verlag, New York.
  • Schneider, E.L. and P.S. Williamson. 1993. Nymphaeaceae. In: The Families and Genera of Flowering Plants. K. Kubitzki, editor. Vol. II. Springer-Verlag, New York.


Laboratory Manuals

  • Elliot A.M. and P.S. Williamson. 1996. Laboratory Manual to Accompany The Botanical World. Wm. C. Brown Publishers, Iowa. 207 pp.
  • Elliot A.M. and P.S. Williamson. 1996. Instructor's Resource Guide for the Laboratory Manual to Accompany The Botanical World. Wm. C. Brown Publishers, Iowa. 45 pp.


Theses/Dissertations Directed

  • Florence M. Oxley – Ph.D., 2013.  Invasive potential of the aquatic macrophyte Cryptocoryne beckettii
  • ​Stefanie Ferrazzano – M.S., 2012.  Testing the effects of mycorrhizal fungi on growth and development of Abronia macrocarpa.
  • Sandy Birnbaum – M.S., 2009.  Testing population introduction of Astrophytum asterias.
  • Jacqueline Goodson – M.S., 2007. Testing population introduction of Abronia macrocarpa.
  • Andy Blair – M.S., 2007. Pollinator effectiveness, pollinator importance, and pollen dispersal in star cactus (Astrophytum asterias).
  • Carolyn G. Meredith – M.S., 2006. Recovery of Abronia macrocarpa following population disturbance.
  • Cyndee Baker – M.S., 2006. Estimating the probability of detecting Golden-cheeked warblers (Dendroica chrysoparia) using presence-absence surveys. (Co-advisor with Butch Weckerly)
  • Eric Atkins – M.S., 2006. A comparison of eradication techniques for a nonindigenous emergent plant species (Colocasia esculenta).
  • Anna W. Strong – M.S., 2005. Reproductive biology of Astrophytum asterias (Cactaceae).
  • Carrie K. Preite – M.S., 2002. Algal species composition on turtle carapaces in Spring Lake, Hays County, San Marcos, Texas.
  • Marsha M. Reimer – M.S., 2002. Baseline survey and checklist of birds at Spring Lake and surrounding vicinity, San Marcos, Hays County, Texas. (Co-advisor with Dave Huffman)
  • Darren P. Dodson – M.S., 2001. The effects of disturbance on Thymophylla tephroleuca, ashy dogweed (Asteraceae).
  • Patti L. Herzik – M.S., 1998. The seed biology of Frankenia johnstonii (Frankeniaceae).
  • Selvi K. Bazeer – M.S., 1996. Self-incompatibility in Abronia macrocarpa, large-fruited sand verbena (Nyctaginaceae).
  • Karen L. Couch – M.S., 1996. Seedling recruitment and plant recolonization of a disturbed population of Abronia macrocarpa (Nyctaginaceae).
  • Lisa Muliani – M.S., 1994. Breeding system and reproductive capacity of Abronia macrocarpa, large-fruited sand verbena (Nyctaginaceae).
  • Gena K. Hamilton – M.S., 1991. Reproductive biology and leaf structure of Abronia macrocarpa (Nyctaginaceae), an endangered Texas endemic.


Non-Theses Graduate Students Directed

  • Neil Schmidt – M.S.I.S., 2014.
  • Jennifer R. Mandel - M.S., 2004.
  • Luz E. Morris - M.S. 2004.
  • Christine F. Hudec - M.S. 2001.​


Curriculum Vita

Curriculum vita is available for download [PDF]

Current Professional Service

Board of Governors, Southwestern Association of Naturalists, 1991-Present.