EPOW - Ecology Picture of the Week

The Spiderwort That Isn't

Ohio Spiderwort or Bluejacket (Tradescantia ohiensis), Family Commelinaceae
Jean Lafitte National Historic Park and Preserve, Louisiana, USA

Explanation:  This beautiful native of fields and wetlands occurs widely through eastern and central States of the U.S.  But we are at the very edge of its distributional range along the Gulf Coast ... here in Jean Lafitte National Historic Park and Preserve, in the bayous of southern Louisiana.

Throughout its range, Ohio spiderwort -- perhaps better referred to by its alternate name of bluejacket, because it is found, obviously here, well outside Ohio -- forms hybrids with a number of (at least nine) related species.  

And here's the point of all this:  species occurring on the edge of their distributional range sometimes are found in anomalous habitats (such as bayous, in this case) and undergo genetic differentiation (sometimes hybridizing with other species), as the advent of the evolution of new subspecies or species (Csergő et al. 2011, Herlihy and Eckert 2005).  

Whether this is the case with Ohio spiderwort -- I mean bluejacket -- in the southern Louisiana bayous is apparently unstudied, but the situation seems ripe for study.  This could be a case of the spiderwort that isn't quite a spiderwort ... 
  

Information:
     Csergő, A.-M., E. Molnár, and M. B. García. 2011. Dynamics of isolated Saponaria bellidifolia Sm. populations at northern range periphery. Population Ecology 53(2):393-403.
     Herlihy, C. R., and C. G. Eckert. 2005. Evolution of self-fertilization at geographical range margins? A comparison of demographic, floral, and mating system variables in central vs. peripheral populations of Aquilegia canadensis (Ranunculaceae). American Journal of Botany 92(4):744-751.
     Parrish, J.A.D. and F.A. Bazzaz.  1979.  Difference in pollination niche relationships in early and late successional plant communities.  Ecology 60(3):597-610.
     Sinclair, C.B.  1968.  Pollination, hybridization, and isolation factors in the erect Tradescantias.  Bulletin of the Torrey Botanical Club 95(3):232-240.
     Sparrow, A.H. and R.C. Sparrow.  1976.  Spontaneous somatic mutation frequencies for flower color in several Tradescantia species and hybrids.  Environmental and Experimental Biology 16(1):23-43.
     Tucker, G.C.  1989.  The genera of Commelinaceae in the southeastern United States.  Journal of the Arnold Arboretum 70(1):97-130.