Comparative floral ecology of bicolor and concolor morphs of Viola pedata (Violaceae) following controlled burns


  • Peter Bernhardt Saint Louis University
  • Retha Edens-Meier Saint Louis University
  • Dowen Jocson Saint Louis University
  • Justin Zweck Saint Louis University
  • Zong-Xin Ren Kunming Institute of Botany (Chinese Academy of Sciences)
  • Gerardo R. Camilo
  • Michael Arduser Missouri Department of Conservation (retired)



We compared pollination and seed set of bicolor and concolor morphs in self-incompatible, Viola pedata over two seasons in two populations of unequal sizes.  One population grew on a wooded slope (CR) and the second on an exposed glade (SNR).  Both were burned in 2014. The number of flowers produced by concolor plants at SNR was higher in 2014 while the number of flowering bicolors increased at CR in 2015. Petal temperatures, regardless of site, showed that dark purple, posterior petals of bicolors were consistently warmer than their own mauve-lilac, anterior (lip) petals and the all mauve petals of concolors. Major pollen vectors were female bees (Andrenidae, Apidae and Halictidae) but polylectic, Andrena carlinii dominated both sites.  Bees foraged on flowers upside down or right side up but neither mode correlated with either morph. Bees foraged preferentially on concolor at both sites.  Pistils containing pollen tubes were higher in concolor pistils at both sites with a marginally greater number of  tubes penetrating concolor ovules regardless of site or year.  While both populations produced more seeds in 2014 SNR plants always produced more seeds than CR plants.  The increasing numbers of bicolor plants at CR in 2015 suggested that bicolors may equal or outnumber concolors when dark petals offer additional warmth to ectothermic pollinators in a shady (cooler) forest vs. an open, sunny glade. Subtle environmental factors may give a floral trait a selective advantage influencing fitness in an unbalanced polymorphism persisting in localized populations.

Author Biographies

Peter Bernhardt, Saint Louis University

Department of Biology

Professor of Biology

Retha Edens-Meier, Saint Louis University

School of Education


Dowen Jocson, Saint Louis University

Department of Biology

graduate student (PhD)

Justin Zweck, Saint Louis University

Department of Biology

Graduate Student(PhD)

Zong-Xin Ren, Kunming Institute of Botany (Chinese Academy of Sciences)

Key Laboratory for Plant Diversity and Biogeography of Wast Asia

Associate Professor

Michael Arduser, Missouri Department of Conservation (retired)

Missouri Department of Conservation (retired)
Rosettes of concolour morphs of Viola pedata, growing in an exposed, sunny, dolomite glade outnumbered bicolour morphs by 40:1 over two seasons.  In contrast, bicolours equaled or outnumbered concolours in a forested, shady slope over two seasons.  Burnin




How to Cite

Bernhardt, P., Edens-Meier, R., Jocson, D., Zweck, J., Ren, Z.-X., Camilo, G. R., & Arduser, M. (2016). Comparative floral ecology of bicolor and concolor morphs of Viola pedata (Violaceae) following controlled burns. Journal of Pollination Ecology, 19, 57–70.