WIGGAM-HARPER, SHELLY D.* and CAROLYN J. FERGUSON. Division of Biology, Kansas State University, Manhattan, KS, USA 66506-4901. - Pollination biology of Phlox divaricata L. (Polemoniaceae): visitation, pollen threshold, and mating system in a Central Plains population.
Phlox divaricata is a widespread and variable species within a
group of taxa noteworthy for geographic variation and hybridization.
Pollination biology of this species is intriguing, and has not been
adequately investigated. Because observed flower visitors are not
necessarily sufficient pollinators, quantification of pollinator
effectiveness has become an integral part of pollination biology
studies, allowing a more accurate interpretation of the effects of
pollinators on plant floral and reproductive traits, the distribution
of individuals, population dynamics, and phylogeography. Phlox
divaricata has a wide geographical distribution, with the Central
Plains representing the westernmost portion of its range, where P.
divaricata occurs in scattered populations on rich slopes and
creek bottoms. This study focused on the tallgrass prairie of the
Central Plains. Visitors to P. divaricata were identified using
caging and observation to determine diurnal, crepuscular, and
nocturnal visitors and their effects on seed set. Additional studies
were conducted to document the breeding system of P. divaricata
and its pollen threshold. To look for shifts in pollinator types
across geographic regions, surveys of P. divaricata populations
along latitudinal and longitudinal transects were compared. These
results lay the foundation for experimental studies on the
effectiveness of individual visitors to P. divaricata.
Key words: Central Plains, mating system, Phlox divaricata, pollen threshold, pollination biology