Nectar sugar production across floral phases in the Gynodioecious Protandrous Plant Geranium sylvaticum [corrected]

PLoS One. 2013 Apr 22;8(4):e62575. doi: 10.1371/journal.pone.0062575. Print 2013.


Many zoophilous plants attract their pollinators by offering nectar as a reward. In gynodioecious plants (i.e. populations are composed of female and hermaphrodite individuals) nectar production has been repeatedly reported to be larger in hermaphrodite compared to female flowers even though nectar production across the different floral phases in dichogamous plants (i.e. plants with time separation of pollen dispersal and stigma receptivity) has rarely been examined. In this study, sugar production in nectar standing crop and secretion rate were investigated in Geranium sylvaticum, a gynodioecious plant species with protandry (i.e. with hermaphrodite flowers releasing their pollen before the stigma is receptive). We found that flowers from hermaphrodites produced more nectar than female flowers in terms of total nectar sugar content. In addition, differences in nectar production among floral phases were found in hermaphrodite flowers but not in female flowers. In hermaphrodite flowers, maximum sugar content coincided with pollen presentation and declined slightly towards the female phase, indicating nectar reabsorption, whereas in female flowers sugar content did not differ between the floral phases. These differences in floral reward are discussed in relation to visitation patterns by pollinators and seed production in this species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbohydrates / biosynthesis*
  • Flowers / growth & development
  • Flowers / metabolism*
  • Geranium / growth & development
  • Geranium / metabolism*
  • Hermaphroditic Organisms / growth & development
  • Hermaphroditic Organisms / metabolism
  • Plant Nectar / metabolism*
  • Pollination
  • Reward


  • Carbohydrates
  • Plant Nectar

Grant support

This work was supported by the Finnish Cultural Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.