Female-biased nectar production in the protandrous, hermaphroditic shrub Salvia hierosolymitana (Lamiaceae)

Yehoram Leshem, Tamar Keasar, Avi Shmida

Research output: Contribution to journalArticlepeer-review


Flowering progresses upward along vertical inflorescences in the protandrous dichogamous shrub Salvia hierosolymitana (Boiss.). Flowers' gender nectar production rates and their vertical distribution were recorded in two populations (northern and central Israel) over 3 years. Female-phase flowers produced significantly more nectar than male-phase flowers and were more abundant at the inflorescences' base. Thus, nectar availability gradually decreases along inflorescences. Female-biased nectar production can benefit plants by increasing pollinator visits to female-phase flowers, enhancing pollination success when pollen is scarce. In congruence with this hypothesis, the following observations suggest that pollen in S. hierosolymitana may be in short supply: (1) freshly dehisced anthers contained 40% of sterile pollen; (2) pollen counts on female-phase stigmas were low (mean±s.e. 11.6±1.56); and (3) counts of germinated pollen tubes at the pistils' base were even lower (5.02±0.54). The nectar gradient along the inflorescence may also be adaptively beneficial in other aspects. Foraging insects that follow this gradient are expected to move from female-phase flowers near the inflorescences' base, to male-phase flowers closer to the top. Thus, reducing the risk of geitonogamy and promoting outcrossing while moving from male-phase flowers of one individual to female-phase flowers of another.

Original languageEnglish
Pages (from-to)18-25
Number of pages8
JournalAustralian Journal of Botany
Issue number1
StatePublished - 2011

Bibliographical note

Funding Information:
We thank Mimi Ron and Ori Fragman-Sapir from the Hebrew University botanical gardens at Mount Scopus and Givat-Ram, respectively, for essential assistance, Alex Levine from the Department of Plant Sciences at the Hebrew University for help with laboratory facilities, Yaron Shaul and Shay Yerushalmi for assistance in field work and Smadar Peleg-Grossman for help with the imaging. We are grateful to Tom de Jong from Leiden University for critical reading of the manuscript and to the two anonymous reviewers for their comments. Sadly, Professor Tzvi Sachs from the Department of Plant Sciences in the Hebrew University who encouraged this study, passed away before completion of the work. The study was supported by the Centre for Rationality and by the Institute for Advanced Studies at the Hebrew University.

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science


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