Flexibility of resource allocation in a hermaphroditic-gynomonoecious herb through deployment of female and male resources in perfect flowers.
OBJECTIVE
It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female-biased allocation increases with plant size in the hermaphroditic-gynomonoecious herbEremurus anisopterus.


METHODS
Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types ofE. anisopterus.


RESULTS
Frequency of gynomonoecious plants varied from 2-17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites.


CONCLUSIONS
Although the prediction of an increase in female flower number with plant size was not observed inE. anisopterus, the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female-biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants.
Xinjiang Key Laboratory of Grassland Resources and Ecology and Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology, College of Grassland and Environment Sciences, Xinjiang Agricultural University, Ürümqi 830052, China.
Jannathan
J
Mamut
Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
Ying-Ze
YZ
Xiong
Xinjiang Key Laboratory of Grassland Resources and Ecology and Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology, College of Grassland and Environment Sciences, Xinjiang Agricultural University, Ürümqi 830052, China tandunyan@163.com hsq@mail.ccnu.edu.cn.
Dun-Yan
DY
Tan
Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan 430079, China tandunyan@163.com hsq@mail.ccnu.edu.cn.
Shuang-Quan
SQ
Huang
D035264:Flowers / Q000254:growth & development / Q000502:physiology*; D057850:Hermaphroditic Organisms / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D012098:Reproduction; D019849:Sex Determination Processes; D000070380:Asphodelaceae / Q000254:growth & development / Q000502:physiology*
Eremurus anisopterus; Liliaceae; Xanthorrhoeaceae; female flowers; floral sex allocation; floral traits; gynomonoecy; nectarless; perfect flowers; plant size