Biodiv Sci ›› 2011, Vol. 19 ›› Issue (5): 551-557.DOI: 10.3724/SP.J.1003.2011.07035

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Morphology and cytology of three flower phenotypes in a duodichogamous tree species, Acer mono

Zhang Lingzhi1,2, Shang Hui1,2, Luo Yibo1, Cheng Xin3, Bai Weining1,*()   

  1. 1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093
    2Graduate University of the Chinese Academy of Sciences, Beijing 100049
    3Forestry Department of Fushun Municipality in Liaoning Province, Fushun, Liaoning 113000
  • Received:2011-03-02 Accepted:2011-06-14 Online:2011-09-20 Published:2011-10-08
  • Contact: Bai Weining

Abstract:

Duodichogamy, where individual plants produce two batches of male flowers that are temporally separated by a batch of female flowers, is the rarest temporal sexual system in flowering plants. Duodichogamy is present in some species of Acer, whose flowers of the first (male I) and second male phases (male II) differ morphologically. To explore the influence of floral development on flower morphology and phenology, we used paraffin methods and light microscopy to compare morphological and cytological differences among male (I and II) and female flowers at different developmental stages. Our main results were as follows: the ovary of male I degenerated and disappeared quickly upon megaspore tetrad degeneration, and developed into macrosporocytes; while the ovary of male II degenerated gradually during this period and only traces of residual ovule remained in the fully-developed ovary; the failure of anthers of female flowers to dehisce might be caused by retardant degeneration of tapetum tissue and loss of lip cells, i.e. formation sterility. In conclusion, both pistil and stamen primordial could be found in male (I and II) and female flower buds at early phases of sex differentiation, but selective abortion occurred in later developmental phases.

Key words: Acer mono, duodichogamy, functional male and female flowers, morphology, cytology