Plant Diversity ›› 2018, Vol. 40 ›› Issue (01): 35-40.DOI: 10.1016/j.pld.2017.12.004

• Articles • Previous Articles    

Morphological study of floral nectaries in Euonymus and the probable origin of the echinate fruit surface

Chiyuan Yaoa,b, Yunjuan Zuoa, Cheng Dua, Jinshuang Maa   

  1. a Shanghai Chenshan Plant Science Research Center, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 201602, China;
    b University of Chinese Academy of Sciences, Beijing, 100049, China
  • Received:2017-08-15 Revised:2017-12-18 Published:2021-11-05
  • Contact: Jinshuang Ma
  • Supported by:
    This study was supported by the National Natural Science Foundation of China (Grant No. 31170179) and a grant from the Shanghai Municipal Administration of Landscaping and City Appearance (Grant No. F132428). We would like to thank Professor Quan-Ru Liu of Beijing Normal University for providing Glyptopetalum samples.

Abstract: A conspicuous nectary disk is common but has a distinguishing morphology in the cosmopolitan genus Euonymus. Our study focuses on the morphology of floral nectaries in 21 representatives of Euonymus and Glyptopetalum. Two main types of nectaries were documented:a mix of inter-and extrastaminal nectaries existed between the corolla and the stigma, while the intrastaminal nectaries were distributed between the stigma and the stamen bases. The main route of nectar release in Euonymus is via modified stomata, and different nectarostomata locations were observed:in depressions, slightly raised above the epidermal surface or at the same level as the epidermis. Floral nectaries in E. sect. Echinococcus species developed into the protrusions on the fruit surface at the later stage. The development of nectaries not only explained the mystery of the origin of the echinate fruit surface, but also showed that differences in fruit surface might be inappropriate for use in infrageneric classification. These discoveries inform morphological observations of floral nectaries in Euonymus.

Key words: Nectary, Nectarostomata, Location, Protrusion