Pollen morphology of the East Asiatic genus Chelonopsis (Lamioideae: Lamiaceae) and allied genera, with reference to taxonomic implications and potential pollination ecology

Abstract

Pollen grains of 15 taxa of the genus Chelonopsis (14 spp. and 1 variety) from China and Japan and 6 species of the closely related genera Bostrychanthera (1 species) and Gomphostemma (5 species) were examined by light and scanning electron microscopy. Of these, the pollen morphology of 18 taxa was studied for the first time. Pollen grains were found to be tricolpate with polar lengths of 20.8–30.0 μm and equatorial widths of 17.5–27.3 μm. The basic shape of the pollen in most taxa is subprolate or prolate-spheroidal, but spheroidal, subprolate-spheroidal, oblate-spheroidal, and prolate-subprolate grains are also found in some species. The surface is generally reticulate or suprareticulate in Chelonopsis and granulate in Bostrychanthera. In comparison with those of Chelonopsis and Bostrychanthera, the pollen grain surfaces of Gomphostemma are more diverse. In Chelonopsis, pollen is taxonomically useful at the sectional level, and some grains provide enough characters for species delimitation. The potential pollination ecology of cellular hairs on the anthers of Chelonopsis and Bostrychanthera is also briefly discussed.

Keywords::

• Bostrychanthera
• Gomphostemma
• Lamioideae
• taxonomy
• tribe Gomphostemmateae

Acknowledgments

The authors are grateful to Mr. Xi-Kan Fan and Dr. Zong-Xin Ren for their technical assistance in SEM. The authors specially thank Dr Jacqueline Van De Veire for her valuable suggestions and her great help in editing the text, and also thank Prof. Carlo Blasi and two anonymous reviewers for their constructive suggestions that greatly improved the paper. This study was supported by the National Natural Science Foundation of China (Nos. 31100164 and 31110103911) and the Chinese Academy of Sciences Grants (KSCX2-EW-J24, KSCX2-EW-Z-1).