Pollen morphology of Zelkovia sicula (Ulmaceae), a recently discovered relic species of the Rueopean Tertiary flora: Description, chromosomal relevance and palaeobotanical significance.
Reference:
Nakagawa,T. et al. (1998)
Pollen morphology of Zelkovia sicula (Ulmaceae), a recently discovered relic species of the Rueopean Tertiary flora: Description, chromosomal relevance and palaeobotanical significance. Review of Palaeobotany and Palynology
Vol. 100 # 1 P. 27- 37