Abstract: The monotypic genus Diplopanax Hand.-Mazz. of the south China and North Vietnam has been assigned by different authors to the Araliaceae, the Cornaceae and the Mastixiaceae. An investigation of floral, fruit, young stem and leaf anatomy confirmed the absence of secretory canals, one celled, two armed hairs, uniloculary ovar containing a single amphitropous ovule, these characters prelude the assignment of Diplopanax to the Araliaceae. This genus is the most similar to Mastixia based on morphological characters. The genus also possesses some features discordant in the Cornaceae, having epitropous ovules, horse-shoeshaped seed locule, cyme. Additionally, incomplete septum occurs in mastixiaoids fossil fruit of the upper Cretaceous, mastixoids is an independent evolution line. So the separate family Mastixiaceae enclosing Diplopanax and Mastixia is supported, and it is rather primitive in the order Cornales.

Key words: Diplopanax, Mastixiaceae, Cornaceae, Araliaceae, Morphological characters, Systematic implication