species of Taxaceae

Cephalotaxaceae and Podocarpaceae have been investigated with the TEM for ultrastructural characters from their sieve elements

of which 10 species are studied for the first time. Quantitative data from sieve-element plastids(size

as well as average diameter and number of their contents)is also used to deduce the phylogenetic relationship. All of the species tested contain S-type plastids

and the starch grains are of the same shape within genus. In Taxaceae

the ultrastructure of Taxus are similar to that of Amentotaxus

while Pseudotaxus resemble Torreya. In Cephalotaxaceae

it is found that C. oliveri is quite different from the rest members within the same genus

Cephalotaxus

what supports to divide the genus into two sections

Sect. Pectinatae and Sect. Cephalotaxus. It is reasonable to include Sect. Nageia in Podocarpaceae.