Florin (1948, 1958) argued that Taxus and its related genera Amentotaxus, Austrotaxus
, Pseudotaxus, and Torreya differed significantly from other conifers and should be segregated in their own class, mainly because the ovule is terminal on a shoot in this group and lateral in other living conifers.
Austrotaxus and Pseudotaxus are known only from New Caledonia and the Zhejiang (Chekiang) Province, China, respectively.
The Taxaceae are a family of five genera and 25 species (including 2 artificial hybrids) distributed in the northern hemisphere except for the monotypic Austrotaxus, which occurs in New Caledonia, and one species of Taxus in Indonesia [ILLUSTRATION FOR FIGURE 1 OMITTED].
The compound pollen strobilus in Amentotaxus and Austrotaxus easily distinguishes these genera from all other conifers.
Resin is organized into a canal in the leaves of Amentotaxus (Keng, 1969), appears in scattered cells in the foliar parenchyma of Torreya, is found only in the roots and wounded stems of Taxus (Bliss, 1918), and is lacking in Pseudotaxus and Austrotaxus.