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 pollen strobilus is less obviously compound in Pseudotaxus and reduced to a simple structure in Taxus and Torreya.
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.
He drew support for this position largely from the appearance of a similar ovulate strobilus in a Jurassic fossil conifer, the bladderless pollen of Taxaceae, and the intermingling of sterile and fertile scales in the pollen strobili of Pseudotaxus.