Anomalous pollen cones in Pseudotaxus chienii (Taxaceae) : A further support for the pseudanthial origin of the Taxus pollen cone

Abstract

Pseudotaxus pollen cones are compound inflorescences. Wild type and anomalous shaped pollen cones were studied. It is suggested that each perisporangiate microsporangiophore represents a strongly reduced flower (lateral pollen cone) and not a peltate microsporophyll. This explains their position in the axil of a scaly pherophyll. In the wild type, the axis of the flowers is so strongly reduced that it is no longer visible and the primordia of all inserted hyposporangiate microsporangiophores get in contact and fuse to a radial synangium. In some cases, the perisporangiate microsporangiophores/flowers were reduced to a single hyposporangiate microsporangiophore. This shows that the perisporangiate microsporangiophores of Pseudotaxus are not sporophylls, but strongly reduced lateral flowers, each consisting of several lateral hyposporangiate microsporangiophores, which fuse to a radial unit. By a reduction of all pherophylls in the Pseudotaxus inflorescence, the flower-like Taxus pollen cone structure is formed, which however represents an inflorescences with flowers reduced to perisporangiate microsporangiophores. If in Taxus pollen cones the lateral flowers get reduced to a single hyposporangiate microsporangiophore, the Torreya pollen cone is formed. In this case, the lateral hyposporangiate microsporangiophores of Torreya correspond to strongly reduced flowers and not to dorsiventral sporophylls.