Morphology and anatomy of male cones of Pseudotaxus chienii (W.C. Cheng) W.C. Cheng (Taxaceae)

Abstract

a b s t r a c tResults of the present study indicate that male cones of Pseudotaxus chienii are representing inflorescences with strongly reduced flowers. The results fit quite well with investigations showing that sporangiophores of Taxus and also of Pseudotaxus comply with reduced flowers. The only difference between male cones in Taxus and Pseudotaxus is the absence of pherophylls in Taxus. Furthermore our results complete a transition series beginning with Cephalotaxus going on to Pseudotaxus and ending with Taxus and Torreya. In this progression Pseudotaxus can be regarded as an intermediate link between the inflorescences of Cephalotaxus and the simple, unbranched cones of Taxus. The entire transition series shows that sporophyll-like sporangiophores can be derived by reduction of lateral cones. There is however no sign that a similar process has occurred in other conifer groups. (T. Stützel). 1 We avoid using the term "sporophyll" or "microsporophyll" for the sporangia bearing structure. Otherwise we would have introduced a priory a homology with the terminology applied, which we want to analyze in our comparative study. 0367-2530/$ -see front matter

Pollen cone teratologies in Sequoia sempervirens (D. Don) Endl. and Widdringtonia nodiflora (L.) Powrie (Cupressaceae) in the light of conifer evolution

“…nodiflora are quite remarkable, because among extant conifers, this type occurs only in Taxaceae (Wilde, ; Mundry & Mundry ; Dörken et al. ; Dörken & Nimsch ). Even today the evolutionary origin of coniferous microsporangiophores remains controversial.…”

“…In perisporangiate microsporangiophores of Taxaceae the microsporangia and the peltate scutellum are always fused to each other (Mundry & Mundry ; Dörken et al. ; Dörken & Nimsch ). Dörken and Nimsch () who investigated the vasculature within microsporangiophores of Taxaceae in detail, could clearly show that the perisporangiate type represents a fusion product of several fused hyposporangiate microsporangiophores.…”

“…In previous studies on male reproductive structures in Taxaceae, the simple, uniaxial structure of pollen cones in Taxus or Torreya is suggested to be derived from a compound, polyaxial ancestral condition comparable to the one still developed in extant species of Cephalotaxus and the hyposporangiate microsporangiophores of Torreya as derived from an ancestral perisporagiate type (e.g. Mundry & Mundry 2001;D€ orken et al 2011;D€ orken & Nimsch 2016).…”

“…Cephalotaxus and Pseudotaxus (Wilde ; Mundry & Mundry ; Dörken et al. ; Dörken & Nimsch ), and within Cupressaceae only Juniperus drupacea (Lemoine‐Sébastian ) and some Podocarpaceae e.g. Podocarpus , Retrophyllum and Prumnopitys (Schulz et.…”

“…Polyaxial, compound, inflorescence-like pollen cones occur only within Taxaceae e.g. Cephalotaxus and Pseudotaxus (Wilde 1975;Mundry & Mundry 2001;D€ orken et al 2011;D€ orken & Nimsch 2016), and within Cupressaceae only Juniperus drupacea (Lemoine-S ebastian 1967) and some Podocarpaceae e.g. Podocarpus, Retrophyllum and Prumnopitys (Schulz et.…”