Upper Carboniferous seed fern (Pteridospermophyta) pollen organs from Silesia (Poland) and related evolution considerations

Extinct seed ferns (Pteridospermophyta) fill a key position in the evolutionary tree of seed plants. Their reproductive structures enable to recognition of the interrelationship within seed ferns and other seed plants descending from them. Seed fern reproductive structures from Poland are very rarely found and very poorly known, especially the pollen organs to which this paper is dedicated. A new genus and species <em>Silesiatheca formosa</em><em> </em>Pacyna &amp; Zdebska, gen. et sp. nov. of lyginopteridalean aggregated synangia was recognized based on specimens preserved within sideritic nodules from Sosnowiec. The genus <em>Codonotheca </em>is recognized from European Carboniferous for the first time. The least evolutionarily advanced species of <em>Codonotheca</em><em> </em>− <em>Codonotheca</em><em> silesiaca</em><em> </em>Pacyna &amp; Zdebska sp. nov., is described based on specimens with weakly expressed radial symmetry and slight fusion of the sporangia. this species matches the hitherto hypothetical simplest species of <em>Codonotheca </em>very well, constituting the initial form for all the more compound pollen organs of Medullosales. For the first time in the European Carboniferous the North American species <em>Aulacotheca campbellii </em>(White, 1900) Halle, 1933 is recognized. A new emended diagnosis for the typical species <em>Boulayatheca fertilis </em>(Kidston, 1914) Taylor &amp; Kurmann, 1985 is proposed, based on specimens from Poland. Two new species of genus <em>Boulayatheca </em>Taylor &amp; Kurmann, 1985 are recognized. <em>Boulayatheca ciliata </em>Pacyna &amp; Zdebska, sp. nov. with a synangium surface covered with hairs (a feature hitherto unknown in the <em>Boulayatheca </em>genus) and <em>Boulayatheca saganii </em>Pacyna &amp; Zdebska, sp. nov<em>. </em>with a markedly elongated synangium. Occurrence of <em>Whittleseya </em>Newberry, 1853a emend. Halle, 1933 typical species <em>− Whittleseya elegans </em>Newberry, 1853a was confirmed in Lower Silesia based on new specimens. Some specimens referred to earlier in the literature as <em>W. elegans </em>were ascribed here to the new species <em>W. silesiaca</em><em> </em>Pacyna &amp; Zdebska, sp. nov<em>.</em>, which differs from typical species in synangium shape and sporangia clustering into groups. The new species <em>Whittleseya campanulata </em>Pacyna &amp; Zdebska, sp. nov<em>. </em>has a large synangium and sporangia clustering into groups. Heterogeneity within the genus <em>Whittleseya </em>is recognized, where some species, including those new described here, probably formed compound synangia. The aggregated synangia of Medullosales are recognized in thecompression state of preservation for the first time they are the base for establishing a new genus and species <em>Kotasotheca annaeadamii </em>Pacyna &amp; Zdebska, gen. et sp. nov. The genus <em>Dolerotheca</em><em> </em>Halle, 1933 was recognized in the Polish Carboniferous for the first time and a new species <em>Dolerotheca migierii</em><em> </em>Pacyna &amp; Zdebska, sp. nov. was described. T.N. Taylor’s model of evolution of medullosalean pollen organs was confirmed, and the new taxa described were included within it.

Tapetum character states: analytical keys for tapetum types and activities

The different types of tapetum found in the spermatophyta are described, along with associated characters. The characters (taken singly, pairwise, or in multiple combinations) are (i) tapetum types; (ii) cell walls, tapetum types, and loculus; (iii) tapetal cells individually, tapetum types, and loculus; (iv) number of pollen grains enveloped by tapetal cells and type of pollen dispersing unit; (v) cell types and tapetum types; (vi) number of nuclei per cell and tapetum type; (vii) cycles of hyperactivity; (viii) exine formation; (ix) orbicles; (x) peritapetal membrane; (xi) plastid differentiation; (xii) stage of pollen development in which tapetal cells degenerate and type of pollen coat; (xiii) storage vacuoles; (xiv) sporophytic proteins; and (xv) devices of tapetal origin responsible for compound pollen formation and pollination. Examples are given and an analytical key of structural and functional diversity is provided as a helpful approach to the study of the tapetum. Key words: tapetum types, activities, pollen dispersing units.

Morphological and embryological studies in Nymphaeaceae. II. Brasenia schreberei Gmel. and Nelumbo nucifera Gaertn

The stamens are whorled in Brasenia schreberei and spirally arranged in Nelumbo nucifera. The anther is tetrasporangiate. Parietal layers are five-celled in thickness in B. schreberei and six-celled in N. nucifera. Endothecial cells contain a tannin-like substance and develop fibrous thickenings in N. nucifera. The middle layers are persistent in N. nucifera and ephemeral in B. schreberei. The tapetal cells become multinucleate and the layer develops cutinization on its inner walls in N. nucifera. It is secretory. Micronuclei are formed at the meiosis in the microspore mother cells. These degenerate in B. schreberei and form micropollen grains in N. nucifera. Polysporads and compound pollen grains occur frequently in the latter. Pollen sterility is common. In B. schreberei the carpel is horseshoe-shaped, unites with its margins, and bears two to three pendulous ovules with lamina1 placentation. The carpel in N. nucifera, however, remains open in its early development, unites by the growth of the interlocking hairs, and contains a single ovule. A single parietal layer is present in B. schreberei, and four to five such layers in N. nucifera. A hypostase is formed in B. schreberei. The nucellus functions as perisperm in the latter and is consumed early in N. nucifera. A linear megaspore tetrad is formed in which the chalazal megaspore is functional. The embryo sac is of the Polygonum type. The antipodal cells are ephemeral in B. Schreberei and persistent with secondary multiplication in N. nucifera. In post-fertilized ovules one of the synergids is persistent. Fertilization is non-synchronous in N. nucifera and simultaneous in B. schreberei. In N. nucifera the antipodal cells become enlarged and multinucleate, and occupy the elongated tube formed by the downward penetration of the embryo sac. They degenerate at the early globular stage of the embryo and are not persistent when the embryo is pear-shaped. In B. schreberei a transverse cytokinesis follows division of the primary endosperm nucleus and two unequal cells are formed. The small chalazal endosperm cell penetrates the nucellus below and forms a long tube-like haustorium occupying three-quarters of the length of the nucellus. Its nucleus subsequently hypertrophies and degenerates completely at the globular stage of the embryo. Endosperm is ab initio cellular in B. schreberei and free nuclear in N. nucifera.