Zooidogamy in the Late Permian genus Glossopteris

Abstract

We describe details of anatomically preserved fossil glossopterid ovules from the Late Permian of Queensland, Australia, that contain several pollen tubes at various stages of releasing flagellated sperm. Each sperm is approximately 12.7 microm long and 13.9 microm wide, with a conspicuous spiral structure comprised of a series of dots that resemble the position of basal bodies of flagella aligned along the multilayered structure (MLS). This configuration is similar to the helically arranged flagella in the sperm of cycads, Ginkgo, and many pteridophytes. However, the motile gametes of Glossopteris are considerably smaller than those of Ginkgo and cycads, and more similar in size, number of basal bodies, and number of gyres in their helix to pteridophyte forms. Glossopteris thus shares the intermediate stage of motile male gamete formation and apparently that of haustorial pollen tubes with cycads and Ginkgo.

New evidence of reproductive organs of Glossopteris based on permineralized fossils from Queensland, Australia. I. Ovulate organ Homevaleia gen. nov.

“…Vegetative leaves of Glossopteris homevalensis Pigg et McLoughlin, known only from this locality and G. schopfii Pigg and G. skaarensis Pigg, also present in Antarctica, have been described (Pigg and McLoughlin 1997). We recently documented ovules of the type described in this study that contain pollen tubes with flagellated sperm (Nishida et al 2003(Nishida et al , 2004. In this paper we describe Homevaleia gouldii H. Nishida, Pigg, Kudo et Rigby gen. et sp.…”

“…7) and the nucellus almost adheres to the integument, but the tentpole is lacking. Additional details of megagametophyte, archegonia, pollen tube, and sperm structure have been described in detail elsewhere (Nishida et al, 2003(Nishida et al, , 2004.…”

“…At the same time the pollen grains germinate in the pollen chamber, each forming a relatively short, thick pollen tube. We have discussed the structure of the pollen tube and its flagellated sperm elsewhere (Nishida et al 2003(Nishida et al , 2004.…”

Seed ferns from the late Paleozoic and Mesozoic: Any angiosperm ancestors lurking there?

“…Bisaccate pollen of the Protohaploxypinus Samoilovitch type (Fig. 7) has been reported in the pollen chambers of these ovules (Gould and Delevoryas, 1977; Nishida et al, 2004). Especially significant is the report of pollen tubes in various stages of releasing flagellated sperm in the region of the archegonium (Nishida et al, 2003).…”

Distinguishing angiophytes from the earliest angiosperms: A Lower Cretaceous (Valanginian‐Hauterivian) fruit‐like reproductive structure

“…The angiosperm identity of the Jurassic fossil genus Caytonia Thomas (Caytoniales; Thomas, 1925) was refuted by Harris (1940) after he macerated the compression/impression seeds from the cupules and found Vitreisporites Leschik pollen (the type found in Caytonanthus Harris 1933a) in the seed micropyles. Work by Gould and Delevoryas (1977) and subsequently by Nishida et al (2003, 2004, 2007) resulted in similar finds showing that Glossopteris Brongniart (Glossopteridales, also often implicated in angiospermy) had gymnosperm pollination and a reproductive cycle similar to cycads and Ginkgo .…”