One can regard the plant body of Phylloglossum as paedomorphic, as Wikstrom and Kenrick (1997) do, in that it produces so few leaves and only one root, and yet produces a strobilus
with this minimal vegetative apparatus.
The only extant coniferophytes with micro- and mega-sporophylls in the same strobilus are the Gnetales, but they are functionally unisexual so that plants are dioecious.
Table 1 Sequence of events in the development and function of the ovulate strobilus of seed plants Structure Process "Gymnosperms" "Angiosperms" Strobilus Initiation Pre-ovulate Pre-ovulate (flower) Ovule Induction Angio-ovuly Angio-ovuly Pollination Gymno-ovuly (a) Angio-ovuly (b) Seed Embryo Gymnospermy (e.
In Walkomiella (Feistmantel) Florin, from the Late Permian of Australia, ovules are associated with leaves in a strobiloid organ (White, 1981), but the strobilus appears to be a simple rather than a compound.
Again, evidence of a compound ovulate strobilus is lacking.
He documented the nature of the bract and axillary fertile strobilus of the latter and illustrated variations in forms.
This contrasts with the strobilus in Juniperus and in the other gymnosperm family with a fleshy reproductive structure, the Podocarpaceae.
The microsporangiate strobilus of gymnosperms is simple, but within the Taxaceae and the Cephalotaxaceae there are clear examples of compound pollen strobili, and those that appear simple are currently interpreted to be reduced compound structures (Keng, 1969; Wilde, 1944, 1975).
However, leaf and ovulate strobilus morphology and many other characteristics that are similar to other Taxaceae, particularly Torreya, suggest retention of Amentotaxus in the Taxaceae (Florin, 1948, 1951; Janchen, 1934; Keng, 1969, Koidzumi, 1932; Li, 1952).
The compound pollen strobilus in Amentotaxus and Austrotaxus easily distinguishes these genera from all other conifers.
Florin (1948c, 1951, 1954) caused much of the controversy with his assertion that the single, terminal ovule of the Taxaceae (often referred to as the "uniaxial cone," in order to distinguish it from the reduced strobilus of the Podocarpaceae) is a primitive feature.
The pollen strobilus of Amentotaxus lacks bracts but otherwise strongly resembles the compound arrangement of the pollen strobilus of Cephalotaxus.