In many conifers, but by no means all, the ovule is borne not directly in the axil of the cone scale (bract), as it should if it were a simple structure, analogous to a flower, but on a secondary axis, the ovuliferous scale, itself directly in the axil of the bract scale, as if the cone were analogous to an inflorescence.
Within several groups of conifers a reduction series can be demonstrated in which the ovuliferous scale, assumed to be present ancestrally, has disappeared.
3m, n), each subtending an ovuliferous scale consistently bearing two adaxially placed ovules, their micropyles directed toward the cone axis.
These include at least five morphotypes of Glossopteris leaves and the glossopterid ovuliferous
organs Lidgettonia africana, Rigbya arberioides and Plumsteadia gibbosa, and the glossopterid polleniferous organ Eretmonia natalensis.
Proof of this are the petrified pine cones found with their ovuliferous
scales, still unopened, a development that requires only seventy-two hours.
8), the axis of the short shoot had become rudimentary and bore five distal sterile scales and two or three basal stalk-like megasporophylls, the whole, with the subtending bract, corresponding to the bract and ovuliferous
scale of a modern pine cone.
There is no evidence of ovuliferous scales subtended by bracts.
Conifers with an evident ovuliferous scale could be derived from the Lebachia type and the Cephalotaxaceae from the Ernestiodendron type.
For example, except for somewhat greater fusion of elements of the ovuliferous scale, the variation in Telemachus Anderson (Yao, Taylor & Taylor, 1993) and Florinostrobus (Delevoryas & Hope, 1987) is represented by that in Swedenborgia, Tricranolepis and Voltzia for purposes of the cladistic analyses.
Controversy has centered on the nature of the megasporangial enclosure or ovular integument and the interpretation of the ovuliferous scale.
In these the fleshy structure comprises part or all of the ovuliferous scale, sometimes fused with the subtending fertile bract.
were included in the Taxaceae (Pilger, 1903, 1916b) on account of their reduced ovuliferous scales and fleshy ovulate strobili.