SALTER, JOSHUA* AND JOHN E. BRAGGINS. School of Biological Sciences, University of Auckland, Auckland, New Zealand. - Comparative embryology of two New Zealand forest giants, Prumnopitys taxifolia and P.ferruginea (Podocarpaceae).
An embryological study is being done on two New Zealand podocarp
species, Prumnopitys taxifolia (matai) and P. ferruginea
(miro), firstly, to fill gaps in our knowledge of their embryogeny,
and secondly, to ascertain whether any differences may have taxonomic
significance. During 3-4 annual cycles specimens of male and female
cones have been collected and fixed at successive stages of
development. Most specimens were embedded in paraffin wax, sectioned
and stained for light microscopy, while some were embedded in resin
for both LM and TEM. Later stages of embryo development were obtained
from seeds collected, planted and exhumed at regular intervals leading
up to germination. Several developmental stages not illustrated in
the literature have been observed so far, and comprehensive life
cycles have been constructed for both species. Two stages of
taxonomic potential will be discussed: 1. the fertilization mechanism,
and 2. the structure and development of the proembryo shortly after
fertilization. The tiered proembryo in these podocarps conforms to
the basal plan more typical for conifers than the derived embryogeny
of the Pinaceae. The unusual fertilization mechanism observed in
these two species has only been observed in one other conifer,
Prumnopitys andina, their closest Chilean relative.
Key words: conifer embryology, fertilization mechanism, New Zealand podocarps, Podocarpaceae, Prumnopitys