Douglas, Inflorescence development in Carnarvonia 
751 
characterized by the presence of flower pairs, each pair representing the products of 
first-order axillary meristems, analagous to a floral meristem on an inflorescence 
(Douglas & Tucker 1996a). The inflorescence of Carnarvonia differs from other 
Proteaceae in that: it is paniculate in outline; it appears to have complex and irregular 
branching patterns; the smallest inflorescence branch units tend to be composed of 
two to four flowers, one of which is at the base of the inflorescence branch; 
inflorescences can develop from proleptic or sylleptic buds; inflorescence positions 
can be axillary on old or new growth or even represent the terminal portion of the 
shoot; and the flower, depending on its position on an inflorescence, can either have 
or lack a subtending bract (Fig. 1). 
Implied in phylogenetic relationships are hypotheses of morphological changes of a 
homologous structure. Diverse forms of flowers and inflorescences are necessarily 
the products of differences in ontogenetic processes within each system. The 
hypothesized relationship of Carnarvonia as having shared a common ancestor with 
a taxon within Grevilleoideae (Engler 1889, Venkata Rao 1971) or as having a common 
ancestor with Grevilleoideae (Johnson & Briggs 1975) implies a divergence of 
developmental patterns in inflorescence construction that is either derived from the 
basic 'grevilleoid raceme' and flower pair condition found within Grevilleoideae in 
the former or from a 'common-groundplan' with Grevilleoideae in the latter. Within 
a developmental comparative context, the specific processes that result in a particular 
or novel morphology can be assessed (Wardlaw 1952, Fink 1982). Additionally, a 
developmental morphological study necessarily increases the available information 
concerning a specific morphological form. This is an essential element in 
understanding evolutionary changes in form, particularly when taxa share common 
parts of a form but have different manifestations of the parts within the form. Thus, 
a comparative examination of the development of the inflorescence and flowers of 
Carnarvonia could yield insights into the common and divergent elements of 
construction involved in inflorescence architecture as well as provide criteria of 
homology for future phylogenetic analyses. 
As part of an ongoing comparative developmental study of flower and inflorescence 
diversity in Proteaceae, this study describes the developmental events responsible 
for inflorescence and floral form in Carnarvonia and specifically aims to determine 
the basic developmental groundplan of the inflorescence using metameric concepts. 
Subsequently, these data will be used to examine the hypotheses related to the 
phylogenetic derivation of the Carnarvonia inflorescence and the grevilleoid flower- 
pairs and define the hypothetical changes that can or have occured in the 
diversification of inflorescences among Proteaceae. 
Materials and methods 
Specimens were obtained from multiple plants and populations from Mt Lewis, 
QLD. Additional material from cultivated wild plants was obtained from Yuruga 
Nursery, QLD. Floral and inflorescence material for developmental investigations 
was fixed in FA A (formalin - acetic acid - 50% ethanol; 5:5:90) and subsequently 
rinsed and stored in 70% ethanol. Inflorescence and floral materials were micro- 
dissected in 100% ethanol under an Olympus SZH-10 photo-dissecting microscope 
with Schott KL-1500 fiber-optic illumination. Dissected materials were further 
dehydrated in an ethanol-acetone series. Due to the extreme density of hairs, even 
at the earliest stages of ontogeny, some materials were redissected in acetone, the 
trichomes being removed individually in many cases. After dissections, dehydration 
and critical point drying, the material was mounted on aluminum stubs using 
colloidal graphite and sputter coated with ~ 100-400 nm of gold. In some cases. 
