Douglas, Inflorescence development in Carnarvonia 
767 
a and P prophylls (in dicots). Depending on the position of the axillary meristem in 
relation to other axillary branches on the main or subunit axis, the meristem can 
become a flower (Fig. 66A'; distal parts of subunits or main axis) or an a-phyll can 
be initiated (Fig. 66B). If an a-phyll is initiated, a meristem develops in its axis and 
the meristem can either senesce (Fig. 66B') or can enlarge, giving rise to a floral or 
subunit meristem (Fig. 66C'-G). These processes, starting with an axillary meristem, 
can be repeated with each successive metamer (arrows to 'A' — Figs 66C-G'). 
The complexity of the inflorescence is not due to the number or arrangement of the 
parts but rather to the degree of reiteration of the developmental pattern at different 
hierarchical levels within the inflorescence. In this sense, the elaboration of the 
inflorescence is the product of differential proliferation of a shared developmental 
pathway within each subunit. The same developmental pathway found in the primary 
axis is present in the secondary, tertiary and higher axes resulting in a hierarchical 
arrangement of complexity. The fate of each axillary meristem is thus the product of 
the competence and extent to which the meristem will repeat the patterns expressed 
at lower hierarchies. In addition, the number of flowers on any one subunit appears 
to be related to the presence or absence of the a-phyll. 
Towards the end of a subunit axis or the primary axis, one, two or three flowers will 
develop, usually all but one of the flowers are in a bract axil. In the case of three 
flowers, one flower is the product of the axillary meristem in the a-phyll and two 
are the product of the subunit axis, one generally developing in the axil of the 
P-phyll. In the case of two flowers, they can be either, 1) the product of the axillary 
meristem in the a-phyll and the transformation of the remaining modular meristem 
or 2) both can be the product of the modular meristem with little or no evidence of 
an a-phyll. In the one-flowered systems, the flower appeared to be the sole product 
of the axillary meristem in the bract axil, although in some, an a-phyll was initiated. 
In most cases, the initiation of the first floral organ followed the previously established 
phyllotactic pattern of the subunit (2/5) although there is a shift in divergence angle 
with successive floral primordia to a 1/4 pattern. In the single flowered systems 
with a subtending bract only, the sequential initiation of tepals is similar to most 
other Proteaceae with the frontal or transverse tepal pair arising first. Weberling 
(1989; Eichler 1875/1878) termed this pattern as 'eprophyllate aestivation'; that is, 
the first two floral organs to develop are positioned as if they were prophylls (two 
in dicots, one in monocots; Weberling 1989). A developmental presumption in 
eprophyllate aestivation patterns is that the position at initiation of the first two 
primordia of a flower is influenced by the position of the preceding organ(s), or that 
the sequential initiation of an organ from a meristem is influenced by the position of 
the preceding organ (Hofmeister in Weberling 1989; Eichler 1875-8; termed 
phyllotactic continuity within a flower by Posluszny 1993). In the case of single 
flowers in bract axils of Carnarvonia and most other Proteaceae, the organ subtending 
the flower appears to influence the subsequent initiation of the first floral organs; 
therefore a more appropriate term would be eprophyllate initiation (Douglas 1994; 
Douglas & Tucker 1996a, b, in press). In taxa with a single flower borne in a leaf axil, 
the first two organs to be initiated are generally in lateral positions, analogous to 
prophylls on a vegetative meristem (e.g. Drimijs lanceolata Tucker 1959; Psenciowintera 
traversii Sampson & Kaplan 1970; Sanguinaria Lehmann & Sattler 1993). Similarly, the 
initiation of the first two floral organs in lateral positions is found in taxa with 
flowers that develop in bract axils on blastotelic inflorescences: (e.g. Papaverales 
Sattler 1973, Karrer 1991; some flowers of Scrophulariaceae Weber 1973; Armstrong 
& Douglas 1989; Liquidambar styraciflua Wisniewski & Bogle 1982; Potamogetonaceae 
Posluszny 1993; also see Douglas and Tucker 1996a for additional examples). 
