Douglas, Inflorescence development in Carnarvonia 
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A contrasting order of initiation is seen in taxa that have bracteoles (prophyllate 
aestivation semu Weberling, 1989). The first floral organ (or first two floral organs in 
some four-merous taxa) is initiated on the side furthest from the axis and in a plane 
perpendicular to the transverse or frontal plane in numerous Leguminosae (Tucker 
1984, 1987a, 1987b, 1992, Tucker & Stirton 1991); Juglandaceae, Myricaceae, Fagaceae 
(MacDonald 1971; Saltier 1973; Abbe 1974); Arecaceae (Uhl 1988), and Onagraceae 
(Saltier 1973). 
In Carnarvonia, the sequence of initiation of the tepals, particularly the terminal 
flowers of a determinate subunit, appear to be directly influenced by the preexisting 
organs of a subunit. In the cases where there is no observable subtending bract to 
the terminal flower, the first tepal is initiated in a site continuous with the established 
phyllotactic sequence of the subunit. Phyllotactically continuous patterns of perianth 
initiation (phyllotactic continuity) have been found in flowers of anthotelic axes of 
some Ranunculaceae (Wydler 1872), Linaceae (Bravais & Bravais 1837) and 
Alismataceae (Charlton 1973, 1981). 
In Carnarvonia, the carpel is initiated and positioned in a site that is phyllotactically 
continuous with the preceding primordia of the flower. In most proteaceous taxa, 
after stamen initiation, the remaining floral apex enlarges throughout and is fully 
converted to a carpel primordium (Douglas 1994; Douglas & Tucker 1996b, in press). 
In Carnarvonia, the carpel primordium is initiated towards one side, the dorsal side 
of the carpel being next to the first tepal and stamen that were initiated. A long¬ 
standing controversy in flower evolution is whether the single carpel is a terminal or 
lateral structure (Newman 1936a, b; Thompson 1936 a, b; Brooks 1940; Tucker & 
Gifford 1966). Considering the well-supported hypothesis that the carpel is a leaf 
homologue (Goethe 1790; although see Meeuse 1963, 1965, 1966 for an alternate 
opinion), one would expect to find vestigial evidence of the floral residuum in 
single-carpellate taxa, particularly if the carpel is a lateral organ (Newman 1936a,b). 
Apical residuum in unicarpellate flowers is rare and is not present in Carnarvonia. 
The phyllotactic continuity of the flower organs through the carpel stage can be 
considered a general developmental condition where the sites of sequential initiation 
of primordia from the meristem perseveres. Deviations from a pattern of phyllotactic 
continuity can be considered a developmentally derived condition. 
Architectural/physiological constraints 
The mature inflorescence architecture is loosely constrained in Carnarvonia, although 
from a developmental perspective at the level of the axillary meristem and its 
products, the inflorescence architecture is conserved. In most plant systems, it has 
been hypothesized that there are canalised ontogenetic events that maintain a taxon 
specific morphology or architecture (conservation of organization, Waddington 1962). 
It has also been hypothesized that in an ontogenetic pathway, alterations in early 
ontogeny result in the macroevolutionary differences among taxa. On the other hand, 
changes that occur later in an ontogeny tend to be significant to microevolutionary 
patterns of morphological differences among taxa (Tucker 1984,1988). Unfortunately, 
most of the studies of developmental canalization and ontogenetic constraint models 
focus on features in the flowers and not the inflorescences. 
Conservation of organization is apparent in inflorescence architectures among taxa, 
particularly when one considers the fact that an inflorescence is the reproductive 
equivalent of a branching system as proposed by Linnaeus (1751; Rickett 1944) and as 
a branching system, it is made up of metamers that combine to define a module or 
subunit (White 1979,1984). Barlow (1989) defines a hierarchical basis of morphological 
organization, each hierarchy of which combines its individual elements to make up 
