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Telopea Vol. 6(4): 1996 
width corresponding to the hypanthium, but the petals maintain a narrow zone of 
insertion on the hypanthial rim. The fascicle of stamens resulting from each pre- 
staminal bulge remains in its antepetalous position, also with a narrow area of 
insertion; as a consequence the individual fascicles are distantly separated in the 
mature flower (Fig. 22). The fact that individual stamens remain so tightly clustered, 
and do not disperse at all with hypanthial expansion, indicates that the stamens are 
subordinate to the pre-staminal bulge, not to the receptacle of the flower. A similar 
pattern occurs in ]Nelchiodcndron (Fig. 9). 
In Tristaniopsis lauriiia (Fig. 11) the pre-staminal bulges are only just apparent prior 
to stamen primordia initiation; in fact the whole flower is less developed than at the 
same stage in L. confertus and the petals are also correspondingly smaller. This lesser 
independent development of the pre-staminal bulge correlates with almost no 'fusion' 
of stamen filaments in the fascicle, but the fascicles still manifest as discrete units 
that maintain their restricted area of insertion in the antepetalous regions, each 
fascicle widely separated from the others in the fully expanded flower. 
No pre-staminal bulge develops prior to inception of individual stamen primordia in 
Xanthostemon and Lysicarpiis (Figs 12-16). Instead, two to several stamen primordia 
form directly on the flank of the apex in positions more or less in front of each petal. 
The concavity of the apex and the separation of adjacent petals combine to give the 
impression that the stamen primordia, like the pre-staminal bulge in Lophostemon, form 
directly on the petal primordia, but there is nothing in the subsequent development of 
either stamens or petals to suggest they are in any way morphogenetically linked. 
Subsequent primordia fill in the rest of the concave apex laterally and radially but the 
grouped appearance remains clearly visible. In X. oppositifolius, they appear superficially 
to be in triangular, antepetalous groups up to four stamens wide and four tiers deep, 
but this is an illusion caused largely by the shape of the apex. The cone shape of the 
inverted apex allows more primordia around the circumference at the top (nearest the 
petals) than at the bottom (nearest the centre) and this, together with the location of the 
oldest stamens of each tier in the centres of the antepetalous areas, accentuates the 
clustering of stamens (Fig. 23a-c). In fact, the stamens form evenly over the ring-shaped 
flank of the invaginated apex, which acts a single, continuous, phyllotactic zone. 
Enlargement of the flower subsequent to organ inception, like Lophostemon, occurs 
largely by expansion in the antesepalous regions; sepal bases expand correspondingly, 
but the petals remain attached narrowly. The few stamens in the static zone 
immediately in front of each petal maintain their position relative to the petal and to 
each other, resulting in an apparent 'group' two to several stamens deep. The rest 
are displaced from their multi-tiered positions by expansion of the flower, and more 
or less evenly spaced out in a single row around the entire rim of the hypanthium 
(Fig. 23d,e). This secondary relocation of the stamens is a stark contrast to the 
determinate fascicles of Lophostemon, Welchiodendron and Tristaniopsis, and indicates 
that the stamens of Xanthostemon and Lysicarpiis are subordinate to the hypanthium 
or floral axis, and that there is no intervening morphological structure. 
Metrosideros collina and Tristania neriifolia (Figs 17-20) have far fewer stamen primordia 
and not nearly as great an expansion of the hypanthium; these features combine to 
make their interpretation ec^uivocal. Metrosideros collina shows a hint of pre-staminal 
bulges, but only one row of stamens forms around the flower. These stamens are 
spread evenly around the hypanthium at anthesis, but flower expansion is not 
sufficient to widely space the filaments to allow consideration of the similarity 
between antepetalous and antesepalous regions. Occasionally there is a small gap 
opposite a sepal, and sometimes two adjacent stamen primordia become continuous 
and grow as a single, thick filament, but there is no consistent pattern of clustering, 
and there is no obvious filament base fusion typical of fascicled taxa. 
