Bernhardt & Weston, The pollination ecology of Persoonia 
797 
morphology of the perianth of a Persoonia flower resembles that of bilaterally 
symmetrical flowers of Lamiaceae and Scrophulariaceae where insects must depress 
the outer lobes of the corolla to gain access to nectar concealed at the base of a floral 
throat or spur (Faegri and van der Fiji 1979; Barth 1985). Therefore, a short-tongue 
colletid exceeding 9 mm appears to be as efficient a vector of Persoonia pollen as a 
long-tongue anthophorid with a mean body length of 7 mm or less. Both forage 
actively for pollen. Both are sufficiently dexterous, heavy and long enough to depress 
the tepals and then gather nectar from the base of the flower. 
Consequently, floral presentation in Persoonia must exclude as dependable pollinators 
most of the smallest bees such as Trigona carbonaria and Leioproctiis (Filiglossa) species. 
Their mouthparts reach the nectar chamber of most Persoonia species and contact the 
anthers while foraging. However, the bodies of these insects are too small to regularly 
contact the stigmas while foraging for pollen and/or nectar, despite their high density 
and repeated visitations of flowers in some Persoonia populations. Cross-pollination 
by Trigona may be confounded further by the presence of corbiculae and pollen 
pellets as described, above, in A. mellifera (Michener 1974). 
On the other hand, while an increase in physical size ensures a native insect's access 
to the nectar chamber, encouraging passive contact with the stigma, it does not 
guarantee that the same insect will always transport loads of Persoonia pollen. 
Although Amegilla, Chalicodoma species, and some wasps are longer than Exoneiira 
and Leioproctiis {Cladocerapis) species by 3-4 mm, they appear to be inferior pollen 
vectors. These larger native hymenopterans contact stigmas while depressing the 
tepals but they were not observed to forage actively for pollen on Persoonia anthers. 
Their pollen load analyses showed they acquire little pollen while collecting nectar. 
Therefore, while tube length varies greatly between Persoonia species of eastern Australia 
there is little evidence of a correlation between the physical length of the floral tube 
and the body length or tongue length of its true pollinators. Based on measurements 
of the three to four, native taxa of common pollen vectors the differing lengths of floral 
tubes betw'een Persoonia species does not appear to have encouraged the segregation 
of different pollinator species to different Persoonia species in eastern Australia. Since 
access to nectar is based on the physical strength and foraging behaviour of the bee a 
correlation between the actual length of the hinged tepals Persoonia species and the 
length of their pollinators' probosces should not be anticipated. 
Perhaps both the sheer length and/or degree of constriction of the tepals around the 
nectar chamber helps to restrict the loss of nectar reserves to smaller thieves. Filiglossa 
and Trigona species have long mouthparts for their small size. Directional selection 
may have favoured increased tepal length where nectar thieves occur at higher 
densities. For example, the flower of Persoonia arborea has the longest floral tube and 
its exposed ovary forms a cap over the narrowed, nectar chamber. Persoonia arborea 
grows in an area where it is visited by swarms of Leioproctiis {Filiglossa) davisi 
(K. Walker, personal communication). These bees don't contact the flower's stigma 
and are shown to be poor, pollen vectors in this study. In Persoonia pinifolia the long 
tepals appear tightly wrapped around the style above the pouched, nectar chamber. 
Trigona carbonaria is the most commonly collected and observed visitor on flowers of 
the P. pinifolia population in this study. 
This is the first study to compare the pollen carrying capacity of male and female bees. 
While most males in the subgenus Cladocerapis fail to carry heavier loads than females, 
85% of these males carry from 25 to >100 grains of Persoonia pollen although none 
forage actively for pollen. Cladocerapis males then are actually superior vectors of 
Persoonia pollen than nectar foraging females of Amegilla and Chalicodoma species. This 
also suggests that, at certain sites, Cladocerapis males are probably far more important 
