Main Club, 4 October 2024
Greg Keighery was our speaker, a botanist and well-known Club member. Since 2003, Greg has been a Senior Principal Research Scientist with The Department of Biodiversity, Conservation and Attractions (DBCA). He talked about the genus Verticordia, which means “turner of hearts” and refers to Venus because of its beauty.
Greg discussed the current difficulties in classifying the species belonging to the Chamelaucium alliance, which is a sub-group of the family Myrtaceae and includes Verticordia (the Featherflower), Chamelaucium (the Waxes), Calytrix (the Star flowers), Pileanthus (the Coppercups) and Darwinia. All the plants in this group have secondary pollen presentation – a mechanism in which the pollen, in the bud stage, is suspended in an oily fluid and sticks to hairs on the style close to the stigma to present it to pollinators.
It seems that Verticordia is not a natural genus, and neither is Darwinia. We are used to using the name Verticordia for all the Featherflowers – those beautiful flowers whose sepals and sometimes petals are divided (feathery).
But we may soon see a name-change in the light of genetic and anatomical studies (e.g. a number of chromosomes and a number of ovules), which show that these groupings do not reflect their evolutionary relationships. Those feathery sepals may have evolved independently a number of times.
This research may result in the Verticordia in WA being split into four separate genera. Another benefit of knowing the number of chromosomes is that it can help develop artificial hybrids for horticulture. The fact that Verticordia plumosa and Chamelaucium uncinatum can be hybridised illustrates how close these genera are.
The genus Darwinia is named after Erasmus Darwin, a polymath and a very interesting man who was the grandfather of the famous Charles. Significant differences exist between the Darwinia of the eastern states and those of WA, so this genus will have to be split and renamed. But the genera Pileanthus and Chamelaucium will be retained.
Greg pointed out that genera do not evolve; populations and species evolve, but genera are artificial constructs. He said that to preserve the species we need to know such things as their response to fire, their longevity, their pollination mechanisms, the taxonomic rank of species and varieties, the status of populations and conservation status of the species. The Chamelaucium alliance has a wide range of shapes and colours, depending on their pollinators. Some show a colour change to “switch off” from pollinator attractiveness after they have been pollinated. Some pollinator relationships are very specific, such as Verticordia nitens (a species killed by fire) having their own bee, the plant and the insect being mutually dependent. The large red flowers of V. grandis are among the bird-pollinated species. There is much more to know about the pollination mechanisms of these plants.
Mike Gregson