Research on Golden Grevillea

Research into the Golden Grevillea (Grevillea chrysophaea) – ongoing in the Brisbane Ranges

Julie Atkinson, PhD candidate (and FoBR member), Department of Botany, La Trobe University

Most of you will be familiar with the Golden Grevillea (Grevillea chrysophaea) that occurs in the Brisbane Ranges – especially in the Steiglitz area. From a biogeographic perspective, this species has a fascinating distribution. In addition to the Brisbane Ranges, it is also found in central Gippsland (south-west of Sale) and in the foothills of the Alps (up near Heyfield and Licola).

Peter Olde and Neil Marriott, who wrote The Grevillea Book in 1995, recognise three forms of the Golden Grevillea – corresponding with the three areas it occurs in. It seems impossible that they could be linked by gene flow – as they are likely pollinated by honeyeaters (or maybe insects), which are not known to travel long distances, and seed dispersal is fairly passive (seeds are propelled from the parent plant when seed pods open). One would certainly expect some differences to have evolved in the time these populations have been separated. How could the same species occur in such different habitats across such vast differences?

Those were some of the questions that I attempted to answer in my honours research year at La Trobe University 2009-2010. I looked at genetic structuring between populations of G. chrysophaea, leaf and growing habit variation (unfortunately flowers were left out of the analyses due to the time limitations of my study) and very briefly at habitat differences. Honours year is the first opportunity for students to conduct their own independent research projects and often the results are not terribly robust, as was the case with my project.

My results indicated little genetic structuring, with the exception of two populations that were unique when compared with all other populations. Leaf and growing habit indicated some variation between forms with Brisbane Ranges plants being intermediate between the two Gippsland forms. Habitat comparisons confirmed that the habitats these plants occur in are vastly different, as the location records for one form could not predict the distributions of the other forms.

Although disappointed not to get the results I had hoped for, I decided to continue my research into Victorian Grevilleas for my PhD. This time, I am focusing on three species: Cat’s Claws Grevillea (G. alpina), Nowa Nowa Grevillea (G. celata) and, of course, Golden Grevillea (G. chrysophaea). These three species are closely related – but also have interesting differences. 

G. alpina is widespread in Victoria, occurring from the Grampians right up to Beechworth and beyond. However, within this distribution, there is significant variation within the species – especially in growing habit, leaf form, floral colour and floral size. This species could represent a case of evolution-in-action – with current day forms representing future species.

Contrasting with both the widespread G. alpina and the disjunct G. chrysophaea, the Nowa Nowa Grevillea (G. celata) is a narrow endemic, occurring only in the Colquhoun State Forest east of Bairnsdale. This species is considered rare and threatened, due to its narrow distribution. Perhaps surprisingly, considering its geographic distribution, it may have originated from a hybrid speciation event between G. alpina and G. chrysophaea – it certainly appears intermediate between the species in many ways: the foliage very closely resembles that of G. chrysophaea whilst the floral colour is similar to that of G. alpina.

I am curious about the evolutionary processes that have contributed to the divergence of these three species – how did they become different? And what are the evolutionary processes acting upon them today – what will they become?

I am approaching these questions by using a number of different techniques:

  • Next-Generation Sequencing: are there genetic patterns between forms and species?
  • Pollinator identity: are they pollinated by the same species?
  • Floral colour: how do colours differ between forms?
  • Nectar traits: do different forms produce different quantities or qualities of nectar?
  • Phenology: do they flower at different times of the year?
  • Pollination experiments: is it possible to cross-breed different forms? Are they self-compatible?
  • Floral morphology: are the flowers the same shape and size? How does this compare with pollinator traits, such as bee body size and bird beak length?

The Friends of Brisbane Ranges has kindly donated two plants of G. chrysophaea to my research. These plants will be used in the cross-pollination experiments.

In addition to answering academic questions of evolution, adaptation and divergence, I am also interested in the implications of my research on the management of these species. Of particular concern are the futures of G. chrysophaea and G. celata as they are both rare.

When considered separately, two of the G. chrysophaea forms have very narrow distributions – much reduced from historic records.

The Brisbane Ranges form now seems to be limited to the Steiglitz area, and mostly to roadside (if anyone has information about natural populations away from Steiglitz, please contact me). It is also hybridising with at least two non-indigenous species: G. lanigera in the Steiglitz cemetery and G. rosmarinifolia on Butchers Rd and Switch Rd – which in such a narrowly distributed taxon, may threaten its genetic integrity and identity.

The Holey Plains form of G. chrysophaea, which occurs southwest of Sale, is also very narrowly distributed. Much of its former range is now taken up by pine plantations. During my research, I have only managed to find two populations of a decent size, one of which is regularly slashed. Ironically, the slashing may be what is allowing this species to persist – as it is not found adjacent to the slashing sites.

If you are interested in my research – you can help! I am not able to get out ‘in the field’ as often as I would like and so can always use some ‘eyes on the ground’. In particular, I am interested in:

·       Phenology – If you commonly encounter a population of Golden Grevillea you can let me know when they start flowering, when their flowering is at its peak, and when the last few flowers die off (stop flowering). Please include their approximate location and photos of a plant and a flower would also be beneficial, but not necessary

·       Pollinator Observations – If you observe an animal visiting a G. chrysophaea flower, I would like to know the identity of all potential pollinators. The name of the bird, insect or mammal would be useful but a photo, video or even a specimen (for insects) would be very valuable!

·       Population locations – as I indicated above, I am only aware of decent sized populations of G. chrysophaea near Steiglitz. If you know of any, or discover any, decent sized populations (>30 individuals) away from Steiglitz (in the Brisbane Ranges proper, or in the You Yangs etc.) please let me know.

My email address is: This email address is being protected from spambots. You need JavaScript enabled to view it.

If you would like more information about my research group, please visit the La Trobe University Molecular Biodiversity blog at: http://molecularbiodiversity.wordpress.com/

I also run another blog for the Australian Plants Society, Maroondah group that you can visit at: http://greenfingersaps.wordpress.com/