Grevillea williamsonii; Clinging to Survival

Neil Marriott

In 1893, H.B. Williamson discovered a solitary Grevillea at the foot of a small hill between Mt Abrupt and Mt Sturgeon, at the southern extremity of the Grampians/Gariwerd Ranges in Western Victoria. This was described by von Mueller in December of that year as Grevillea williamsonii, the description of which was published in the Victorian Naturalist Vol.10.:129.

This area of the Grampians was burnt out by a bushfire four years later, in 1897 and the sole G. williamsonii was destroyed. Subsequent searches (often quite thorough and extensive) by botanists and naturalists, failed to relocate the species, and after some 90 years, the species was presumed extinct. In "A Handbook to Plants in Victoria - Vol II" written in 1972, Jim Willis states that "affinities are with G.aquifolium" and it is possible that G.williamsonii was a mutant of this species or part of a hybrid population.

Several years ago, further doubt was thrown on the validity of G.williamsonii as a species, when steam softened specimens housed at the Melbourne Herbarium were found to be sterile. It was determined that the lone plant was merely a "putative hybrid..." probably with G.aquifolium" as one of the parents.

In 1992, Brian Lacy, a native plant enthusiast from the southern Grampians told me that a friend of his had discovered a population of unusual Grevilleas with toothbrush flowers in the local bush. Entire-leaf forms of G.aquifolium are not uncommon in the Grampians, and although I briefly considered G.williamsonii, I dismissed the idea, preferring to see a specimen of the plant first.

In November 1992, Betty Lacy brought me some flowering specimens, and I couldn't believe my eyes, having seen the original specimens of G.williamsonii in the Melbourne Herbarium. I recognised the fresh specimens as being almost certainly that species. As I was going to the Herbarium the next day to complete some work on new species for the "Grevillea Book", I took the opportunity to carry out microscopic comparisons between H.B Williamson's collection and the fresh specimens. There was no doubt, G.williamsonii had been rediscovered!

The inflorescence of Grevillea williamsonii has flowers arranged in short "toothbrush-like" clusters. Select the thumbnail image or plant name for a higher resolution image (36k)
Photo: Neil Marriott.

Dave and Lyn Munro sensed they had discovered something different when they stumbled on the small colony of unusual Grevilleas whilst looking at orchids. They were absolutely thrilled to find out the plants were the presumed extinct G.williamsonii. The site was in the bush some 7 kilometres north of Piccaninny Hill, where Williamson discovered his Grevillea nearly 100 years ago.

Arrangements were made to visit the site, and we marvelled at the luck of the Munro's discovery. The Grevilleas are not visible from the track and searching the area failed to reveal any more plants. The colony consists of 5 mature plants and 7 smaller specimens. Mature plants were dense shrubs 1 m x 1 m with a distinct horizontal layering habit with ashy, grey-green foliage and masses of small yellow toothbrush flowers which age to pink. One shrub was greener with occasionally toothed leaves but similar flowers. Examination of the flowers showed the species to be actually closer to G.ilicifolia than G.aquifolium.

I was most interested to note on a subsequent visit that several of the larger bushes had immature follicles (seed pods) developing, despite the fact that the flowers we had dissected had no anthers and hence no pollen. This tied in with the earlier findings of sterility in Williamson's plant. A number of young follicles ware bagged, resulting in the subsequent collection of five well developed viable seeds several weeks later. Possible explanations of this surprising outcome could be that the species has very few fertile flowers, the majority being sterile or early season flowers may be fertile with end of season flowers being sterile. A further explanation could be that the flowers are self pollinated while in bud, with anthers being shed at antithesis. Further research will eventually reveal the truth to this fascinating puzzle.

A small amount of cutting material was collected with half being sent to Mt Annan Botanical Gardens. Material has struck well and has been potted on. Due to the rarity of the species, no further collections will be made from the wild.

The Society for Growing Australian Plants