Could diaries, newspaper clippings, and letters be hidden at the Arnold Arboretum, unexamined for almost one hundred years? Might the Arboretum possess more than two hundred glass plate negatives by famed plant collector Ernest Henry Wilson without labels for location or species? In the spring of 2016, I met Arboretum scientist Peter Del Tredici while visiting MIT, and he invited me to see the Arboretum, an invitation I accepted with relish. After a tour of the grounds, including a walk in the woods, a stop on Peters Hill, a discussion of insect attack on hemlocks, and a look at the amazing old bonsai, we found ourselves in the horticultural library. “Bet you Australians don’t know that Wilson went to Australia in the 1920s,” Peter said. “No one has looked at the collection. It’s sitting there.” He pointed, and there it was, hidden in plain sight.

When I returned to Australia, I inquired as to whether, indeed, botanists knew that Wilson, famed for botanical explorations in China, had travelled to Australia. No one did. Everyone that I spoke with was astounded. Herbaria staff did not know; botanists at my university and elsewhere did not know; even those who have a long and keen interest in the botanical exploration of the Australian continent did not know.

Wilson’s expedition between 1920 and 1922 was to Commonwealth countries and no others. During my time in the United States, I have been asked, on a number of occasions, what the Commonwealth is, what countries belong to it, and what it means. The Commonwealth consists of now-independent countries that once made up the British Empire, and these countries are joined by commonalities, such as a politically independent judiciary and public service, school uniforms, and cricket, the second-most popular sport in the world after soccer. Wilson’s travels took him to countries now known as Australia, New Zealand, Malaysia, Singapore, India, Sri Lanka, Kenya, Uganda, Zimbabwe, Zambia, and South Africa, before returning to England and then on to Boston.

He wrote about the horticultural aspects of this trip in various garden magazines, as well as in the first volume of his book Plant Hunting, published in 1927 (and reprinted decades later as Smoke that Thunders). The writing in the book is part tourist travelogue and part horticultural journal, with a discussion of the cultural requirements and garden potential of plants met along the route. What surprised me was how much Wilson knew about the discovery of the western coast of Australia by the Dutch in the early 1600s, sailing eastwards from Cape Town to use a faster route to the East Indies. This is a lesser-known history than that of Captain James Cook mapping the east coast of Australia in the 1770s, and it shows that Wilson was remarkably well-informed in 1920.

Two years after learning about Wilson’s expedition, I returned to the Arboretum with a Sargent Award for Visiting Scholars, intent on examining the archives, images, and herbarium specimens pertaining to Wilson’s time in Australia. I was fascinated by the idea of a lost collection of Australia and, like many botanists, interested in the history of plant collecting. I was also curious as to whether the images might offer a glimpse of land now lost to agriculture and suburban development, both research areas of my own. What I found in the archives was a collection in excellent order, with annotated boxes, carefully arranged glass plate negatives that had been digitized in 2018, meticulously kept diaries with their labels and individual folders in boxes, and neatly ordered newspaper clippings, letters, and ephemera of the expedition. I took photos of every box and every label. It was not evident who had established the organization of the collection, but even with the clear organization, there was little documentation to suggest what was in the letters, or what the images showed and where they were taken. While images from India and Africa were annotated with old typewriter notes on thin white paper, the Australian images—numerically numbered and coded with the letter Y—were not annotated, and it was unclear just where Australia started and ended.

It became clear to me that my inquiry would require three components: The examination and transcription of diaries, letters, and notes; the annotation of the unlabelled images; and a search of the Arnold Arboretum Herbarium to see what plant specimens had been submitted there by Wilson’s expedition.

Wilson arrived in the port of Fremantle, on Australia’s western coast, after a tedious and hot trip by boat from Sri Lanka (then Ceylon). He was immediately struck by how Perth, the capital of Western Australia, reminded him of southern California. (There is a saying in Perth, my hometown, that we have the climate that the Californians think they have.) Southwestern Australia has, like southern California, hot summers and mild winters, and this was important to Wilson because Henry Huntington, a sponsor of the expedition, was eager to hear of plants suitable for cultivation in California. This region, today referred to botanically as the Southwest Australian Floristic Region, is known for its exceptionally high levels of floral endemism—meaning plant species that are found nowhere else in the world. Wilson was astounded by the plants he found there. “To a visitor from the Northern Hemisphere, no matter how familiar he or she may be with the forest scenery of the North, Western Australia is a new world,” he wrote in Plant Hunting. “Nay, it might well be part of another planet so utterly different is the whole aspect of its vegetation. Intimate knowledge of the plants of the boreal regions only serves to accentuate the variance.”i

Black-and-white photograph of man standing beneath large tree
Charles Lane-Poole—formerly unidentified in Wilson’s collection of glass plate negatives—stands beside a massive eucalyptus. In a letter to the Arboretum, Wilson mentioned that, soon after arriving in Australia, Lane-Poole “became guide, philosopher & friend.” Arnold Arboretum Archives

While reading Wilson’s thoughts on the Australian flora, I was struck by his observational clarity, especially after recently reading a paper on the evolutionary history of the Australian flora over the last sixty-five million years. “To what extent is the Australian flora unique?” the authors—botanists Michael Crisp and Lyn Cook—asked, perhaps asking because most Australians think it is and most foreigners agree with them. They noted that thickened foliage (sclerophylly) is not unique to Australia, nor are traits that promote water storage (xeromorphy), nor is fire as a selective genetic force unique to the continent. But nowhere else do these combined traits dominate large proportions of an entire continent.ii

Wilson, however, immediately noted two traits as completely unique to Australia: the angle of leaf repose and the color of the flora. “In the North our trees in general have spreading umbrageous crowns, dark, often lustrous green leaves which … cast a heavy shadow,” Wilson wrote. “In Western Australia the dominant trees have open, tufted crowns, gray or glaucous green leaves which … cast little or no shadow. This difference in the color of the tree-foliage and the fact that the leaves are pendant instead of spreading on the branches may seem to the reader trivial matters, but in reality they completely change the aspect of the forests and profoundly influence the whole landscape.”iii To have quickly put his finger on these two points is a tremendous perception. The color of the Australian flora presents a world of very different greens and grays to the Northern Hemisphere, as I have found in my own research, and Wilson appeared to have recorded them all.

The unique flora of Australia made it relatively easy for me to tease out Australian images from the others. I also began to identify the unnamed individuals in the photographs. One man, who recurred in multiple photographs, was distinctive due to a hook in place of his left hand. I emailed Australian colleagues about a botanist matching this description (which I thought would have been easy), but I met a blank. Eventually, I came across a biographical entry about Charles Lane-Poole, the conservator of forests in Western Australia from 1916 to 1922, which mentioned that his left hand had been lost in a shooting accident when he was nineteen (all other biographical sketches politely did not mention this). I had my man.

I later came across Wilson’s comment that he had travelled two thousand miles with Lane-Poole “through all the important forest areas.” Elsewhere, in “the sand plains and savannah regions,” he was guided by Desmond Herbert, the Western Australian government botanist, who was also shown in images. Wilson noted that, without such expert guides, “I should have been completely lost among the extraordinary varied and anomalous vegetation.” These men were top in their field and their companionship and assistance shows the esteem in which Wilson and the Arnold Arboretum were held. The images, however, revealed an oddity—all that I could readily identify were from the beginning of his trip in Western Australia.

With limited time, I set to work, realizing that diaries could be transcribed, letters read, and images annotated in Australia. Thus, I headed to the Harvard University Herbaria, where the Arboretum Arboretum’s wild-collected herbarium specimens are housed, because I recognized that those materials could not be examined later. While Wilson’s notebooks and photographs would provide some sense of his route across the continent, the specimens in the herbarium would provide more detailed information about where and when Wilson travelled, what he was collecting, and the identities of other botanists who collected on behalf of the Arboretum.

At the Harvard University Herbaria on Divinity Avenue, I was given pencils, little paper envelopes for broken off bits of specimens, and clear plastic clips to replace rusty metal clips from one hundred years ago. The collection is contained within rolling cabinets, called compactors, and I was presented with a written directive that “compactors can be opened by releasing the locking bar and smoothly rotating the handle of the appropriate bay.” The instructions also suggested to “move one row at a time to prevent strain on the system,” although I was not sure whether that was referring to the compactors or to me. Lists of plant families hung on the walls, indicating where the families were housed in the building’s several floors and annex rooms. “Where would you like to start?” Anthony Brach of the herbaria’s curatorial team asked me. I looked about wide-eyed. Well, why not Myrtaceae? I ventured, and Anthony chuckled. I had chosen “the big one”—the family of the eucalypts.

Herbarium specimen
Herbarium specimen
Herbarium specimen

Eucalyptus is a major genus in Australia and is rare in the world in that this single genus virtually defines an entire continent. There are now over eight hundred species (the number always rising), and this usually surprises overseas visitors to Australia, who often think that there are only a few “gum trees.” The eucalypts include the world’s tallest flowering plant, E. regnans, known as the mountain ash, which reaches heights of 295 feet (90 meters). Timber records in the nineteenth century reported that trees logged then had reached far greater heights—up to 490 feet (150 meters). This loss underscores one of the reasons Wilson was keen to see the Australian forests.

Eucalypts, however, are not all tall; some are small and gnarled; many are low shrubs and suitable for home gardens; some have brilliant flowers; some have dusky gray leaves that are suitable for the flower trade; some possess huge bud caps that gave the genus its name—eu (well) and kalyptos (covered); some are small and gnarled; some are single-trunked; others have a mallee form, an Aboriginal term referring to plants with multiple trunks that emerge from underground lignotubers. Most live in mixed woodlands. Wilson was captivated by their variety and the colors and forms of trunks. He noted, for example, that the salmon gum (Eucalyptus salmonophloia) “is a handsome tree, with a smooth white to pinkish trunk … the twigs are reddish” and that the gimlet (E. salubris) is “fluted and twisted like a screw—hence the name gimlet.”iv In photographs, he recorded fire-scarred trees, and he was clearly impressed by the extraordinary capacity of most eucalypt species to resprout after fire.

During the next few weeks, I extracted hundreds of specimens from the expedition across a large range of families and genera, all from blue folders that indicated the specimens came from Australia. These were easy to spot among swathes of green, orange, pale orange, yellow, pale yellow, beige, white, off white, and ranges of pinks and reds. In short, if a folder was blue, I knew it was mine to take out and examine. How curious and exciting it was to search through the blue folders and find labels with Wilson’s name and handwriting. “Near a saltlake,” he noted on one. “In a group of trees,” he wrote on others. He described a now-rare little shrub (Daviesia euphorbioides) as a “centipede bush” and called a large shrub (Banksia sessilis) “parrot bush.” Many labels included collection numbers that related to the diaries.

Map of Wilson's travels in southwestern Australia
Locations recorded on Wilson’s herbarium specimens and in notebooks revealed extensive collections throughout southwestern Australia, from the towering karri (Eucalyptus diversicolor) forests, south of Perth, to the semi-desert forests farther east. Contemporary train lines are shown in gray. The Trans-Australian Railway, completed in 1917, connected Kalgoorlie with eastern cities. Arnold Arboretum and GIS Community

From the images, I knew that Wilson and his travel companions appeared to have gone by horse, train, and a roofless Model T Ford. They travelled south of Perth through wetlands near Busselton, into the Darling Scarp—the hills east of Perth—to collect in the jarrah (Eucalyptus marginata) forest. They continued south to the tall karri (E. diversicolor) forests, east through heavily cleared land of wheat and sheep fields, and still farther east into semi-arid country. Labels in the herbarium revealed place names: Yoting, Burracoppin, Merredin, Toodyay, Widgiemooltha, Quairading, Coolgardie, and Kalgoorlie. Many of these are indigenous names given to country towns or settlements that in 1920 and 1921 were gold-mining camps. At one such now-tiny outpost, Westonia, Wilson noted in his diary on October 22, 1920, that “Saturday night in a mining camp is not a quiet place. Singing and chat extended far into the night.” Looking at the labels in the herbarium, I was amazed to see where Wilson went—to places remote enough now, let alone then. A whole suite of specimens was collected “20 miles south of Coolgardie,” in hot and dusty conditions, but Wilson enthused over the “astonishing” variety of species. In his diary, he wrote, “they are mostly prickly in character and many of them especially so.”v

Reviewing the specimens belonging to the Proteaceae was a treat for me because my doctoral dissertation had been on the ecophysiology of Banksia, which is the most well-loved member of the family in Australia. As I opened the compactors, I could see the banksias in their blue folders, and I laughed—they were large, chunky folders. Banksia flowers grow in hairy cone-shaped inflorescences, which measure up to seventeen inches long. Some of the cones—the flower heads or remaining fruiting bodies—were stored elsewhere, in boxes, due to their size, and Anthony Brach got them out for me. These attracted comment from passing taxonomists in the herbarium, but I pitied that they could not see them on the trees instead of these dead, dry relics. One even commented: “How wonderful to work on these. Some people,” she shuddered, “have to work on grasses!”

Wilson collected various banksia species near Perth and inland, and many of his images are of banksia trees. As I pulled out specimens, I mused as to what Wilson must have thought about when he looked at the banksias, with their wire-tough thick leaves, erect demeanour, and vibrantly colored inflorescences, usually buzzing with insects and birds with tongues and beaks evolved to suck nectar from these exact trees. In Plant Hunting, he described the genus as “among the most wonderful flowering trees of Australia.” He described the large pale lemon and yellow flowers of Banksia grandis, with cones measuring up to eight inches long, and he noted elsewhere that the species should be grown in California.

Beyond the visual appeal, many contemporary botanists were intrigued by the banksias—which are particularly prominent in southwestern Australia—because these were clearly related to the striking diversity of Protea from South Africa. Our contemporary understanding of continental drift was first proposed by the German scientist Alfred Wegener in 1912, and we now know that Antarctica, Australia, South America, Africa, India, and New Zealand were once joined in the supercontinent Gondwana and shared flora. Proteaceae is one of the oldest families in the Southern Hemisphere and once was found across Gondwana, right across what is now Antarctica. Fifty-million-year-old fossils have been found in Patagonia and New Zealand that even an untrained eye would easily recognize as lovely banksias. But alas, as Wilson knew, none of these living beauties would grow in Boston’s climate for the Arboretum.

As my notes from the herbarium accumulated, I soon realized that, as with the photographs, the specimens were almost entirely collected in Western Australia. This was odd, as Wilson’s diaries revealed that he had travelled by train across Australia after leaving Perth, and had visited Adelaide, Melbourne, and Sydney, where he spent Christmas in 1920. He then went into the New South Wales heartland, north into Queensland, and then eventually to Tasmania in April 1921, after a sojourn in New Zealand. The diaries said little but did give the names of plants collected, with collection numbers. Yet, while I came across the odd specimen from Queensland and Tasmania, I found none collected by Wilson from New South Wales or Victoria. This was a mystery. At the end of each day in the herbarium, which closes precisely at five o’clock, I would close the compactors, pull down the bar, and turn off the light, as directed.

Wilson returned to the Arnold Arboretum in 1922, after visiting India and various Commonwealth countries in southern Africa, which were recorded in his images. But what had happened to the herbarium specimens and images from a major part of his Australian tour? One day, in the middle of my stay, I turned to materials in the archives, to see if I could shed some light on the mystery of the missing Australians. The key was in a box of newspaper reports. An article described Wilson’s “great disappointment” at losing much of the collection because the boat carrying two large consignments of photographic plates and specimens was lost at sea. The ever-helpful Lane-Poole had earlier shipped the entire Western Australian collection, which arrived safely in Boston. Sargent’s response is not known. He had considered a study of Tasmanian conifers “one of the most important objects of the expedition,”vi but those collections were all gone. Other questions were answered: printed black-and-white images from Tasmania were sent by the noted Hobart photographer John Beattie after the loss of Wilson’s collection, and unlabelled lantern slides, sent to Wilson, all depict New Zealand in a travelogue style.

One of the many delights of my own expedition into the 1920s expedition was the people I met along the way who still enliven the images and specimen sheets. Many of the herbarium specimens had been reassigned by David Moresby Moore, a British plant taxonomist and systematic botanist with a major interest in the flora of Gondwana, Patagonia, and the Antarctic and sub-Antarctic islands. His work amid the Australian collection at Harvard in the 1960s made my job far easier, because the plants were correctly assigned and thus correctly catalogued. “DM Moore”—his appellation on the bright white labels near Wilson’s originals—was a welcome sight.

Black-and-white photograph of plant
Kingia australis—slow-growing and long-lived monocots—fascinated Wilson. He called them “weird and extraordinary” and suggested, in Plant Hunting, that “the scene would be more complete if … a Nothotherium, a Dinosaurus, a Plesiosaurus or some other monster of the remote Lizard Age” were present. Arnold Arboretum Archives

Other collectors assisted the Arnold Arboretum and donated specimens from Western Australia, South Australia, and Queensland as part of the Expedition. Most important were those submitted by Frederick Schock (“F. M. C Schock” on the labels), who was a forest ranger in Western Australia. Schock’s specimens were largely collected in 1916, but they were sent to Harvard after Wilson returned and were labelled “Arnold Arboretum Expedition to Australasia, India, and Africa.” Many included flower parts that had not been seen by Wilson during his summer visit, because many of these species, typical of southern Australia, do not flower in summer.

With the addition of these donated specimens, one of the missions of the expedition began to become apparent to me: to add to the global collection of specimens and images held at the Arnold Arboretum. The Arnold Arboretum celebrated its fiftieth anniversary in 1922, and Charles Sprague Sargent, the founding director, laid out this global vision in a report on the Arboretum. “If the Arboretum is to become a great institution for gathering and spreading information about trees and allied plants, specimens and a series of photographs of every species of tree in the world should be found in the herbarium,” Sargent wrote. His ambition was that the work already achieved “should be extended over the rest of the world.”vii

Given Sargent’s desire to develop global collections of photographs and herbarium specimens, it made sense that additional Australian specimens would be requested from Schock and others, to fill gaps within Wilson’s collection. While the Arnold Arboretum could only grow plants that suited Boston’s cold winters and humid summers, Wilson’s expedition to Commonwealth countries revealed the equal importance of the herbarium and archives for institutional collecting goals. I had noted, in the herbarium, hundreds of specimens from Australia that were not from trees and that were of botanical interest, rather than of forestry value, reflecting Sargent’s desire for a comprehensive collection.

I was also struck by letters of thanks from Sargent regarding the donation of pamphlets and books on specific aspects of the world’s flora, as well as the contribution of physical specimens (including cones and seeds), sent from the countries visited on Wilson’s expedition, even though these would not grow in Boston. With these materials, the various missions of the expedition to Australia became even more apparent. In addition to collecting images and specimens, Wilson was to make connections between the Arboretum and the staff of other international botanical institutions, while investigating potential timber trees for production in the United States and assessing firsthand the state of forests in the world. Wilson achieved all these goals despite the loss of much of the physical collection.

Wilson’s travelling companions in Western Australia were highly informed and are now famous men in Australian botany. I wondered what they talked about, especially given Lane-Poole’s desperate unhappiness with the lack of forest protection in Australia, and Wilson’s diary comments about the ruthless destruction of woodlands for agriculture in Australia.viii Only a few months after Wilson’s visit, Lane-Poole resigned, in 1922, as the conservator of forests because the government did not appear interested in conservation but was solely concerned with timber extraction. Letters between Wilson and Sargent show that the whole idea of forest protection was of great importance to the expedition because they both saw that forests were under threat across the world. This suggested to me that the conservation movement was more alive in the 1920s than many of us fully appreciate today.

Black-and-white photograph of Wilson stranding in shaded grove
Wilson stands within a jarrah (Eucalyptus marginata) forest, in the Darling Scarp, east of Perth. The trees beside him have been scarred by fire. Arnold Arboretum Archives

Wilson, Sargent, and Lane-Poole all saw that the world’s forests were in danger of overexploitation and habitat loss, and both Wilson and Lane-Poole named the loss of large old trees as of greatest concern in Western Australia. Yet one hundred years later, botanists and conservationists are still raising this issue because it needs to be raised—surely something that would have saddened these men. The great banksia woodlands surrounding Perth have been substantially lost due to suburban development, and the woodlands east of the Darling Scarp, where Wilson noted an abundance of “curious,” “wondrous,” and “extraordinary” plants, continued to be clear-cut for agriculture into the 1980s. Today, ecological agriculture and ecosystem repair are imperatives for the future.

With my time at Harvard running out, I had to cease work at the herbarium and say my goodbyes at the Hunnewell Building and the Weld Hill laboratories, where I had my office. And I had found that the answers to my search for the Arnold Arboretum’s Expedition into Australia’s spectacular flora lay not simply in one place. As Sargent noted, the arboretum is a three-part collection, with a living museum, an herbarium, and a library.ix I had needed all of the resources and staff of the arboretum to begin to understand this last great journey that Wilson undertook.


Margaret Grose thanks the Arnold Arboretum for a Sargent Award for Visiting Scholars, Anthony Brach of the Harvard Herbaria, and Lisa Pearson, Jonathan Damery, Peter Del Tredici, and Ned Friedman of the Arnold Arboretum.

The map in this article was created using Esri, USGS, NGA, NASA, CGIAR, N Robinson, NCEAS, NLS, OS, NMA, Geodatastyrelsen, Rijkswaterstaat, GSA, Geoland, FEMA, Intermap and the GIS user community.


   i Wilson, E. H. 1985. Smoke that Thunders. London: Waterstone & Co. Limited. (Original work published as Wilson, E. H. 1927. Plant Hunting, Vol. 1. Boston: The Stratford Company.)

  ii Crisp, M. D. and Cook, L. G. 2013. How was the Australian flora assembled over the last 65 million years? A molecular and phylogenetic perspective. Annual Review of Ecology and Systematics, 44: 303–324.

iii See Wilson, 1985, above.

iv Wilson, E. H. 1920. Alternating diary and collection notes, October 22, 1920 (box 14, folder 3–4). Ernest Henry Wilson (1876–1930) papers, Arnold Arboretum Horticultural Library, Harvard University.

  v Ibid.

vi Sargent, C. S. 1921. Sargent to E. H. Wilson, April 18, 1921 (volume 9, page 599–600). Charles Sprague Sargent (1841–1927) papers, Arnold Arboretum Horticultural Library, Harvard University.

Citation: Grose, M. 2019. Searching for Wilson’s Expedition to Australia. Arnoldia, 76(4): 2–13.

vii Sargent, C. S. 1923. The first fifty years of the Arnold Arboretum. Journal of the Arnold Arboretum, 3(3): 127–171.

viii Wilson, E. H. 1920. Alternating diary and collection notes, October 25, 1920 (box 14, folder 3–4).

ix Sargent, C. S. 1925. The Arnold Arboretum. In Report of the President and the Treasurer of Harvard College, 1923–24 (pp. 229–232). Boston: Harvard University.

Margaret Grose is a senior lecturer in landscape architecture at the University of Melbourne, where her research and teaching merges design and ecological science. Margaret has published across science, landscape architecture, and planning.