1885: the paper that named mycorrhiza

A ministry, and a question about truffles

The paper begins as a piece of official business. The Prussian Minister for Agriculture, Domains and Forests had asked Albert Bernhard Frank (1839–1900) to establish, by scientific investigation, what governs the occurrence and development of truffles, so that they might be cultivated in the Kingdom of Prussia. The text is signed from the Plant Physiology Institute of the Royal Agricultural College in Berlin, where Frank then worked. Three observations set his direction: that true truffles are always found near living trees; that in the Prussian truffle districts the trees in question were beech, hornbeam and oak; and that Reess had described a connection, reminiscent of parasitism, between the mycelium of Elaphomyces and pine roots. Did truffle mycelium, then, also attach itself to a living root?

What came back was larger than the question. The paper runs from page 128 to page 145 of Heft 4, volume 3 of the Berichte der Deutschen Botanischen Gesellschaft, and carries the number 21. That numbering runs continuously through the whole year rather than restarting each Heft, so within Heft 4 it is the fourth communication of five. Beneath the title stands “Mit Tafel X” — with Plate X — and beneath that the date it arrived: 17 April 1885. The Heft opens on page 117 with a record headed “Sitzung vom 24. April 1885”, and the printed part is dated May 1885.

Those dates are worth keeping apart, because they collapse easily into a single scene. What the record proves is that Frank’s paper belongs to the Heft opened by the account of the session of 24 April. It does not prove that he stood up that day and read it out: the text had arrived a week earlier, and no source consulted here places him in the room. The pattern holds across the volume, whose ten parts each open with a session record, from 30 January on page 1 to 29 December on page 373, with nothing in August or September.

The word was offered with a “perhaps”

The sentence that coined the term is far more tentative than its later career suggests. The whole body, Frank writes, is neither tree root nor fungus alone but, like the thallus of a lichen, a union of two different beings into a single morphological organ — one that “may perhaps aptly be designated fungus-root, Mycorhiza”. The German is “vielleicht passend”. The name a discipline was built on entered the literature as a suggestion.

One small point deserves correcting wherever it is repeated. Frank did not write “mycorrhiza”. Deriving the term from the Greek μυκοριζα, he transliterated it with a single “r”, and the volume follows him: Woronin in Heft 6, Penzig in Heft 8, and Frank’s own further papers of 1887 and 1888. “Symbiosis” was not his coinage either. It is already in his title, inside the compound “Wurzelsymbiose”.

The scope, too, was narrower than the modern word implies. Frank used the long-abandoned family name “Cupuliferae” and lists oak, beech, hornbeam, hazel and sweet chestnut. Plate X bears that out. Its first figure shows, at natural size, a length of hornbeam root (Carpinus betulus) clothed in fungus-roots “mostly thickened in the manner of coral”; figure 3 gives the smooth sheath in surface view at 145 times magnification; figure 4 the tip of a beech mycorrhiza (Fagus sylvatica) where the sheath frays into threads growing out into the soil; figure 5 a longitudinal section at 480 times. This is a paper about trees and about what is now called ectomycorrhiza. It is not about arbuscular mycorrhiza, and not about land plants in general.

Who had seen it first

Two parts later the same volume prints an objection. On 21 June 1885 Mikhail Woronin submitted a note titled, bluntly, “Ueber die Pilzwurzel (Mycorhiza) von B. Frank”. He had known the structure for two years, he says: in the summer of 1883, in Finland, he had been studying the structure and development of several fungi of the genus Boletus, among them Boletus edulis and Boletus scaber, and had come upon roots wrapped in a dense mycelium so like Frank’s drawings that they might almost have served as the models for them. He suspected the boletes were the partners, but is candid that only an experiment could settle it: either raise a fruit body from the mycorrhiza, or sow spores onto a root and obtain one. He had not set those cultures up.

His real complaint was about interpretation. Woronin had taken the sheathing of roots for a particular kind of parasitism; Frank read it as symbiosis and set it beside the lichens. Woronin does not argue against that reading. He argues that it is not new, having been stated clearly three years earlier by Franciszek Kamieński (1851–1912), whose 1882 paper “Les organes végétatifs du Monotropa Hypopitys L.”, in volume 24 of the Cherbourg society’s memoirs, described the arrangement not only for yellow bird’s-nest (Monotropa hypopitys) but for beech and the conifers, with a figure for beech. All rights of priority in the matter, the note concludes, belong not to Herr B. Frank but to Herr Fr. Kamieński.

Frank replied before the year was out, in a communication submitted on 8 September 1885. He opens with thanks: the Berlin libraries did not yet hold the Cherbourg volume, so Kamieński himself had posted him a copy — after which Frank set about showing that Woronin was wrong. Kamieński, he argued, confined mutual nutrition to the chlorophyll-less bird’s-nest and placed fungus-sheathed tree roots in sharp contrast to it. This entry does not settle that quarrel. It records that the quarrel was live, in print, in the year the name was given.

What the date does not settle

Frank did not discover that roots and fungi live together, and did not say he had; his own paper reports at length on the sometimes very exact anatomical observations of earlier researchers. What was new was the name and the physiological reading — that the fungus performs, in his phrase, nurse’s services for the tree and takes over its entire uptake of food from the soil.

Nor did he demonstrate that transfer. James M. Trappe, who translated the paper into English, summarises the hypotheses in a separate commentary: that what we now call ectomycorrhizae were widespread on the root systems of many woody species across a great diversity of habitats and soils; that the fungus draws nutrients from both mineral soil and humus and passes them to the tree; and that the tree in turn feeds the fungus. He is blunt about the reception. Much of the scientific community opposed those hypotheses at first, and although nearly all of them have since been unequivocally demonstrated, many decades were needed to reach conclusive evidence. On his 2005 assessment the shift in thinking Frank set off was still being absorbed, 120 years and tens of thousands of scientific papers after the term was coined.

The translation itself calls for care. The sentences quoted above are from the German of 1885; the English version appeared online on 10 November 2004 and in the June 2005 issue of Mycorrhiza, and Trappe’s note states that it is not a literal translation, because nineteenth-century German scientific style does not sit comfortably in twenty-first-century English. It also revises an earlier translation from the proceedings of the sixth North American conference on mycorrhizae in 1985, and the publisher’s page shows the metadata and that note alone, the full text being behind a paywall.

The volume, and the root

The 1885 volume is scanned and open, so none of this needs a subscription to check: the session record on page 117, Frank’s paper on pages 128 to 145, the explanation of Plate X on page 144, Woronin’s note on pages 205 and 206. It is the twenty-first-century translation that costs money, not the nineteenth-century original.

The field version is just as available. An exposed root tip of hornbeam or beech — thickened, forked, wrapped in a pale fungal sheath — is exactly the organ Frank showed at natural size in the first figure of Plate X, and exactly the one he named in 1885. A mushroom fruiting beside it may belong to the same partnership, but which fungus is paired with which tree cannot be settled by eye. Woronin ran up against that in 1883, and had the honesty to say so in print two years later.