Fleur de tan

J.A. Smith wrote in 1878:

Mr. Colenso related the first use of the barks of New Zealand trees for tanning purposes, which took place at Ngunguru (between Whangarei and the Bay of Islands), in the years 1839, 1840, and 1841, which had come under his special notice while living at the Bay of Islands, and often travelling in that district. This was the first place in New Zealand where hides were tanned for leather, the whole process was particularly primitive. Extracts of those several barks there used, with specimens of the trees producing them, he had sent to Sir W. J. Hooker, the Director of the Royal Gardens at Kew, long before New Zealand became a British Colony.

The words tannin, tanning and tan are all derived from the Medieval Latin word tannare which means to convert into leather. There are many processes for tanning leather and one is to use the tannins extracted from tree bark as the tanning agent. The bark of certain tree species, those rich in tannin, would be stockpiled for use. This created an excellent habitat for the slime mould, Fuligo septica, to feed and fruit. So when the French botanist Jean Marchant described it scientifically in 1727 he referred to it as “fleur de tan”. Which literally translates as bark flower but has become flowers of tan.

While the stockpiling of bark for tanning has never been prevalent in New Zealand (see footnote) the use of bark, particularly pine bark, and wood chips as garden mulch has become widespread in the last 30 years. This has provided a great habitat for Fuligo septica. I followed the development of a fruit body of the bark flower over 4 days in my front garden.

The slime mould congregates overnight into a single bright yellow mass that begins to develop into a fruiting body.

Fuligo septica ‎6.27am 2 ‎Feb ‎2018 [photo Geoff Ridley]

By mid-afternoon it has started turning brown.

Fuligo septica 4:36pm 2 ‎Feb ‎2018 [photo Geoff Ridley]

By the next day it is beginning to dry out.

Fuligo septica 7.17am 3 ‎Feb ‎2018 [photo Geoff Ridley]

Fuligo septica 10.15am 4 ‎Feb ‎2018 [photo Geoff Ridley]

On day 4 the content of the fruiting body has been converted to a dry mass of brown spores and the outer layer has fragmented and is flaking. The dry spores are now exposed and ready to blow away in the wind.

Fuligo septica 9.40am 6 ‎Feb ‎2018 [photo Geoff Ridley]


Smith JA 1878. On certain New Zealand and Australian Barks useful for Tanning Purposes. Transactions and Proceedings of the Royal Society of New Zealand 11: 570-571

Footnote: The of a bark-based tanning industry is another fungal story to be told later.


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