Greetings Victor,
On the subject of stinging trees, I once observed a mature male
Satin Bowerbird in the Knoll National Park on Tamborine Mountain in
southern Queensland, browsing on the leaves of the Shining-leaved Stinging
Tree (Dendrocnide photinophylla). And more remarkably, I was called by a
Zoologist friend to witness a common ringtail possum dining happily on the
leaves of a Giant Stinging Tree (D. excelsa) a little south of Mt Mistake
in the Main Range National Park, also in southern Queensland.
(There are no further bird references in this account of stinging trees, in
case any birding-aus subscriber wishes to hit the delete button now.)
I grew up with three species of these stingers and know them well. As a
very small child (early 1930s) I quickly learnt to avoid the Giant Stinging
Tree and the Gympie - they have very large and distinctive leaves. The
Shining-leaved Stinging Tree occasionally caught me because its leaves are
quite undistinguished, and look much like many other rainforest trees.
However its stinging hairs are relatively sparse and so it is the least
painful of the three to brush against.
My worst 'stinger' experience was in a Hoop Pine plantation in the Mary
Valley south of Gympie in southern Queensland. I was selecting trees for
removal in a thinning experiment. Stems of the best form had been selected
previously and pruned to a height of six metres, and the objective was to
reduce the trees per acre to a particular number by removing those of poor
form that were over-topping the pruned stems. This meant that I had to
spend my time looking at the tops of the trees. I hadn't realised that
the plantation had a generous stocking of regrowth and seedling stingers,
both Gympie and Giant, and I was wearing shorts. It was inevitable that I
was stung repeatedly. However, after about two hours my legs went numb and
I felt no more pain. (I don't recommend it as a cure though.)
Juice of the stem of the Cunjevoi (Alocasia macrorrhizos), a plant of
similar appearance to an Arum Lily, but with green flowers, is the usual
bushman's remedy. Bernard O'Reilly, at Lamington National Park, he of the
Stinson Crash fame, swore by the juice of the inner bark of the stinging
tree itself - as recommended by one of your earlier respondents. The
commercial product 'Stingose' is effective, I'm told. (There used to be a
brand of anti-perspirant/deodorant with the same formulation and much
cheaper, but I don't know if it is still available with the right
formulation.)
W.D. Francis, then Queensland Government Botanist and author of "Australian
Rain-Forest Trees" delivered the C.T. White Memorial Lecture to the
Queensland Naturalists Club in 1955, with Australian Stinging Trees as his
subject. He had no faith in the Cunjevoi treatment: "I tried this widely
advocated rememdy very many years ago on the sting of (the Gympie)," he
wrote, "and it seemed to intensify the pain. Mr J. Waller of "Neusa Vale"
who has lived at Kin Kin all his life informs me that in his experience the
Cunjevoi has no effect in reducing the stinging sensation."
On vernacular names, Francis again quotes Mr Waller as saying that the name
"Gimpi Gimpi" was applied by the Aboriginal people to the Shining-leaved
Stinging Tree (Dendrocnide photinophylla) and the name of the town "Gympie"
was derived from this. However in popular parlance 'Gympie'is now applied
to the shrub or small tree, Dendrocnide moroides - perhaps because its
sting is the most painful.
The Australian Flora says of D. moroides: "Perhaps the most virulent
stinger in the genus ..." (There are 37 species of Dendrocnide native to
SE Asia, Australia and Pacific Islands. Australia has five species.)
Francis also regarded moroides as the most virulent and used it as the
basis of some experiments which demonstrated its virulence. In one he took
an Herbarium specimen collected (by C.T. White!) in 1909 (almost half a
century earlier) and rubbed the upper surface of a leaf on the left side of
his shin. This is his report of the effect:
"After a latent period of several minutes the stinging sensation commenced
and gained in intensity for about half an hour. The stinging sensation was
continuous throughout the day and night. No reddening of the skin was
observed. On the second day the sensation was felt slightly after washing
and drying. On the third day it was felt several times during the day and
was not felt on the fourth day."
And that specimen had been stored between sheets of absorbent paper for 46
years!
Francis put a fresh moroides leaf in an oven at something over 110 degrees
Celsius for 10 minutes, by which time the leaf blade had curled up and was
dark brown. The leaf stalk was greenish brown and had shrunk from 6 mm to
4 mm in diameter. He rubbed it on the skin of the forearm:
"Within a few seconds the intense stinging sensation was felt. The
skin immediately became red and broke out into small white lumps (?
sebaceous swellings) 1-2 mm in diameter and larger white lumps 4-6 mm in
diameter. Later the same day slight pain was felt at the elbow and in the
upper arm but no underarm pain was experienced. The stinging sensation
remained continuous and intense throughout the day. Twentyfour hours after
the beginning of the experiment the stinging sensation was still felt and
occasional twinges of pain were experienced. The stinging sensation was
still experienced after washing and drying three months after the
experiment was carried out. Three days after the beginning of the
experiment the white areas disappeared and the redness disappeared on the
fifth day."
(Note that Francis "rubbed the leaf on his skin". This would give a far
more severe sting than a casual brush against a leaf in the bush.)
Next Francis took a moroides leaf that had been dried between absorbent
paper for 3 weeks, boiled it for 20 mintutes and allowed it to dry in air.
He applied it to the right side of the shin. Pain after 15 seconds;
redness in 10 minutes but more conspicuous after one and a half hours.
Greatest stinging sensation was half to one hour after application.
Stinging sensation after washing and drying continued until seven days
after the initial application.
He also tried with a fresh young leaf of D. excelsa, boiled for 20 minutes
and allowed to dry. Stinging sensation after a few seconds, but no
reddening of the skin. On the second day slight stinging sensation after
washing and drying, but not thereafter.
Francis referred to a paper by J.M. Petrie (Proceedings of the Linnaean
Society of NSW, 31: 530-545, 1906) "The Stinging Property of the Giant
Nettle Tree". Petrie concluded that the stinging property of the hairs of
D. excelsa is due to free concentrated formic and acetic acid. He found
that the hairs are composed of silica. Francis could find no reference to
any investigation of the stinging properties of the other Dendrocnide
species. It seems safe to predict that they would be similar.
As to the physical characteristics of the stinging hairs, Francis writes:
"When one of the largest hairs of the three species is grasped by
forceps it breaks off at the base. Upon contact with an object the hollow
heads at the apex are also broken off. In the case of the smaller hairs
because of the fineness and brittleness of the portion near the apex the
point is broken off when contact with a resistant substance is made. In
each instance the apical portion of the hairs is left with a fine, jagged,
often oblique, hollow point which allows the contents of the hairs to
emerge. These observations explain how the hairs on contact or pressure
are forced into the skin and become detatched from the plant. The hairs of
all types can be compared with hollow needles. The larger hairs are in
reality giant cells."
So there you have it. Brush against one of these leaves and you have in
effect a number of micro-hypodermic syringes left sticking in your skin.
My old Botany Professor (University of Queensland) Dr D.A. Herbert,
recommended shaving the affected area. This removes any protruding
stinging hairs and so stops any further drainage of acid into your skin.
In case you are interested in species distribution:
Dendrocnide corallodesme occurs in the Iron Range and McIlwraith Range
areas of Cape York Peninsula, and New Guinea. Stinging hairs are mainly on
the midrib of the leaf and on the flowers in this species.
D.moroides occurs in eastern Queensland and NSW; also the Moluccas and
Indonesia. Shrub or small tree to a maximum height of 10 metres (Aust.
Flora).
D. cordata. C.York Peninsula; the Moluccas, New Guinea and the Bismark
Archipelago. Shrub or tree to 10 metres high.
D. photinophylla, Cape York to the Nepean region of NSW. Tree to 25 metres.
D. excelsa from Bunya Mtns to Kiama, NSW. Grows to a height of 35 metres
according to the Australian Flora, and in Rain-Forest Trees , Francis says
to a stem diameter of 6 feet (about 2 metres). I reckon I know for a
larger and taller one in Palm Grove National Park on Tamborine Mountain,
but measuring total height of a standing tree in the rainforest is very
difficult.
I've probably given you more than you wanted, and perhaps irritated a few
birding-aus people in the process, but it's an interesting subject, and
anyone observing birds within the habitat of these trees should make sure
they can identify and avoid them.
And how did this ferocious defence mechanism evolve when a caterpillar (as
you pointed out), a bird and a possum, all can eat the leaves with
impunity? I leave you - and any other reader who has persisted this far -
to consider that conundrum.
Cheers
Syd Curtis at Hawthorne, Queensland.
H Syd Curtis
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