It stands to reason: the fluff appears in the air and we start sneezing.
Some Canberrans have been heard moaning about the little white balls that float like snow. They see the fluff and their eyes start watering.
Ergo, as they say in the posher parts of the city, the fluff must cause the sneezing.
Not so, according to the city's scientists. Two and two don't make five.
It's all about causality. Just because spending on credit cards goes up before Christmas doesn't mean credit card spending causes Christmas.
And just as fluff appears and then sneezing starts doesn't mean fluff causes sneezing.
"The fluff itself is in many people's minds linked to allergic reactions such as hay fever or asthma, but it is unlikely to be a direct trigger," said Professor Simon Haberle, director of the ANU's School of Culture, History and Language.
See it for what it is - plants celebrating spring. Enjoy it.ANU guide to the Canberra fluff
The botanists at the ANU's Fenner School published an information guide. "We love blaming the first thing we see," it says.
"Statistics students on campus beware - the connection between fluff and hay fever is an illusory correlation (there is no real connection) or detection bias (fluff is easy to see, so easy to blame).
"The reality is that the production of fluff coincides with springtime pollen production."
But the ANU botany boffins do like the stuff: "See it for what it is - plants celebrating spring. Enjoy it."
Apart from anything else, the unpopular fluff from the poplar tree (geddit?) is not allergenic pollen (the pollen which prompts allergic reactions like sneezing watering eyes and wheezing).
It is a seed encased in the flower of the poplar tree - the lighter-than-air fluff (ingeniously) floats the seed far and wide.
It's too big to be inhaled, according to Professor Haberle. Allergenic pollen is minute enough to be breathable at between 10 and 100 microns (a human hair is about 75 to 100 microns thick - blond is finer than dark hair).
Professor Haberle dismisses another misconception connected to the appearance of fluff at this time of year. It is said that students who haven't started serious study when the fluff appears will go down in flames when they face the exam paper.
"There's no evidence for that," he said. Though he does think it might cause a bit of anxiety so the false belief might be useful in prompting students to buck up.
The sighting of fluff is more of a ritual for this city - a bit of a talking point.
Lots of places have their seasonal rituals.
In the United States, it's just not OK to wear white shoes after Labor Day. Or white suits - very tacky. Taste note: some believe that white shoes should never be worn.
In Britain, the saying is: "Ne'er cast a clout 'til May is out" - Never cast off your outer clothes until May is over (or until the mayflower is in bloom).
A call for other common Canberra sayings produced these: "You shouldn't plant tomatoes until Melbourne Cup day" and "You shouldn't turn on the heater until Anzac Day."
The ANU scientists, by the way, have their own unromantic way of describing the beauty of the willows and aspens that generate the fluff?
"One of my favourite sylvan images is the shimmering light cast by millions of quaking aspen (Populus tremuloides) leaves as a light breeze pushes the flattened petioles (a kind of stalk) to and fro on an autumnal afternoon. The diverse experience that a diverse tapestry of trees deliver is a good thing," one said, perhaps unpoetically.